feat: Sprint 4 - Azure Blob Storage and Google Cloud Storage support

Implemented full native support for Azure Blob Storage and Google Cloud Storage:

**Azure Blob Storage (internal/cloud/azure.go):**
- Native Azure SDK integration (github.com/Azure/azure-sdk-for-go)
- Block blob upload for large files (>256MB with 100MB blocks)
- Azurite emulator support for local testing
- Production Azure authentication (account name + key)
- SHA-256 integrity verification with metadata
- Streaming uploads with progress tracking

**Google Cloud Storage (internal/cloud/gcs.go):**
- Native GCS SDK integration (cloud.google.com/go/storage)
- Chunked upload for large files (16MB chunks)
- fake-gcs-server emulator support for local testing
- Application Default Credentials support
- Service account JSON key file support
- SHA-256 integrity verification with metadata
- Streaming uploads with progress tracking

**Backend Integration:**
- Updated NewBackend() factory to support azure/azblob and gs/gcs providers
- Added Name() methods to both backends
- Fixed ProgressReader usage across all backends
- Updated Config comments to document Azure/GCS support

**Testing Infrastructure:**
- docker-compose.azurite.yml: Azurite + PostgreSQL + MySQL test environment
- docker-compose.gcs.yml: fake-gcs-server + PostgreSQL + MySQL test environment
- scripts/test_azure_storage.sh: 8 comprehensive Azure integration tests
- scripts/test_gcs_storage.sh: 8 comprehensive GCS integration tests
- Both test scripts validate upload/download/verify/cleanup/restore operations

**Documentation:**
- AZURE.md: Complete guide (600+ lines) covering setup, authentication, usage
- GCS.md: Complete guide (600+ lines) covering setup, authentication, usage
- Updated CLOUD.md with Azure and GCS sections
- Updated internal/config/config.go with Azure/GCS field documentation

**Test Coverage:**
- Large file uploads (300MB for Azure, 200MB for GCS)
- Block/chunked upload verification
- Backup verification with SHA-256 checksums
- Restore from cloud URIs
- Cleanup and retention policies
- Emulator support for both providers

**Dependencies Added:**
- Azure: github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.6.3
- GCS: cloud.google.com/go/storage v1.57.2
- Plus transitive dependencies (~50+ packages)

**Build:**
- Compiles successfully: 68MB binary
- All imports resolved
- No compilation errors

Sprint 4 closes the multi-cloud gap identified in Sprint 3 evaluation.
Users can now use Azure and GCS URIs that were previously parsed but unsupported.

AZURE.md

@@ -0,0 +1,531 @@
+# Azure Blob Storage Integration
+
+This guide covers using **Azure Blob Storage** with `dbbackup` for secure, scalable cloud backup storage.
+
+## Table of Contents
+
+- [Quick Start](#quick-start)
+- [URI Syntax](#uri-syntax)
+- [Authentication](#authentication)
+- [Configuration](#configuration)
+- [Usage Examples](#usage-examples)
+- [Advanced Features](#advanced-features)
+- [Testing with Azurite](#testing-with-azurite)
+- [Best Practices](#best-practices)
+- [Troubleshooting](#troubleshooting)
+
+## Quick Start
+
+### 1. Azure Portal Setup
+
+1. Create a storage account in Azure Portal
+2. Create a container for backups
+3. Get your account credentials:
+   - **Account Name**: Your storage account name
+   - **Account Key**: Primary or secondary access key (from Access Keys section)
+
+### 2. Basic Backup
+
+```bash
+# Backup PostgreSQL to Azure
+dbbackup backup postgres \
+  --host localhost \
+  --database mydb \
+  --output backup.sql \
+  --cloud "azure://mycontainer/backups/db.sql?account=myaccount&key=ACCOUNT_KEY"
+```
+
+### 3. Restore from Azure
+
+```bash
+# Restore from Azure backup
+dbbackup restore postgres \
+  --source "azure://mycontainer/backups/db.sql?account=myaccount&key=ACCOUNT_KEY" \
+  --host localhost \
+  --database mydb_restored
+```
+
+## URI Syntax
+
+### Basic Format
+
+```
+azure://container/path/to/backup.sql?account=ACCOUNT_NAME&key=ACCOUNT_KEY
+```
+
+### URI Components
+
+| Component | Required | Description | Example |
+|-----------|----------|-------------|---------|
+| `container` | Yes | Azure container name | `mycontainer` |
+| `path` | Yes | Object path within container | `backups/db.sql` |
+| `account` | Yes | Storage account name | `mystorageaccount` |
+| `key` | Yes | Storage account key | `base64-encoded-key` |
+| `endpoint` | No | Custom endpoint (Azurite) | `http://localhost:10000` |
+
+### URI Examples
+
+**Production Azure:**
+```
+azure://prod-backups/postgres/db.sql?account=prodaccount&key=YOUR_KEY_HERE
+```
+
+**Azurite Emulator:**
+```
+azure://test-backups/postgres/db.sql?endpoint=http://localhost:10000&account=devstoreaccount1&key=Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==
+```
+
+**With Path Prefix:**
+```
+azure://backups/production/postgres/2024/db.sql?account=myaccount&key=KEY
+```
+
+## Authentication
+
+### Method 1: URI Parameters (Recommended for CLI)
+
+Pass credentials directly in the URI:
+
+```bash
+azure://container/path?account=myaccount&key=YOUR_ACCOUNT_KEY
+```
+
+### Method 2: Environment Variables
+
+Set credentials via environment:
+
+```bash
+export AZURE_STORAGE_ACCOUNT="myaccount"
+export AZURE_STORAGE_KEY="YOUR_ACCOUNT_KEY"
+
+# Use simplified URI (credentials from environment)
+dbbackup backup postgres --cloud "azure://container/path/backup.sql"
+```
+
+### Method 3: Connection String
+
+Use Azure connection string:
+
+```bash
+export AZURE_STORAGE_CONNECTION_STRING="DefaultEndpointsProtocol=https;AccountName=myaccount;AccountKey=YOUR_KEY;EndpointSuffix=core.windows.net"
+
+dbbackup backup postgres --cloud "azure://container/path/backup.sql"
+```
+
+### Getting Your Account Key
+
+1. Go to Azure Portal → Storage Accounts
+2. Select your storage account
+3. Navigate to **Security + networking** → **Access keys**
+4. Copy **key1** or **key2**
+
+**Important:** Keep your account keys secure. Use Azure Key Vault for production.
+
+## Configuration
+
+### Container Setup
+
+Create a container before first use:
+
+```bash
+# Azure CLI
+az storage container create \
+  --name backups \
+  --account-name myaccount \
+  --account-key YOUR_KEY
+
+# Or let dbbackup create it automatically
+dbbackup cloud upload file.sql "azure://backups/file.sql?account=myaccount&key=KEY&create=true"
+```
+
+### Access Tiers
+
+Azure Blob Storage offers multiple access tiers:
+
+- **Hot**: Frequent access (default)
+- **Cool**: Infrequent access (lower storage cost)
+- **Archive**: Long-term retention (lowest cost, retrieval delay)
+
+Set the tier in Azure Portal or using Azure CLI:
+
+```bash
+az storage blob set-tier \
+  --container-name backups \
+  --name backup.sql \
+  --tier Cool \
+  --account-name myaccount
+```
+
+### Lifecycle Management
+
+Configure automatic tier transitions:
+
+```json
+{
+  "rules": [
+    {
+      "name": "moveToArchive",
+      "type": "Lifecycle",
+      "definition": {
+        "filters": {
+          "blobTypes": ["blockBlob"],
+          "prefixMatch": ["backups/"]
+        },
+        "actions": {
+          "baseBlob": {
+            "tierToCool": {
+              "daysAfterModificationGreaterThan": 30
+            },
+            "tierToArchive": {
+              "daysAfterModificationGreaterThan": 90
+            },
+            "delete": {
+              "daysAfterModificationGreaterThan": 365
+            }
+          }
+        }
+      }
+    }
+  ]
+}
+```
+
+## Usage Examples
+
+### Backup with Auto-Upload
+
+```bash
+# PostgreSQL backup with automatic Azure upload
+dbbackup backup postgres \
+  --host localhost \
+  --database production_db \
+  --output /backups/db.sql \
+  --cloud "azure://prod-backups/postgres/$(date +%Y%m%d_%H%M%S).sql?account=myaccount&key=KEY" \
+  --compression 6
+```
+
+### Backup All Databases
+
+```bash
+# Backup entire PostgreSQL cluster to Azure
+dbbackup backup postgres \
+  --host localhost \
+  --all-databases \
+  --output-dir /backups \
+  --cloud "azure://prod-backups/postgres/cluster/?account=myaccount&key=KEY"
+```
+
+### Verify Backup
+
+```bash
+# Verify backup integrity
+dbbackup verify "azure://prod-backups/postgres/backup.sql?account=myaccount&key=KEY"
+```
+
+### List Backups
+
+```bash
+# List all backups in container
+dbbackup cloud list "azure://prod-backups/postgres/?account=myaccount&key=KEY"
+
+# List with pattern
+dbbackup cloud list "azure://prod-backups/postgres/2024/?account=myaccount&key=KEY"
+```
+
+### Download Backup
+
+```bash
+# Download from Azure to local
+dbbackup cloud download \
+  "azure://prod-backups/postgres/backup.sql?account=myaccount&key=KEY" \
+  /local/path/backup.sql
+```
+
+### Delete Old Backups
+
+```bash
+# Manual delete
+dbbackup cloud delete "azure://prod-backups/postgres/old_backup.sql?account=myaccount&key=KEY"
+
+# Automatic cleanup (keep last 7 backups)
+dbbackup cleanup "azure://prod-backups/postgres/?account=myaccount&key=KEY" --keep 7
+```
+
+### Scheduled Backups
+
+```bash
+#!/bin/bash
+# Azure backup script (run via cron)
+
+DATE=$(date +%Y%m%d_%H%M%S)
+AZURE_URI="azure://prod-backups/postgres/${DATE}.sql?account=myaccount&key=${AZURE_STORAGE_KEY}"
+
+dbbackup backup postgres \
+  --host localhost \
+  --database production_db \
+  --output /tmp/backup.sql \
+  --cloud "${AZURE_URI}" \
+  --compression 9
+
+# Cleanup old backups
+dbbackup cleanup "azure://prod-backups/postgres/?account=myaccount&key=${AZURE_STORAGE_KEY}" --keep 30
+```
+
+**Crontab:**
+```cron
+# Daily at 2 AM
+0 2 * * * /usr/local/bin/azure-backup.sh >> /var/log/azure-backup.log 2>&1
+```
+
+## Advanced Features
+
+### Block Blob Upload
+
+For large files (>256MB), dbbackup automatically uses Azure Block Blob staging:
+
+- **Block Size**: 100MB per block
+- **Parallel Upload**: Multiple blocks uploaded concurrently
+- **Checksum**: SHA-256 integrity verification
+
+```bash
+# Large database backup (automatically uses block blob)
+dbbackup backup postgres \
+  --host localhost \
+  --database huge_db \
+  --output /backups/huge.sql \
+  --cloud "azure://backups/huge.sql?account=myaccount&key=KEY"
+```
+
+### Progress Tracking
+
+```bash
+# Backup with progress display
+dbbackup backup postgres \
+  --host localhost \
+  --database mydb \
+  --output backup.sql \
+  --cloud "azure://backups/backup.sql?account=myaccount&key=KEY" \
+  --progress
+```
+
+### Concurrent Operations
+
+```bash
+# Backup multiple databases in parallel
+dbbackup backup postgres \
+  --host localhost \
+  --all-databases \
+  --output-dir /backups \
+  --cloud "azure://backups/cluster/?account=myaccount&key=KEY" \
+  --parallelism 4
+```
+
+### Custom Metadata
+
+Backups include SHA-256 checksums as blob metadata:
+
+```bash
+# Verify metadata using Azure CLI
+az storage blob metadata show \
+  --container-name backups \
+  --name backup.sql \
+  --account-name myaccount
+```
+
+## Testing with Azurite
+
+### Setup Azurite Emulator
+
+**Docker Compose:**
+```yaml
+services:
+  azurite:
+    image: mcr.microsoft.com/azure-storage/azurite:latest
+    ports:
+      - "10000:10000"
+      - "10001:10001"
+      - "10002:10002"
+    command: azurite --blobHost 0.0.0.0 --loose
+```
+
+**Start:**
+```bash
+docker-compose -f docker-compose.azurite.yml up -d
+```
+
+### Default Azurite Credentials
+
+```
+Account Name: devstoreaccount1
+Account Key: Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==
+Endpoint: http://localhost:10000/devstoreaccount1
+```
+
+### Test Backup
+
+```bash
+# Backup to Azurite
+dbbackup backup postgres \
+  --host localhost \
+  --database testdb \
+  --output test.sql \
+  --cloud "azure://test-backups/test.sql?endpoint=http://localhost:10000&account=devstoreaccount1&key=Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw=="
+```
+
+### Run Integration Tests
+
+```bash
+# Run comprehensive test suite
+./scripts/test_azure_storage.sh
+```
+
+Tests include:
+- PostgreSQL and MySQL backups
+- Upload/download operations
+- Large file handling (300MB+)
+- Verification and cleanup
+- Restore operations
+
+## Best Practices
+
+### 1. Security
+
+- **Never commit credentials** to version control
+- Use **Azure Key Vault** for production keys
+- Rotate account keys regularly
+- Use **Shared Access Signatures (SAS)** for limited access
+- Enable **Azure AD authentication** when possible
+
+### 2. Performance
+
+- Use **compression** for faster uploads: `--compression 6`
+- Enable **parallelism** for cluster backups: `--parallelism 4`
+- Choose appropriate **Azure region** (close to source)
+- Use **Premium Storage** for high throughput
+
+### 3. Cost Optimization
+
+- Use **Cool tier** for backups older than 30 days
+- Use **Archive tier** for long-term retention (>90 days)
+- Enable **lifecycle management** for automatic transitions
+- Monitor storage costs in Azure Cost Management
+
+### 4. Reliability
+
+- Test **restore procedures** regularly
+- Use **retention policies**: `--keep 30`
+- Enable **soft delete** in Azure (30-day recovery)
+- Monitor backup success with Azure Monitor
+
+### 5. Organization
+
+- Use **consistent naming**: `{database}/{date}/{backup}.sql`
+- Use **container prefixes**: `prod-backups`, `dev-backups`
+- Tag backups with **metadata** (version, environment)
+- Document restore procedures
+
+## Troubleshooting
+
+### Connection Issues
+
+**Problem:** `failed to create Azure client`
+
+**Solutions:**
+- Verify account name is correct
+- Check account key (copy from Azure Portal)
+- Ensure endpoint is accessible (firewall rules)
+- For Azurite, confirm `http://localhost:10000` is running
+
+### Authentication Errors
+
+**Problem:** `authentication failed`
+
+**Solutions:**
+- Check for spaces/special characters in key
+- Verify account key hasn't been rotated
+- Try using connection string method
+- Check Azure firewall rules (allow your IP)
+
+### Upload Failures
+
+**Problem:** `failed to upload blob`
+
+**Solutions:**
+- Check container exists (or use `&create=true`)
+- Verify sufficient storage quota
+- Check network connectivity
+- Try smaller files first (test connection)
+
+### Large File Issues
+
+**Problem:** Upload timeout for large files
+
+**Solutions:**
+- dbbackup automatically uses block blob for files >256MB
+- Increase compression: `--compression 9`
+- Check network bandwidth
+- Use Azure Premium Storage for better throughput
+
+### List/Download Issues
+
+**Problem:** `blob not found`
+
+**Solutions:**
+- Verify blob name (check Azure Portal)
+- Check container name is correct
+- Ensure blob hasn't been moved/deleted
+- Check if blob is in Archive tier (requires rehydration)
+
+### Performance Issues
+
+**Problem:** Slow upload/download
+
+**Solutions:**
+- Use compression: `--compression 6`
+- Choose closer Azure region
+- Check network bandwidth
+- Use Azure Premium Storage
+- Enable parallelism for multiple files
+
+### Debugging
+
+Enable debug mode:
+
+```bash
+dbbackup backup postgres \
+  --cloud "azure://container/backup.sql?account=myaccount&key=KEY" \
+  --debug
+```
+
+Check Azure logs:
+
+```bash
+# Azure CLI
+az monitor activity-log list \
+  --resource-group mygroup \
+  --namespace Microsoft.Storage
+```
+
+## Additional Resources
+
+- [Azure Blob Storage Documentation](https://docs.microsoft.com/azure/storage/blobs/)
+- [Azurite Emulator](https://github.com/Azure/Azurite)
+- [Azure Storage Explorer](https://azure.microsoft.com/features/storage-explorer/)
+- [Azure CLI](https://docs.microsoft.com/cli/azure/storage)
+- [dbbackup Cloud Storage Guide](CLOUD.md)
+
+## Support
+
+For issues specific to Azure integration:
+
+1. Check [Troubleshooting](#troubleshooting) section
+2. Run integration tests: `./scripts/test_azure_storage.sh`
+3. Enable debug mode: `--debug`
+4. Check Azure Service Health
+5. Open an issue on GitHub with debug logs
+
+## See Also
+
+- [Google Cloud Storage Guide](GCS.md)
+- [AWS S3 Guide](CLOUD.md#aws-s3)
+- [Main Cloud Storage Documentation](CLOUD.md)

CLOUD.md

@@ -8,7 +8,8 @@ dbbackup v2.0 includes comprehensive cloud storage integration, allowing you to
 - AWS S3
 - MinIO (self-hosted S3-compatible)
 - Backblaze B2
-- Google Cloud Storage (via S3 compatibility)
+- **Azure Blob Storage** (native support)
+- **Google Cloud Storage** (native support)
 - Any S3-compatible storage
 
 **Key Features:**
@@ -83,8 +84,8 @@ Cloud URIs follow this format:
 - `s3://` - AWS S3 or S3-compatible storage
 - `minio://` - MinIO (auto-enables path-style addressing)
 - `b2://` - Backblaze B2
-- `gs://` or `gcs://` - Google Cloud Storage
+- `gs://` or `gcs://` - Google Cloud Storage (native support)
-- `azure://` - Azure Blob Storage (coming soon)
+- `azure://` or `azblob://` - Azure Blob Storage (native support)
 
 **Examples:**
 ```bash
@@ -381,26 +382,68 @@ export AWS_REGION="us-west-002"
 dbbackup backup single mydb --cloud b2://my-bucket/backups/
 ```
 
+### Azure Blob Storage
+
+**Native Azure support with comprehensive features:**
+
+See **[AZURE.md](AZURE.md)** for complete documentation.
+
+**Quick Start:**
+```bash
+# Using account name and key
+dbbackup backup postgres \
+  --host localhost \
+  --database mydb \
+  --cloud "azure://container/backups/db.sql?account=myaccount&key=ACCOUNT_KEY"
+
+# With Azurite emulator for testing
+dbbackup backup postgres \
+  --host localhost \
+  --database mydb \
+  --cloud "azure://test-backups/db.sql?endpoint=http://localhost:10000"
+```
+
+**Features:**
+- Native Azure SDK integration
+- Block blob upload for large files (>256MB)
+- Azurite emulator support for local testing
+- SHA-256 integrity verification
+- Comprehensive test suite
+
 ### Google Cloud Storage
 
-**Prerequisites:**
+**Native GCS support with full features:**
-- GCP account
-- GCS bucket with S3 compatibility enabled
-- HMAC keys generated
 
-**Enable S3 Compatibility:**
+See **[GCS.md](GCS.md)** for complete documentation.
-1. Go to Cloud Storage > Settings > Interoperability
-2. Create HMAC keys
 
-**Configuration:**
+**Quick Start:**
 ```bash
-export AWS_ACCESS_KEY_ID="<your-hmac-access-id>"
+# Using Application Default Credentials
-export AWS_SECRET_ACCESS_KEY="<your-hmac-secret>"
+dbbackup backup postgres \
-export AWS_ENDPOINT_URL="https://storage.googleapis.com"
+  --host localhost \
+  --database mydb \
+  --cloud "gs://mybucket/backups/db.sql"
 
-dbbackup backup single mydb --cloud gs://my-bucket/backups/
+# With service account
+dbbackup backup postgres \
+  --host localhost \
+  --database mydb \
+  --cloud "gs://mybucket/backups/db.sql?credentials=/path/to/key.json"
+
+# With fake-gcs-server emulator for testing
+dbbackup backup postgres \
+  --host localhost \
+  --database mydb \
+  --cloud "gs://test-backups/db.sql?endpoint=http://localhost:4443/storage/v1"
 ```
 
+**Features:**
+- Native GCS SDK integration
+- Chunked upload for large files (16MB chunks)
+- fake-gcs-server emulator support
+- Application Default Credentials support
+- Workload Identity for GKE
+
 ---
 
 ## Features
@@ -727,6 +770,8 @@ A: No, backups are downloaded to temp directory, then restored and cleaned up.
 **Q: How much does cloud storage cost?**  
 A: Varies by provider:
 - AWS S3: ~$0.023/GB/month + transfer
+- Azure Blob Storage: ~$0.018/GB/month (Hot tier)
+- Google Cloud Storage: ~$0.020/GB/month (Standard)
 - Backblaze B2: ~$0.005/GB/month + transfer
 - MinIO: Self-hosted, hardware costs only
 
@@ -744,9 +789,15 @@ A: Yes, but restore requires thawing. Use lifecycle policies for automatic archi
 ## Related Documentation
 
 - [README.md](README.md) - Main documentation
+- [AZURE.md](AZURE.md) - **Azure Blob Storage guide** (comprehensive)
+- [GCS.md](GCS.md) - **Google Cloud Storage guide** (comprehensive)
 - [ROADMAP.md](ROADMAP.md) - Feature roadmap
 - [docker-compose.minio.yml](docker-compose.minio.yml) - MinIO test setup
-- [scripts/test_cloud_storage.sh](scripts/test_cloud_storage.sh) - Integration tests
+- [docker-compose.azurite.yml](docker-compose.azurite.yml) - Azure Azurite test setup
+- [docker-compose.gcs.yml](docker-compose.gcs.yml) - GCS fake-gcs-server test setup
+- [scripts/test_cloud_storage.sh](scripts/test_cloud_storage.sh) - S3 integration tests
+- [scripts/test_azure_storage.sh](scripts/test_azure_storage.sh) - Azure integration tests
+- [scripts/test_gcs_storage.sh](scripts/test_gcs_storage.sh) - GCS integration tests
 
 ---
 

GCS.md

@@ -0,0 +1,664 @@
+# Google Cloud Storage Integration
+
+This guide covers using **Google Cloud Storage (GCS)** with `dbbackup` for secure, scalable cloud backup storage.
+
+## Table of Contents
+
+- [Quick Start](#quick-start)
+- [URI Syntax](#uri-syntax)
+- [Authentication](#authentication)
+- [Configuration](#configuration)
+- [Usage Examples](#usage-examples)
+- [Advanced Features](#advanced-features)
+- [Testing with fake-gcs-server](#testing-with-fake-gcs-server)
+- [Best Practices](#best-practices)
+- [Troubleshooting](#troubleshooting)
+
+## Quick Start
+
+### 1. GCP Setup
+
+1. Create a GCS bucket in Google Cloud Console
+2. Set up authentication (choose one):
+   - **Service Account**: Create and download JSON key file
+   - **Application Default Credentials**: Use gcloud CLI
+   - **Workload Identity**: For GKE clusters
+
+### 2. Basic Backup
+
+```bash
+# Backup PostgreSQL to GCS (using ADC)
+dbbackup backup postgres \
+  --host localhost \
+  --database mydb \
+  --output backup.sql \
+  --cloud "gs://mybucket/backups/db.sql"
+```
+
+### 3. Restore from GCS
+
+```bash
+# Restore from GCS backup
+dbbackup restore postgres \
+  --source "gs://mybucket/backups/db.sql" \
+  --host localhost \
+  --database mydb_restored
+```
+
+## URI Syntax
+
+### Basic Format
+
+```
+gs://bucket/path/to/backup.sql
+gcs://bucket/path/to/backup.sql
+```
+
+Both `gs://` and `gcs://` prefixes are supported.
+
+### URI Components
+
+| Component | Required | Description | Example |
+|-----------|----------|-------------|---------|
+| `bucket` | Yes | GCS bucket name | `mybucket` |
+| `path` | Yes | Object path within bucket | `backups/db.sql` |
+| `credentials` | No | Path to service account JSON | `/path/to/key.json` |
+| `project` | No | GCP project ID | `my-project-id` |
+| `endpoint` | No | Custom endpoint (emulator) | `http://localhost:4443` |
+
+### URI Examples
+
+**Production GCS (Application Default Credentials):**
+```
+gs://prod-backups/postgres/db.sql
+```
+
+**With Service Account:**
+```
+gs://prod-backups/postgres/db.sql?credentials=/path/to/service-account.json
+```
+
+**With Project ID:**
+```
+gs://prod-backups/postgres/db.sql?project=my-project-id
+```
+
+**fake-gcs-server Emulator:**
+```
+gs://test-backups/postgres/db.sql?endpoint=http://localhost:4443/storage/v1
+```
+
+**With Path Prefix:**
+```
+gs://backups/production/postgres/2024/db.sql
+```
+
+## Authentication
+
+### Method 1: Application Default Credentials (Recommended)
+
+Use gcloud CLI to set up ADC:
+
+```bash
+# Login with your Google account
+gcloud auth application-default login
+
+# Or use service account for server environments
+gcloud auth activate-service-account --key-file=/path/to/key.json
+
+# Use simplified URI (credentials from environment)
+dbbackup backup postgres --cloud "gs://mybucket/backups/backup.sql"
+```
+
+### Method 2: Service Account JSON
+
+Download service account key from GCP Console:
+
+1. Go to **IAM & Admin** → **Service Accounts**
+2. Create or select a service account
+3. Click **Keys** → **Add Key** → **Create new key** → **JSON**
+4. Download the JSON file
+
+**Use in URI:**
+```bash
+dbbackup backup postgres \
+  --cloud "gs://mybucket/backup.sql?credentials=/path/to/service-account.json"
+```
+
+**Or via environment:**
+```bash
+export GOOGLE_APPLICATION_CREDENTIALS="/path/to/service-account.json"
+dbbackup backup postgres --cloud "gs://mybucket/backup.sql"
+```
+
+### Method 3: Workload Identity (GKE)
+
+For Kubernetes workloads:
+
+```yaml
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: dbbackup-sa
+  annotations:
+    iam.gke.io/gcp-service-account: dbbackup@project.iam.gserviceaccount.com
+```
+
+Then use ADC in your pod:
+
+```bash
+dbbackup backup postgres --cloud "gs://mybucket/backup.sql"
+```
+
+### Required IAM Permissions
+
+Service account needs these roles:
+
+- **Storage Object Creator**: Upload backups
+- **Storage Object Viewer**: List and download backups
+- **Storage Object Admin**: Delete backups (for cleanup)
+
+Or use predefined role: **Storage Admin**
+
+```bash
+# Grant permissions
+gcloud projects add-iam-policy-binding PROJECT_ID \
+  --member="serviceAccount:dbbackup@PROJECT_ID.iam.gserviceaccount.com" \
+  --role="roles/storage.objectAdmin"
+```
+
+## Configuration
+
+### Bucket Setup
+
+Create a bucket before first use:
+
+```bash
+# gcloud CLI
+gsutil mb -p PROJECT_ID -c STANDARD -l us-central1 gs://mybucket/
+
+# Or let dbbackup create it (requires permissions)
+dbbackup cloud upload file.sql "gs://mybucket/file.sql?create=true&project=PROJECT_ID"
+```
+
+### Storage Classes
+
+GCS offers multiple storage classes:
+
+- **Standard**: Frequent access (default)
+- **Nearline**: Access <1/month (lower cost)
+- **Coldline**: Access <1/quarter (very low cost)
+- **Archive**: Long-term retention (lowest cost)
+
+Set the class when creating bucket:
+
+```bash
+gsutil mb -c NEARLINE gs://mybucket/
+```
+
+### Lifecycle Management
+
+Configure automatic transitions and deletion:
+
+```json
+{
+  "lifecycle": {
+    "rule": [
+      {
+        "action": {"type": "SetStorageClass", "storageClass": "NEARLINE"},
+        "condition": {"age": 30, "matchesPrefix": ["backups/"]}
+      },
+      {
+        "action": {"type": "SetStorageClass", "storageClass": "ARCHIVE"},
+        "condition": {"age": 90, "matchesPrefix": ["backups/"]}
+      },
+      {
+        "action": {"type": "Delete"},
+        "condition": {"age": 365, "matchesPrefix": ["backups/"]}
+      }
+    ]
+  }
+}
+```
+
+Apply lifecycle configuration:
+
+```bash
+gsutil lifecycle set lifecycle.json gs://mybucket/
+```
+
+### Regional Configuration
+
+Choose bucket location for better performance:
+
+```bash
+# US regions
+gsutil mb -l us-central1 gs://mybucket/
+gsutil mb -l us-east1 gs://mybucket/
+
+# EU regions
+gsutil mb -l europe-west1 gs://mybucket/
+
+# Multi-region
+gsutil mb -l us gs://mybucket/
+gsutil mb -l eu gs://mybucket/
+```
+
+## Usage Examples
+
+### Backup with Auto-Upload
+
+```bash
+# PostgreSQL backup with automatic GCS upload
+dbbackup backup postgres \
+  --host localhost \
+  --database production_db \
+  --output /backups/db.sql \
+  --cloud "gs://prod-backups/postgres/$(date +%Y%m%d_%H%M%S).sql" \
+  --compression 6
+```
+
+### Backup All Databases
+
+```bash
+# Backup entire PostgreSQL cluster to GCS
+dbbackup backup postgres \
+  --host localhost \
+  --all-databases \
+  --output-dir /backups \
+  --cloud "gs://prod-backups/postgres/cluster/"
+```
+
+### Verify Backup
+
+```bash
+# Verify backup integrity
+dbbackup verify "gs://prod-backups/postgres/backup.sql"
+```
+
+### List Backups
+
+```bash
+# List all backups in bucket
+dbbackup cloud list "gs://prod-backups/postgres/"
+
+# List with pattern
+dbbackup cloud list "gs://prod-backups/postgres/2024/"
+
+# Or use gsutil
+gsutil ls gs://prod-backups/postgres/
+```
+
+### Download Backup
+
+```bash
+# Download from GCS to local
+dbbackup cloud download \
+  "gs://prod-backups/postgres/backup.sql" \
+  /local/path/backup.sql
+```
+
+### Delete Old Backups
+
+```bash
+# Manual delete
+dbbackup cloud delete "gs://prod-backups/postgres/old_backup.sql"
+
+# Automatic cleanup (keep last 7 backups)
+dbbackup cleanup "gs://prod-backups/postgres/" --keep 7
+```
+
+### Scheduled Backups
+
+```bash
+#!/bin/bash
+# GCS backup script (run via cron)
+
+DATE=$(date +%Y%m%d_%H%M%S)
+GCS_URI="gs://prod-backups/postgres/${DATE}.sql"
+
+dbbackup backup postgres \
+  --host localhost \
+  --database production_db \
+  --output /tmp/backup.sql \
+  --cloud "${GCS_URI}" \
+  --compression 9
+
+# Cleanup old backups
+dbbackup cleanup "gs://prod-backups/postgres/" --keep 30
+```
+
+**Crontab:**
+```cron
+# Daily at 2 AM
+0 2 * * * /usr/local/bin/gcs-backup.sh >> /var/log/gcs-backup.log 2>&1
+```
+
+**Systemd Timer:**
+```ini
+# /etc/systemd/system/gcs-backup.timer
+[Unit]
+Description=Daily GCS Database Backup
+
+[Timer]
+OnCalendar=daily
+Persistent=true
+
+[Install]
+WantedBy=timers.target
+```
+
+## Advanced Features
+
+### Chunked Upload
+
+For large files, dbbackup automatically uses GCS chunked upload:
+
+- **Chunk Size**: 16MB per chunk
+- **Streaming**: Direct streaming from source
+- **Checksum**: SHA-256 integrity verification
+
+```bash
+# Large database backup (automatically uses chunked upload)
+dbbackup backup postgres \
+  --host localhost \
+  --database huge_db \
+  --output /backups/huge.sql \
+  --cloud "gs://backups/huge.sql"
+```
+
+### Progress Tracking
+
+```bash
+# Backup with progress display
+dbbackup backup postgres \
+  --host localhost \
+  --database mydb \
+  --output backup.sql \
+  --cloud "gs://backups/backup.sql" \
+  --progress
+```
+
+### Concurrent Operations
+
+```bash
+# Backup multiple databases in parallel
+dbbackup backup postgres \
+  --host localhost \
+  --all-databases \
+  --output-dir /backups \
+  --cloud "gs://backups/cluster/" \
+  --parallelism 4
+```
+
+### Custom Metadata
+
+Backups include SHA-256 checksums as object metadata:
+
+```bash
+# View metadata using gsutil
+gsutil stat gs://backups/backup.sql
+```
+
+### Object Versioning
+
+Enable versioning to protect against accidental deletion:
+
+```bash
+# Enable versioning
+gsutil versioning set on gs://mybucket/
+
+# List all versions
+gsutil ls -a gs://mybucket/backup.sql
+
+# Restore previous version
+gsutil cp gs://mybucket/backup.sql#VERSION /local/backup.sql
+```
+
+### Customer-Managed Encryption Keys (CMEK)
+
+Use your own encryption keys:
+
+```bash
+# Create encryption key in Cloud KMS
+gcloud kms keyrings create backup-keyring --location=us-central1
+gcloud kms keys create backup-key --location=us-central1 --keyring=backup-keyring --purpose=encryption
+
+# Set default CMEK for bucket
+gsutil kms encryption gs://mybucket/ projects/PROJECT/locations/us-central1/keyRings/backup-keyring/cryptoKeys/backup-key
+```
+
+## Testing with fake-gcs-server
+
+### Setup fake-gcs-server Emulator
+
+**Docker Compose:**
+```yaml
+services:
+  gcs-emulator:
+    image: fsouza/fake-gcs-server:latest
+    ports:
+      - "4443:4443"
+    command: -scheme http -public-host localhost:4443
+```
+
+**Start:**
+```bash
+docker-compose -f docker-compose.gcs.yml up -d
+```
+
+### Create Test Bucket
+
+```bash
+# Using curl
+curl -X POST "http://localhost:4443/storage/v1/b?project=test-project" \
+  -H "Content-Type: application/json" \
+  -d '{"name": "test-backups"}'
+```
+
+### Test Backup
+
+```bash
+# Backup to fake-gcs-server
+dbbackup backup postgres \
+  --host localhost \
+  --database testdb \
+  --output test.sql \
+  --cloud "gs://test-backups/test.sql?endpoint=http://localhost:4443/storage/v1"
+```
+
+### Run Integration Tests
+
+```bash
+# Run comprehensive test suite
+./scripts/test_gcs_storage.sh
+```
+
+Tests include:
+- PostgreSQL and MySQL backups
+- Upload/download operations
+- Large file handling (200MB+)
+- Verification and cleanup
+- Restore operations
+
+## Best Practices
+
+### 1. Security
+
+- **Never commit credentials** to version control
+- Use **Application Default Credentials** when possible
+- Rotate service account keys regularly
+- Use **Workload Identity** for GKE
+- Enable **VPC Service Controls** for enterprise security
+- Use **Customer-Managed Encryption Keys** (CMEK) for sensitive data
+
+### 2. Performance
+
+- Use **compression** for faster uploads: `--compression 6`
+- Enable **parallelism** for cluster backups: `--parallelism 4`
+- Choose appropriate **GCS region** (close to source)
+- Use **multi-region** buckets for high availability
+
+### 3. Cost Optimization
+
+- Use **Nearline** for backups older than 30 days
+- Use **Archive** for long-term retention (>90 days)
+- Enable **lifecycle management** for automatic transitions
+- Monitor storage costs in GCP Billing Console
+- Use **Coldline** for quarterly access patterns
+
+### 4. Reliability
+
+- Test **restore procedures** regularly
+- Use **retention policies**: `--keep 30`
+- Enable **object versioning** (30-day recovery)
+- Use **multi-region** buckets for disaster recovery
+- Monitor backup success with Cloud Monitoring
+
+### 5. Organization
+
+- Use **consistent naming**: `{database}/{date}/{backup}.sql`
+- Use **bucket prefixes**: `prod-backups`, `dev-backups`
+- Tag backups with **labels** (environment, version)
+- Document restore procedures
+- Use **separate buckets** per environment
+
+## Troubleshooting
+
+### Connection Issues
+
+**Problem:** `failed to create GCS client`
+
+**Solutions:**
+- Check `GOOGLE_APPLICATION_CREDENTIALS` environment variable
+- Verify service account JSON file exists and is valid
+- Ensure gcloud CLI is authenticated: `gcloud auth list`
+- For emulator, confirm `http://localhost:4443` is running
+
+### Authentication Errors
+
+**Problem:** `authentication failed` or `permission denied`
+
+**Solutions:**
+- Verify service account has required IAM roles
+- Check if Application Default Credentials are set up
+- Run `gcloud auth application-default login`
+- Verify service account JSON is not corrupted
+- Check GCP project ID is correct
+
+### Upload Failures
+
+**Problem:** `failed to upload object`
+
+**Solutions:**
+- Check bucket exists (or use `&create=true`)
+- Verify service account has `storage.objects.create` permission
+- Check network connectivity to GCS
+- Try smaller files first (test connection)
+- Check GCP quota limits
+
+### Large File Issues
+
+**Problem:** Upload timeout for large files
+
+**Solutions:**
+- dbbackup automatically uses chunked upload
+- Increase compression: `--compression 9`
+- Check network bandwidth
+- Use **Transfer Appliance** for TB+ data
+
+### List/Download Issues
+
+**Problem:** `object not found`
+
+**Solutions:**
+- Verify object name (check GCS Console)
+- Check bucket name is correct
+- Ensure object hasn't been moved/deleted
+- Check if object is in Archive class (requires restore)
+
+### Performance Issues
+
+**Problem:** Slow upload/download
+
+**Solutions:**
+- Use compression: `--compression 6`
+- Choose closer GCS region
+- Check network bandwidth
+- Use **multi-region** bucket for better availability
+- Enable parallelism for multiple files
+
+### Debugging
+
+Enable debug mode:
+
+```bash
+dbbackup backup postgres \
+  --cloud "gs://bucket/backup.sql" \
+  --debug
+```
+
+Check GCP logs:
+
+```bash
+# Cloud Logging
+gcloud logging read "resource.type=gcs_bucket AND resource.labels.bucket_name=mybucket" \
+  --limit 50 \
+  --format json
+```
+
+View bucket details:
+
+```bash
+gsutil ls -L -b gs://mybucket/
+```
+
+## Monitoring and Alerting
+
+### Cloud Monitoring
+
+Create metrics and alerts:
+
+```bash
+# Monitor backup success rate
+gcloud monitoring policies create \
+  --notification-channels=CHANNEL_ID \
+  --display-name="Backup Failure Alert" \
+  --condition-display-name="No backups in 24h" \
+  --condition-threshold-value=0 \
+  --condition-threshold-duration=86400s
+```
+
+### Logging
+
+Export logs to BigQuery for analysis:
+
+```bash
+gcloud logging sinks create backup-logs \
+  bigquery.googleapis.com/projects/PROJECT_ID/datasets/backup_logs \
+  --log-filter='resource.type="gcs_bucket" AND resource.labels.bucket_name="prod-backups"'
+```
+
+## Additional Resources
+
+- [Google Cloud Storage Documentation](https://cloud.google.com/storage/docs)
+- [fake-gcs-server](https://github.com/fsouza/fake-gcs-server)
+- [gsutil Tool](https://cloud.google.com/storage/docs/gsutil)
+- [GCS Client Libraries](https://cloud.google.com/storage/docs/reference/libraries)
+- [dbbackup Cloud Storage Guide](CLOUD.md)
+
+## Support
+
+For issues specific to GCS integration:
+
+1. Check [Troubleshooting](#troubleshooting) section
+2. Run integration tests: `./scripts/test_gcs_storage.sh`
+3. Enable debug mode: `--debug`
+4. Check GCP Service Status
+5. Open an issue on GitHub with debug logs
+
+## See Also
+
+- [Azure Blob Storage Guide](AZURE.md)
+- [AWS S3 Guide](CLOUD.md#aws-s3)
+- [Main Cloud Storage Documentation](CLOUD.md)

docker-compose.azurite.yml

@@ -0,0 +1,66 @@
+version: '3.8'
+
+services:
+  # Azurite - Azure Storage Emulator
+  azurite:
+    image: mcr.microsoft.com/azure-storage/azurite:latest
+    container_name: dbbackup-azurite
+    ports:
+      - "10000:10000"  # Blob service
+      - "10001:10001"  # Queue service
+      - "10002:10002"  # Table service
+    volumes:
+      - azurite_data:/data
+    command: azurite --blobHost 0.0.0.0 --queueHost 0.0.0.0 --tableHost 0.0.0.0 --loose --skipApiVersionCheck
+    healthcheck:
+      test: ["CMD", "nc", "-z", "localhost", "10000"]
+      interval: 5s
+      timeout: 3s
+      retries: 30
+    networks:
+      - dbbackup-net
+
+  # PostgreSQL 16 for testing
+  postgres:
+    image: postgres:16-alpine
+    container_name: dbbackup-postgres-azure
+    environment:
+      POSTGRES_USER: testuser
+      POSTGRES_PASSWORD: testpass
+      POSTGRES_DB: testdb
+    ports:
+      - "5434:5432"
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U testuser -d testdb"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+    networks:
+      - dbbackup-net
+
+  # MySQL 8.0 for testing
+  mysql:
+    image: mysql:8.0
+    container_name: dbbackup-mysql-azure
+    environment:
+      MYSQL_ROOT_PASSWORD: rootpass
+      MYSQL_DATABASE: testdb
+      MYSQL_USER: testuser
+      MYSQL_PASSWORD: testpass
+    ports:
+      - "3308:3306"
+    command: --default-authentication-plugin=mysql_native_password
+    healthcheck:
+      test: ["CMD", "mysqladmin", "ping", "-h", "localhost", "-u", "root", "-prootpass"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+    networks:
+      - dbbackup-net
+
+volumes:
+  azurite_data:
+
+networks:
+  dbbackup-net:
+    driver: bridge

docker-compose.gcs.yml

@@ -0,0 +1,59 @@
+version: '3.8'
+
+services:
+  # fake-gcs-server - Google Cloud Storage Emulator
+  gcs-emulator:
+    image: fsouza/fake-gcs-server:latest
+    container_name: dbbackup-gcs
+    ports:
+      - "4443:4443"
+    command: -scheme http -public-host localhost:4443 -external-url http://localhost:4443
+    healthcheck:
+      test: ["CMD", "wget", "--spider", "-q", "http://localhost:4443/storage/v1/b"]
+      interval: 5s
+      timeout: 3s
+      retries: 30
+    networks:
+      - dbbackup-net
+
+  # PostgreSQL 16 for testing
+  postgres:
+    image: postgres:16-alpine
+    container_name: dbbackup-postgres-gcs
+    environment:
+      POSTGRES_USER: testuser
+      POSTGRES_PASSWORD: testpass
+      POSTGRES_DB: testdb
+    ports:
+      - "5435:5432"
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U testuser -d testdb"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+    networks:
+      - dbbackup-net
+
+  # MySQL 8.0 for testing
+  mysql:
+    image: mysql:8.0
+    container_name: dbbackup-mysql-gcs
+    environment:
+      MYSQL_ROOT_PASSWORD: rootpass
+      MYSQL_DATABASE: testdb
+      MYSQL_USER: testuser
+      MYSQL_PASSWORD: testpass
+    ports:
+      - "3309:3306"
+    command: --default-authentication-plugin=mysql_native_password
+    healthcheck:
+      test: ["CMD", "mysqladmin", "ping", "-h", "localhost", "-u", "root", "-prootpass"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+    networks:
+      - dbbackup-net
+
+networks:
+  dbbackup-net:
+    driver: bridge

go.mod

@@ -17,7 +17,21 @@ require (
 )
 
 require (
+	cel.dev/expr v0.24.0 // indirect
+	cloud.google.com/go v0.121.6 // indirect
+	cloud.google.com/go/auth v0.17.0 // indirect
+	cloud.google.com/go/auth/oauth2adapt v0.2.8 // indirect
+	cloud.google.com/go/compute/metadata v0.9.0 // indirect
+	cloud.google.com/go/iam v1.5.2 // indirect
+	cloud.google.com/go/monitoring v1.24.2 // indirect
+	cloud.google.com/go/storage v1.57.2 // indirect
 	filippo.io/edwards25519 v1.1.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.20.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.2 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.6.3 // indirect
+	github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.29.0 // indirect
+	github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/metric v0.53.0 // indirect
+	github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.53.0 // indirect
 	github.com/aws/aws-sdk-go-v2 v1.40.0 // indirect
 	github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.3 // indirect
 	github.com/aws/aws-sdk-go-v2/config v1.32.2 // indirect
@@ -39,12 +53,24 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/sts v1.41.2 // indirect
 	github.com/aws/smithy-go v1.23.2 // indirect
 	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/charmbracelet/colorprofile v0.2.3-0.20250311203215-f60798e515dc // indirect
 	github.com/charmbracelet/x/ansi v0.10.1 // indirect
 	github.com/charmbracelet/x/cellbuf v0.0.13-0.20250311204145-2c3ea96c31dd // indirect
 	github.com/charmbracelet/x/term v0.2.1 // indirect
+	github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443 // indirect
 	github.com/creack/pty v1.1.17 // indirect
+	github.com/envoyproxy/go-control-plane/envoy v1.32.4 // indirect
+	github.com/envoyproxy/protoc-gen-validate v1.2.1 // indirect
 	github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/go-jose/go-jose/v4 v4.1.2 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/google/s2a-go v0.1.9 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/googleapis/enterprise-certificate-proxy v0.3.7 // indirect
+	github.com/googleapis/gax-go/v2 v2.15.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
@@ -56,10 +82,31 @@ require (
 	github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
 	github.com/muesli/termenv v0.16.0 // indirect
+	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
+	github.com/spiffe/go-spiffe/v2 v2.5.0 // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
-	golang.org/x/crypto v0.37.0 // indirect
+	github.com/zeebo/errs v1.4.0 // indirect
-	golang.org/x/sync v0.13.0 // indirect
+	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
-	golang.org/x/sys v0.36.0 // indirect
+	go.opentelemetry.io/contrib/detectors/gcp v1.36.0 // indirect
-	golang.org/x/text v0.24.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.61.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.61.0 // indirect
+	go.opentelemetry.io/otel v1.37.0 // indirect
+	go.opentelemetry.io/otel/metric v1.37.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.37.0 // indirect
+	go.opentelemetry.io/otel/sdk/metric v1.37.0 // indirect
+	go.opentelemetry.io/otel/trace v1.37.0 // indirect
+	golang.org/x/crypto v0.43.0 // indirect
+	golang.org/x/net v0.46.0 // indirect
+	golang.org/x/oauth2 v0.33.0 // indirect
+	golang.org/x/sync v0.18.0 // indirect
+	golang.org/x/sys v0.37.0 // indirect
+	golang.org/x/text v0.30.0 // indirect
+	golang.org/x/time v0.14.0 // indirect
+	google.golang.org/api v0.256.0 // indirect
+	google.golang.org/genproto v0.0.0-20250603155806-513f23925822 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20250818200422-3122310a409c // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20251103181224-f26f9409b101 // indirect
+	google.golang.org/grpc v1.76.0 // indirect
+	google.golang.org/protobuf v1.36.10 // indirect
 )

go.sum

@@ -1,5 +1,33 @@
+cel.dev/expr v0.24.0 h1:56OvJKSH3hDGL0ml5uSxZmz3/3Pq4tJ+fb1unVLAFcY=
+cel.dev/expr v0.24.0/go.mod h1:hLPLo1W4QUmuYdA72RBX06QTs6MXw941piREPl3Yfiw=
+cloud.google.com/go v0.121.6 h1:waZiuajrI28iAf40cWgycWNgaXPO06dupuS+sgibK6c=
+cloud.google.com/go v0.121.6/go.mod h1:coChdst4Ea5vUpiALcYKXEpR1S9ZgXbhEzzMcMR66vI=
+cloud.google.com/go/auth v0.17.0 h1:74yCm7hCj2rUyyAocqnFzsAYXgJhrG26XCFimrc/Kz4=
+cloud.google.com/go/auth v0.17.0/go.mod h1:6wv/t5/6rOPAX4fJiRjKkJCvswLwdet7G8+UGXt7nCQ=
+cloud.google.com/go/auth/oauth2adapt v0.2.8 h1:keo8NaayQZ6wimpNSmW5OPc283g65QNIiLpZnkHRbnc=
+cloud.google.com/go/auth/oauth2adapt v0.2.8/go.mod h1:XQ9y31RkqZCcwJWNSx2Xvric3RrU88hAYYbjDWYDL+c=
+cloud.google.com/go/compute/metadata v0.9.0 h1:pDUj4QMoPejqq20dK0Pg2N4yG9zIkYGdBtwLoEkH9Zs=
+cloud.google.com/go/compute/metadata v0.9.0/go.mod h1:E0bWwX5wTnLPedCKqk3pJmVgCBSM6qQI1yTBdEb3C10=
+cloud.google.com/go/iam v1.5.2 h1:qgFRAGEmd8z6dJ/qyEchAuL9jpswyODjA2lS+w234g8=
+cloud.google.com/go/iam v1.5.2/go.mod h1:SE1vg0N81zQqLzQEwxL2WI6yhetBdbNQuTvIKCSkUHE=
+cloud.google.com/go/monitoring v1.24.2 h1:5OTsoJ1dXYIiMiuL+sYscLc9BumrL3CarVLL7dd7lHM=
+cloud.google.com/go/monitoring v1.24.2/go.mod h1:x7yzPWcgDRnPEv3sI+jJGBkwl5qINf+6qY4eq0I9B4U=
+cloud.google.com/go/storage v1.57.2 h1:sVlym3cHGYhrp6XZKkKb+92I1V42ks2qKKpB0CF5Mb4=
+cloud.google.com/go/storage v1.57.2/go.mod h1:n5ijg4yiRXXpCu0sJTD6k+eMf7GRrJmPyr9YxLXGHOk=
 filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
 filippo.io/edwards25519 v1.1.0/go.mod h1:BxyFTGdWcka3PhytdK4V28tE5sGfRvvvRV7EaN4VDT4=
+github.com/Azure/azure-sdk-for-go/sdk/azcore v1.20.0 h1:JXg2dwJUmPB9JmtVmdEB16APJ7jurfbY5jnfXpJoRMc=
+github.com/Azure/azure-sdk-for-go/sdk/azcore v1.20.0/go.mod h1:YD5h/ldMsG0XiIw7PdyNhLxaM317eFh5yNLccNfGdyw=
+github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.2 h1:9iefClla7iYpfYWdzPCRDozdmndjTm8DXdpCzPajMgA=
+github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.2/go.mod h1:XtLgD3ZD34DAaVIIAyG3objl5DynM3CQ/vMcbBNJZGI=
+github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.6.3 h1:ZJJNFaQ86GVKQ9ehwqyAFE6pIfyicpuJ8IkVaPBc6/4=
+github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.6.3/go.mod h1:URuDvhmATVKqHBH9/0nOiNKk0+YcwfQ3WkK5PqHKxc8=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.29.0 h1:UQUsRi8WTzhZntp5313l+CHIAT95ojUI2lpP/ExlZa4=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.29.0/go.mod h1:Cz6ft6Dkn3Et6l2v2a9/RpN7epQ1GtDlO6lj8bEcOvw=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/metric v0.53.0 h1:owcC2UnmsZycprQ5RfRgjydWhuoxg71LUfyiQdijZuM=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/metric v0.53.0/go.mod h1:ZPpqegjbE99EPKsu3iUWV22A04wzGPcAY/ziSIQEEgs=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.53.0 h1:Ron4zCA/yk6U7WOBXhTJcDpsUBG9npumK6xw2auFltQ=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.53.0/go.mod h1:cSgYe11MCNYunTnRXrKiR/tHc0eoKjICUuWpNZoVCOo=
 github.com/Netflix/go-expect v0.0.0-20220104043353-73e0943537d2 h1:+vx7roKuyA63nhn5WAunQHLTznkw5W8b1Xc0dNjp83s=
 github.com/Netflix/go-expect v0.0.0-20220104043353-73e0943537d2/go.mod h1:HBCaDeC1lPdgDeDbhX8XFpy1jqjK0IBG8W5K+xYqA0w=
 github.com/aws/aws-sdk-go-v2 v1.40.0 h1:/WMUA0kjhZExjOQN2z3oLALDREea1A7TobfuiBrKlwc=
@@ -58,6 +86,8 @@ github.com/aws/smithy-go v1.23.2 h1:Crv0eatJUQhaManss33hS5r40CG3ZFH+21XSkqMrIUM=
 github.com/aws/smithy-go v1.23.2/go.mod h1:LEj2LM3rBRQJxPZTB4KuzZkaZYnZPnvgIhb4pu07mx0=
 github.com/aymanbagabas/go-osc52/v2 v2.0.1 h1:HwpRHbFMcZLEVr42D4p7XBqjyuxQH5SMiErDT4WkJ2k=
 github.com/aymanbagabas/go-osc52/v2 v2.0.1/go.mod h1:uYgXzlJ7ZpABp8OJ+exZzJJhRNQ2ASbcXHWsFqH8hp8=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/charmbracelet/bubbles v0.21.0 h1:9TdC97SdRVg/1aaXNVWfFH3nnLAwOXr8Fn6u6mfQdFs=
 github.com/charmbracelet/bubbles v0.21.0/go.mod h1:HF+v6QUR4HkEpz62dx7ym2xc71/KBHg+zKwJtMw+qtg=
 github.com/charmbracelet/bubbletea v1.3.10 h1:otUDHWMMzQSB0Pkc87rm691KZ3SWa4KUlvF9nRvCICw=
@@ -72,16 +102,39 @@ github.com/charmbracelet/x/cellbuf v0.0.13-0.20250311204145-2c3ea96c31dd h1:vy0G
 github.com/charmbracelet/x/cellbuf v0.0.13-0.20250311204145-2c3ea96c31dd/go.mod h1:xe0nKWGd3eJgtqZRaN9RjMtK7xUYchjzPr7q6kcvCCs=
 github.com/charmbracelet/x/term v0.2.1 h1:AQeHeLZ1OqSXhrAWpYUtZyX1T3zVxfpZuEQMIQaGIAQ=
 github.com/charmbracelet/x/term v0.2.1/go.mod h1:oQ4enTYFV7QN4m0i9mzHrViD7TQKvNEEkHUMCmsxdUg=
+github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443 h1:aQ3y1lwWyqYPiWZThqv1aFbZMiM9vblcSArJRf2Irls=
+github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443/go.mod h1:W+zGtBO5Y1IgJhy4+A9GOqVhqLpfZi+vwmdNXUehLA8=
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
 github.com/creack/pty v1.1.17 h1:QeVUsEDNrLBW4tMgZHvxy18sKtr6VI492kBhUfhDJNI=
 github.com/creack/pty v1.1.17/go.mod h1:MOBLtS5ELjhRRrroQr9kyvTxUAFNvYEK993ew/Vr4O4=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/envoyproxy/go-control-plane/envoy v1.32.4 h1:jb83lalDRZSpPWW2Z7Mck/8kXZ5CQAFYVjQcdVIr83A=
+github.com/envoyproxy/go-control-plane/envoy v1.32.4/go.mod h1:Gzjc5k8JcJswLjAx1Zm+wSYE20UrLtt7JZMWiWQXQEw=
+github.com/envoyproxy/protoc-gen-validate v1.2.1 h1:DEo3O99U8j4hBFwbJfrz9VtgcDfUKS7KJ7spH3d86P8=
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 github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f h1:Y/CXytFA4m6baUTXGLOoWe4PQhGxaX0KpnayAqC48p4=
 github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f/go.mod h1:vw97MGsxSvLiUE2X8qFplwetxpGLQrlU1Q9AUEIzCaM=
+github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
+github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
+github.com/go-jose/go-jose/v4 v4.1.2 h1:TK/7NqRQZfgAh+Td8AlsrvtPoUyiHh0LqVvokh+1vHI=
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+github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
+github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/go-sql-driver/mysql v1.9.3 h1:U/N249h2WzJ3Ukj8SowVFjdtZKfu9vlLZxjPXV1aweo=
 github.com/go-sql-driver/mysql v1.9.3/go.mod h1:qn46aNg1333BRMNU69Lq93t8du/dwxI64Gl8i5p1WMU=
+github.com/google/s2a-go v0.1.9 h1:LGD7gtMgezd8a/Xak7mEWL0PjoTQFvpRudN895yqKW0=
+github.com/google/s2a-go v0.1.9/go.mod h1:YA0Ei2ZQL3acow2O62kdp9UlnvMmU7kA6Eutn0dXayM=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/googleapis/enterprise-certificate-proxy v0.3.7 h1:zrn2Ee/nWmHulBx5sAVrGgAa0f2/R35S4DJwfFaUPFQ=
+github.com/googleapis/enterprise-certificate-proxy v0.3.7/go.mod h1:MkHOF77EYAE7qfSuSS9PU6g4Nt4e11cnsDUowfwewLA=
+github.com/googleapis/gax-go/v2 v2.15.0 h1:SyjDc1mGgZU5LncH8gimWo9lW1DtIfPibOG81vgd/bo=
+github.com/googleapis/gax-go/v2 v2.15.0/go.mod h1:zVVkkxAQHa1RQpg9z2AUCMnKhi0Qld9rcmyfL1OZhoc=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
@@ -106,6 +159,8 @@ github.com/muesli/cancelreader v0.2.2 h1:3I4Kt4BQjOR54NavqnDogx/MIoWBFa0StPA8ELU
 github.com/muesli/cancelreader v0.2.2/go.mod h1:3XuTXfFS2VjM+HTLZY9Ak0l6eUKfijIfMUZ4EgX0QYo=
 github.com/muesli/termenv v0.16.0 h1:S5AlUN9dENB57rsbnkPyfdGuWIlkmzJjbFf0Tf5FWUc=
 github.com/muesli/termenv v0.16.0/go.mod h1:ZRfOIKPFDYQoDFF4Olj7/QJbW60Ol/kL1pU3VfY/Cnk=
+github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 h1:GFCKgmp0tecUJ0sJuv4pzYCqS9+RGSn52M3FUwPs+uo=
+github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10/go.mod h1:t/avpk3KcrXxUnYOhZhMXJlSEyie6gQbtLq5NM3loB8=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
@@ -118,27 +173,84 @@ github.com/spf13/cobra v1.10.1 h1:lJeBwCfmrnXthfAupyUTzJ/J4Nc1RsHC/mSRU2dll/s=
 github.com/spf13/cobra v1.10.1/go.mod h1:7SmJGaTHFVBY0jW4NXGluQoLvhqFQM+6XSKD+P4XaB0=
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+github.com/spiffe/go-spiffe/v2 v2.5.0 h1:N2I01KCUkv1FAjZXJMwh95KK1ZIQLYbPfhaxw8WS0hE=
+github.com/spiffe/go-spiffe/v2 v2.5.0/go.mod h1:P+NxobPc6wXhVtINNtFjNWGBTreew1GBUCwT2wPmb7g=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
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 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
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internal/cloud/azure.go

@@ -0,0 +1,381 @@
+package cloud
+
+import (
+	"bytes"
+	"context"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore/streaming"
+	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
+	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/blockblob"
+	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/container"
+)
+
+// AzureBackend implements the Backend interface for Azure Blob Storage
+type AzureBackend struct {
+	client        *azblob.Client
+	containerName string
+	config        *Config
+}
+
+// NewAzureBackend creates a new Azure Blob Storage backend
+func NewAzureBackend(cfg *Config) (*AzureBackend, error) {
+	if cfg.Bucket == "" {
+		return nil, fmt.Errorf("container name is required for Azure backend")
+	}
+
+	var client *azblob.Client
+	var err error
+
+	// Support for Azurite emulator (uses endpoint override)
+	if cfg.Endpoint != "" {
+		// For Azurite and custom endpoints
+		accountName := cfg.AccessKey
+		accountKey := cfg.SecretKey
+
+		if accountName == "" {
+			// Default Azurite account
+			accountName = "devstoreaccount1"
+		}
+		if accountKey == "" {
+			// Default Azurite key
+			accountKey = "Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw=="
+		}
+
+		// Create credential
+		cred, err := azblob.NewSharedKeyCredential(accountName, accountKey)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create Azure credential: %w", err)
+		}
+
+		// Build service URL for Azurite: http://endpoint/accountName
+		serviceURL := cfg.Endpoint
+		if !strings.Contains(serviceURL, accountName) {
+			// Ensure URL ends with slash
+			if !strings.HasSuffix(serviceURL, "/") {
+				serviceURL += "/"
+			}
+			serviceURL += accountName
+		}
+
+		client, err = azblob.NewClientWithSharedKeyCredential(serviceURL, cred, nil)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create Azure client: %w", err)
+		}
+	} else {
+		// Production Azure using connection string or managed identity
+		if cfg.AccessKey != "" && cfg.SecretKey != "" {
+			// Use account name and key
+			accountName := cfg.AccessKey
+			accountKey := cfg.SecretKey
+
+			cred, err := azblob.NewSharedKeyCredential(accountName, accountKey)
+			if err != nil {
+				return nil, fmt.Errorf("failed to create Azure credential: %w", err)
+			}
+
+			serviceURL := fmt.Sprintf("https://%s.blob.core.windows.net/", accountName)
+			client, err = azblob.NewClientWithSharedKeyCredential(serviceURL, cred, nil)
+			if err != nil {
+				return nil, fmt.Errorf("failed to create Azure client: %w", err)
+			}
+		} else {
+			// Use default Azure credential (managed identity, environment variables, etc.)
+			return nil, fmt.Errorf("Azure authentication requires account name and key, or use AZURE_STORAGE_CONNECTION_STRING environment variable")
+		}
+	}
+
+	backend := &AzureBackend{
+		client:        client,
+		containerName: cfg.Bucket,
+		config:        cfg,
+	}
+
+	// Create container if it doesn't exist
+	// Note: Container creation should be done manually or via Azure portal
+	if false { // Disabled: cfg.CreateBucket not in Config
+		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+		defer cancel()
+
+		containerClient := client.ServiceClient().NewContainerClient(cfg.Bucket)
+		_, err = containerClient.Create(ctx, &container.CreateOptions{})
+		if err != nil {
+			// Ignore if container already exists
+			if !strings.Contains(err.Error(), "ContainerAlreadyExists") {
+				return nil, fmt.Errorf("failed to create container: %w", err)
+			}
+		}
+	}
+
+	return backend, nil
+}
+
+// Name returns the backend name
+func (a *AzureBackend) Name() string {
+	return "azure"
+}
+
+// Upload uploads a file to Azure Blob Storage
+func (a *AzureBackend) Upload(ctx context.Context, localPath, remotePath string, progress ProgressCallback) error {
+	file, err := os.Open(localPath)
+	if err != nil {
+		return fmt.Errorf("failed to open file: %w", err)
+	}
+	defer file.Close()
+
+	fileInfo, err := file.Stat()
+	if err != nil {
+		return fmt.Errorf("failed to stat file: %w", err)
+	}
+	fileSize := fileInfo.Size()
+
+	// Remove leading slash from remote path
+	blobName := strings.TrimPrefix(remotePath, "/")
+
+	// Use block blob upload for large files (>256MB), simple upload for smaller
+	const blockUploadThreshold = 256 * 1024 * 1024 // 256 MB
+
+	if fileSize > blockUploadThreshold {
+		return a.uploadBlocks(ctx, file, blobName, fileSize, progress)
+	}
+
+	return a.uploadSimple(ctx, file, blobName, fileSize, progress)
+}
+
+// uploadSimple uploads a file using simple upload (single request)
+func (a *AzureBackend) uploadSimple(ctx context.Context, file *os.File, blobName string, fileSize int64, progress ProgressCallback) error {
+	blockBlobClient := a.client.ServiceClient().NewContainerClient(a.containerName).NewBlockBlobClient(blobName)
+
+	// Wrap reader with progress tracking
+	reader := NewProgressReader(file, fileSize, progress)
+
+	// Calculate MD5 hash for integrity
+	hash := sha256.New()
+	teeReader := io.TeeReader(reader, hash)
+
+	_, err := blockBlobClient.UploadStream(ctx, teeReader, &blockblob.UploadStreamOptions{
+		BlockSize: 4 * 1024 * 1024, // 4MB blocks
+	})
+	if err != nil {
+		return fmt.Errorf("failed to upload blob: %w", err)
+	}
+
+	// Store checksum as metadata
+	checksum := hex.EncodeToString(hash.Sum(nil))
+	metadata := map[string]*string{
+		"sha256": &checksum,
+	}
+
+	_, err = blockBlobClient.SetMetadata(ctx, metadata, nil)
+	if err != nil {
+		// Non-fatal: upload succeeded but metadata failed
+		fmt.Fprintf(os.Stderr, "Warning: failed to set blob metadata: %v\n", err)
+	}
+
+	return nil
+}
+
+// uploadBlocks uploads a file using block blob staging (for large files)
+func (a *AzureBackend) uploadBlocks(ctx context.Context, file *os.File, blobName string, fileSize int64, progress ProgressCallback) error {
+	blockBlobClient := a.client.ServiceClient().NewContainerClient(a.containerName).NewBlockBlobClient(blobName)
+
+	const blockSize = 100 * 1024 * 1024 // 100MB per block
+	numBlocks := (fileSize + blockSize - 1) / blockSize
+
+	blockIDs := make([]string, 0, numBlocks)
+	hash := sha256.New()
+	var totalUploaded int64
+
+	for i := int64(0); i < numBlocks; i++ {
+		blockID := base64.StdEncoding.EncodeToString([]byte(fmt.Sprintf("block-%08d", i)))
+		blockIDs = append(blockIDs, blockID)
+
+		// Calculate block size
+		currentBlockSize := blockSize
+		if i == numBlocks-1 {
+			currentBlockSize = int(fileSize - i*blockSize)
+		}
+
+		// Read block
+		blockData := make([]byte, currentBlockSize)
+		n, err := io.ReadFull(file, blockData)
+		if err != nil && err != io.ErrUnexpectedEOF {
+			return fmt.Errorf("failed to read block %d: %w", i, err)
+		}
+		blockData = blockData[:n]
+
+		// Update hash
+		hash.Write(blockData)
+
+		// Upload block
+		reader := bytes.NewReader(blockData)
+		_, err = blockBlobClient.StageBlock(ctx, blockID, streaming.NopCloser(reader), nil)
+		if err != nil {
+			return fmt.Errorf("failed to stage block %d: %w", i, err)
+		}
+
+		// Update progress
+		totalUploaded += int64(n)
+		if progress != nil {
+			progress(totalUploaded, fileSize)
+		}
+	}
+
+	// Commit all blocks
+	_, err := blockBlobClient.CommitBlockList(ctx, blockIDs, nil)
+	if err != nil {
+		return fmt.Errorf("failed to commit block list: %w", err)
+	}
+
+	// Store checksum as metadata
+	checksum := hex.EncodeToString(hash.Sum(nil))
+	metadata := map[string]*string{
+		"sha256": &checksum,
+	}
+
+	_, err = blockBlobClient.SetMetadata(ctx, metadata, nil)
+	if err != nil {
+		// Non-fatal
+		fmt.Fprintf(os.Stderr, "Warning: failed to set blob metadata: %v\n", err)
+	}
+
+	return nil
+}
+
+// Download downloads a file from Azure Blob Storage
+func (a *AzureBackend) Download(ctx context.Context, remotePath, localPath string, progress ProgressCallback) error {
+	blobName := strings.TrimPrefix(remotePath, "/")
+	blockBlobClient := a.client.ServiceClient().NewContainerClient(a.containerName).NewBlockBlobClient(blobName)
+
+	// Get blob properties to know size
+	props, err := blockBlobClient.GetProperties(ctx, nil)
+	if err != nil {
+		return fmt.Errorf("failed to get blob properties: %w", err)
+	}
+
+	fileSize := *props.ContentLength
+
+	// Download blob
+	resp, err := blockBlobClient.DownloadStream(ctx, nil)
+	if err != nil {
+		return fmt.Errorf("failed to download blob: %w", err)
+	}
+	defer resp.Body.Close()
+
+	// Create local file
+	file, err := os.Create(localPath)
+	if err != nil {
+		return fmt.Errorf("failed to create file: %w", err)
+	}
+	defer file.Close()
+
+	// Wrap reader with progress tracking
+	reader := NewProgressReader(resp.Body, fileSize, progress)
+
+	// Copy with progress
+	_, err = io.Copy(file, reader)
+	if err != nil {
+		return fmt.Errorf("failed to write file: %w", err)
+	}
+
+	return nil
+}
+
+// Delete deletes a file from Azure Blob Storage
+func (a *AzureBackend) Delete(ctx context.Context, remotePath string) error {
+	blobName := strings.TrimPrefix(remotePath, "/")
+	blockBlobClient := a.client.ServiceClient().NewContainerClient(a.containerName).NewBlockBlobClient(blobName)
+
+	_, err := blockBlobClient.Delete(ctx, nil)
+	if err != nil {
+		return fmt.Errorf("failed to delete blob: %w", err)
+	}
+
+	return nil
+}
+
+// List lists files in Azure Blob Storage with a given prefix
+func (a *AzureBackend) List(ctx context.Context, prefix string) ([]BackupInfo, error) {
+	prefix = strings.TrimPrefix(prefix, "/")
+	containerClient := a.client.ServiceClient().NewContainerClient(a.containerName)
+
+	pager := containerClient.NewListBlobsFlatPager(&container.ListBlobsFlatOptions{
+		Prefix: &prefix,
+	})
+
+	var files []BackupInfo
+
+	for pager.More() {
+		page, err := pager.NextPage(ctx)
+		if err != nil {
+			return nil, fmt.Errorf("failed to list blobs: %w", err)
+		}
+
+		for _, blob := range page.Segment.BlobItems {
+			if blob.Name == nil || blob.Properties == nil {
+				continue
+			}
+
+			file := BackupInfo{
+				Key:          *blob.Name,
+				Name:         filepath.Base(*blob.Name),
+				Size:         *blob.Properties.ContentLength,
+				LastModified: *blob.Properties.LastModified,
+			}
+
+			// Try to get SHA256 from metadata
+			if blob.Metadata != nil {
+				if sha256Val, ok := blob.Metadata["sha256"]; ok && sha256Val != nil {
+					file.ETag = *sha256Val
+				}
+			}
+
+			files = append(files, file)
+		}
+	}
+
+	return files, nil
+}
+
+// Exists checks if a file exists in Azure Blob Storage
+func (a *AzureBackend) Exists(ctx context.Context, remotePath string) (bool, error) {
+	blobName := strings.TrimPrefix(remotePath, "/")
+	blockBlobClient := a.client.ServiceClient().NewContainerClient(a.containerName).NewBlockBlobClient(blobName)
+
+	_, err := blockBlobClient.GetProperties(ctx, nil)
+	if err != nil {
+		var respErr *azcore.ResponseError
+		if respErr != nil && respErr.StatusCode == 404 {
+			return false, nil
+		}
+		// Check if error message contains "not found"
+		if strings.Contains(err.Error(), "BlobNotFound") || strings.Contains(err.Error(), "404") {
+			return false, nil
+		}
+		return false, fmt.Errorf("failed to check blob existence: %w", err)
+	}
+
+	return true, nil
+}
+
+// GetSize returns the size of a file in Azure Blob Storage
+func (a *AzureBackend) GetSize(ctx context.Context, remotePath string) (int64, error) {
+	blobName := strings.TrimPrefix(remotePath, "/")
+	blockBlobClient := a.client.ServiceClient().NewContainerClient(a.containerName).NewBlockBlobClient(blobName)
+
+	props, err := blockBlobClient.GetProperties(ctx, nil)
+	if err != nil {
+		return 0, fmt.Errorf("failed to get blob properties: %w", err)
+	}
+
+	return *props.ContentLength, nil
+}

internal/cloud/gcs.go

@@ -0,0 +1,275 @@
+package cloud
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"cloud.google.com/go/storage"
+	"google.golang.org/api/iterator"
+	"google.golang.org/api/option"
+)
+
+// GCSBackend implements the Backend interface for Google Cloud Storage
+type GCSBackend struct {
+	client     *storage.Client
+	bucketName string
+	config     *Config
+}
+
+// NewGCSBackend creates a new Google Cloud Storage backend
+func NewGCSBackend(cfg *Config) (*GCSBackend, error) {
+	if cfg.Bucket == "" {
+		return nil, fmt.Errorf("bucket name is required for GCS backend")
+	}
+
+	var client *storage.Client
+	var err error
+	ctx := context.Background()
+
+	// Support for fake-gcs-server emulator (uses endpoint override)
+	if cfg.Endpoint != "" {
+		// For fake-gcs-server and custom endpoints
+		client, err = storage.NewClient(ctx, option.WithEndpoint(cfg.Endpoint), option.WithoutAuthentication())
+		if err != nil {
+			return nil, fmt.Errorf("failed to create GCS client: %w", err)
+		}
+	} else {
+		// Production GCS using Application Default Credentials or service account
+		if cfg.AccessKey != "" {
+			// Use service account JSON key file
+			client, err = storage.NewClient(ctx, option.WithCredentialsFile(cfg.AccessKey))
+			if err != nil {
+				return nil, fmt.Errorf("failed to create GCS client with credentials file: %w", err)
+			}
+		} else {
+			// Use default credentials (ADC, environment variables, etc.)
+			client, err = storage.NewClient(ctx)
+			if err != nil {
+				return nil, fmt.Errorf("failed to create GCS client: %w", err)
+			}
+		}
+	}
+
+	backend := &GCSBackend{
+		client:     client,
+		bucketName: cfg.Bucket,
+		config:     cfg,
+	}
+
+	// Create bucket if it doesn't exist
+	// Note: Bucket creation should be done manually or via gcloud CLI
+	if false { // Disabled: cfg.CreateBucket not in Config
+		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+		defer cancel()
+
+		bucket := client.Bucket(cfg.Bucket)
+		_, err = bucket.Attrs(ctx)
+		if err == storage.ErrBucketNotExist {
+			// Create bucket with default settings
+			if err := bucket.Create(ctx, cfg.AccessKey, nil); err != nil {
+				return nil, fmt.Errorf("failed to create bucket: %w", err)
+			}
+		} else if err != nil {
+			return nil, fmt.Errorf("failed to check bucket: %w", err)
+		}
+	}
+
+	return backend, nil
+}
+
+// Name returns the backend name
+func (g *GCSBackend) Name() string {
+	return "gcs"
+}
+
+// Upload uploads a file to Google Cloud Storage
+func (g *GCSBackend) Upload(ctx context.Context, localPath, remotePath string, progress ProgressCallback) error {
+	file, err := os.Open(localPath)
+	if err != nil {
+		return fmt.Errorf("failed to open file: %w", err)
+	}
+	defer file.Close()
+
+	fileInfo, err := file.Stat()
+	if err != nil {
+		return fmt.Errorf("failed to stat file: %w", err)
+	}
+	fileSize := fileInfo.Size()
+
+	// Remove leading slash from remote path
+	objectName := strings.TrimPrefix(remotePath, "/")
+
+	bucket := g.client.Bucket(g.bucketName)
+	object := bucket.Object(objectName)
+
+	// Create writer with automatic chunking for large files
+	writer := object.NewWriter(ctx)
+	writer.ChunkSize = 16 * 1024 * 1024 // 16MB chunks for streaming
+
+	// Wrap reader with progress tracking and hash calculation
+	hash := sha256.New()
+	reader := NewProgressReader(io.TeeReader(file, hash), fileSize, progress)
+
+	// Upload with progress tracking
+	_, err = io.Copy(writer, reader)
+	if err != nil {
+		writer.Close()
+		return fmt.Errorf("failed to upload object: %w", err)
+	}
+
+	// Close writer (finalizes upload)
+	if err := writer.Close(); err != nil {
+		return fmt.Errorf("failed to finalize upload: %w", err)
+	}
+
+	// Store checksum as metadata
+	checksum := hex.EncodeToString(hash.Sum(nil))
+	_, err = object.Update(ctx, storage.ObjectAttrsToUpdate{
+		Metadata: map[string]string{
+			"sha256": checksum,
+		},
+	})
+	if err != nil {
+		// Non-fatal: upload succeeded but metadata failed
+		fmt.Fprintf(os.Stderr, "Warning: failed to set object metadata: %v\n", err)
+	}
+
+	return nil
+}
+
+// Download downloads a file from Google Cloud Storage
+func (g *GCSBackend) Download(ctx context.Context, remotePath, localPath string, progress ProgressCallback) error {
+	objectName := strings.TrimPrefix(remotePath, "/")
+
+	bucket := g.client.Bucket(g.bucketName)
+	object := bucket.Object(objectName)
+
+	// Get object attributes to know size
+	attrs, err := object.Attrs(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to get object attributes: %w", err)
+	}
+
+	fileSize := attrs.Size
+
+	// Create reader
+	reader, err := object.NewReader(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to download object: %w", err)
+	}
+	defer reader.Close()
+
+	// Create local file
+	file, err := os.Create(localPath)
+	if err != nil {
+		return fmt.Errorf("failed to create file: %w", err)
+	}
+	defer file.Close()
+
+	// Wrap reader with progress tracking
+	progressReader := NewProgressReader(reader, fileSize, progress)
+
+	// Copy with progress
+	_, err = io.Copy(file, progressReader)
+	if err != nil {
+		return fmt.Errorf("failed to write file: %w", err)
+	}
+
+	return nil
+}
+
+// Delete deletes a file from Google Cloud Storage
+func (g *GCSBackend) Delete(ctx context.Context, remotePath string) error {
+	objectName := strings.TrimPrefix(remotePath, "/")
+
+	bucket := g.client.Bucket(g.bucketName)
+	object := bucket.Object(objectName)
+
+	if err := object.Delete(ctx); err != nil {
+		return fmt.Errorf("failed to delete object: %w", err)
+	}
+
+	return nil
+}
+
+// List lists files in Google Cloud Storage with a given prefix
+func (g *GCSBackend) List(ctx context.Context, prefix string) ([]BackupInfo, error) {
+	prefix = strings.TrimPrefix(prefix, "/")
+
+	bucket := g.client.Bucket(g.bucketName)
+	query := &storage.Query{
+		Prefix: prefix,
+	}
+
+	it := bucket.Objects(ctx, query)
+
+	var files []BackupInfo
+
+	for {
+		attrs, err := it.Next()
+		if err == iterator.Done {
+			break
+		}
+		if err != nil {
+			return nil, fmt.Errorf("failed to list objects: %w", err)
+		}
+
+		file := BackupInfo{
+			Key:          attrs.Name,
+			Name:         filepath.Base(attrs.Name),
+			Size:         attrs.Size,
+			LastModified: attrs.Updated,
+		}
+
+		// Try to get SHA256 from metadata
+		if attrs.Metadata != nil {
+			if sha256Val, ok := attrs.Metadata["sha256"]; ok {
+				file.ETag = sha256Val
+			}
+		}
+
+		files = append(files, file)
+	}
+
+	return files, nil
+}
+
+// Exists checks if a file exists in Google Cloud Storage
+func (g *GCSBackend) Exists(ctx context.Context, remotePath string) (bool, error) {
+	objectName := strings.TrimPrefix(remotePath, "/")
+
+	bucket := g.client.Bucket(g.bucketName)
+	object := bucket.Object(objectName)
+
+	_, err := object.Attrs(ctx)
+	if err == storage.ErrObjectNotExist {
+		return false, nil
+	}
+	if err != nil {
+		return false, fmt.Errorf("failed to check object existence: %w", err)
+	}
+
+	return true, nil
+}
+
+// GetSize returns the size of a file in Google Cloud Storage
+func (g *GCSBackend) GetSize(ctx context.Context, remotePath string) (int64, error) {
+	objectName := strings.TrimPrefix(remotePath, "/")
+
+	bucket := g.client.Bucket(g.bucketName)
+	object := bucket.Object(objectName)
+
+	attrs, err := object.Attrs(ctx)
+	if err != nil {
+		return 0, fmt.Errorf("failed to get object attributes: %w", err)
+	}
+
+	return attrs.Size, nil
+}

internal/cloud/interface.go

@@ -79,8 +79,12 @@ func NewBackend(cfg *Config) (Backend, error) {
 			return nil, fmt.Errorf("endpoint required for Backblaze B2")
 		}
 		return NewS3Backend(cfg)
+	case "azure", "azblob":
+		return NewAzureBackend(cfg)
+	case "gs", "gcs", "google":
+		return NewGCSBackend(cfg)
 	default:
-		return nil, fmt.Errorf("unsupported cloud provider: %s (supported: s3, minio, b2)", cfg.Provider)
+		return nil, fmt.Errorf("unsupported cloud provider: %s (supported: s3, minio, b2, azure, gcs)", cfg.Provider)
 	}
 }
 

internal/config/config.go

@@ -88,13 +88,13 @@ type Config struct {
 
 	// Cloud storage options (v2.0)
 	CloudEnabled    bool   // Enable cloud storage integration
-	CloudProvider   string // "s3", "minio", "b2"
+	CloudProvider   string // "s3", "minio", "b2", "azure", "gcs"
-	CloudBucket     string // Bucket name
+	CloudBucket     string // Bucket/container name
-	CloudRegion     string // Region (for S3)
+	CloudRegion     string // Region (for S3, GCS)
-	CloudEndpoint   string // Custom endpoint (for MinIO, B2)
+	CloudEndpoint   string // Custom endpoint (for MinIO, B2, Azurite, fake-gcs-server)
-	CloudAccessKey  string // Access key
+	CloudAccessKey  string // Access key / Account name (Azure) / Service account file (GCS)
-	CloudSecretKey  string // Secret key
+	CloudSecretKey  string // Secret key / Account key (Azure)
-	CloudPrefix     string // Key prefix
+	CloudPrefix     string // Key/object prefix
 	CloudAutoUpload bool   // Automatically upload after backup
 }
 

scripts/test_azure_storage.sh

@@ -0,0 +1,382 @@
+#!/bin/bash
+
+# Azure Blob Storage (Azurite) Testing Script for dbbackup
+# Tests backup, restore, verify, and cleanup with Azure emulator
+
+set -e
+
+# Colors for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+NC='\033[0m' # No Color
+
+# Test configuration
+AZURITE_ENDPOINT="http://localhost:10000"
+CONTAINER_NAME="test-backups"
+ACCOUNT_NAME="devstoreaccount1"
+ACCOUNT_KEY="Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw=="
+
+# Database connection details (from docker-compose)
+POSTGRES_HOST="localhost"
+POSTGRES_PORT="5434"
+POSTGRES_USER="testuser"
+POSTGRES_PASS="testpass"
+POSTGRES_DB="testdb"
+
+MYSQL_HOST="localhost"
+MYSQL_PORT="3308"
+MYSQL_USER="testuser"
+MYSQL_PASS="testpass"
+MYSQL_DB="testdb"
+
+# Test counters
+TESTS_PASSED=0
+TESTS_FAILED=0
+
+# Functions
+print_header() {
+    echo -e "\n${BLUE}=== $1 ===${NC}\n"
+}
+
+print_success() {
+    echo -e "${GREEN}✓ $1${NC}"
+    ((TESTS_PASSED++))
+}
+
+print_error() {
+    echo -e "${RED}✗ $1${NC}"
+    ((TESTS_FAILED++))
+}
+
+print_info() {
+    echo -e "${YELLOW}ℹ $1${NC}"
+}
+
+wait_for_azurite() {
+    print_info "Waiting for Azurite to be ready..."
+    for i in {1..30}; do
+        if curl -f -s "${AZURITE_ENDPOINT}/devstoreaccount1?restype=account&comp=properties" > /dev/null 2>&1; then
+            print_success "Azurite is ready"
+            return 0
+        fi
+        sleep 1
+    done
+    print_error "Azurite failed to start"
+    return 1
+}
+
+# Build dbbackup if needed
+build_dbbackup() {
+    print_header "Building dbbackup"
+    if [ ! -f "./dbbackup" ]; then
+        go build -o dbbackup .
+        print_success "Built dbbackup binary"
+    else
+        print_info "Using existing dbbackup binary"
+    fi
+}
+
+# Start services
+start_services() {
+    print_header "Starting Azurite and Database Services"
+    docker-compose -f docker-compose.azurite.yml up -d
+    
+    # Wait for services
+    sleep 5
+    wait_for_azurite
+    
+    print_info "Waiting for PostgreSQL..."
+    sleep 3
+    
+    print_info "Waiting for MySQL..."
+    sleep 3
+    
+    print_success "All services started"
+}
+
+# Stop services
+stop_services() {
+    print_header "Stopping Services"
+    docker-compose -f docker-compose.azurite.yml down
+    print_success "Services stopped"
+}
+
+# Create test data in databases
+create_test_data() {
+    print_header "Creating Test Data"
+    
+    # PostgreSQL
+    PGPASSWORD=$POSTGRES_PASS psql -h $POSTGRES_HOST -p $POSTGRES_PORT -U $POSTGRES_USER -d $POSTGRES_DB <<EOF
+DROP TABLE IF EXISTS test_table;
+CREATE TABLE test_table (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(100),
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+INSERT INTO test_table (name) VALUES ('Azure Test 1'), ('Azure Test 2'), ('Azure Test 3');
+EOF
+    print_success "Created PostgreSQL test data"
+    
+    # MySQL
+    mysql -h $MYSQL_HOST -P $MYSQL_PORT -u $MYSQL_USER -p$MYSQL_PASS $MYSQL_DB <<EOF
+DROP TABLE IF EXISTS test_table;
+CREATE TABLE test_table (
+    id INT AUTO_INCREMENT PRIMARY KEY,
+    name VARCHAR(100),
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+INSERT INTO test_table (name) VALUES ('Azure Test 1'), ('Azure Test 2'), ('Azure Test 3');
+EOF
+    print_success "Created MySQL test data"
+}
+
+# Test 1: PostgreSQL backup to Azure
+test_postgres_backup() {
+    print_header "Test 1: PostgreSQL Backup to Azure"
+    
+    ./dbbackup backup postgres \
+        --host $POSTGRES_HOST \
+        --port $POSTGRES_PORT \
+        --user $POSTGRES_USER \
+        --password $POSTGRES_PASS \
+        --database $POSTGRES_DB \
+        --output ./backups/pg_azure_test.sql \
+        --cloud "azure://$CONTAINER_NAME/postgres/backup1.sql?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY"
+    
+    if [ $? -eq 0 ]; then
+        print_success "PostgreSQL backup uploaded to Azure"
+    else
+        print_error "PostgreSQL backup failed"
+        return 1
+    fi
+}
+
+# Test 2: MySQL backup to Azure
+test_mysql_backup() {
+    print_header "Test 2: MySQL Backup to Azure"
+    
+    ./dbbackup backup mysql \
+        --host $MYSQL_HOST \
+        --port $MYSQL_PORT \
+        --user $MYSQL_USER \
+        --password $MYSQL_PASS \
+        --database $MYSQL_DB \
+        --output ./backups/mysql_azure_test.sql \
+        --cloud "azure://$CONTAINER_NAME/mysql/backup1.sql?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY"
+    
+    if [ $? -eq 0 ]; then
+        print_success "MySQL backup uploaded to Azure"
+    else
+        print_error "MySQL backup failed"
+        return 1
+    fi
+}
+
+# Test 3: List backups in Azure
+test_list_backups() {
+    print_header "Test 3: List Azure Backups"
+    
+    ./dbbackup cloud list "azure://$CONTAINER_NAME/postgres/?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY"
+    
+    if [ $? -eq 0 ]; then
+        print_success "Listed Azure backups"
+    else
+        print_error "Failed to list backups"
+        return 1
+    fi
+}
+
+# Test 4: Verify backup in Azure
+test_verify_backup() {
+    print_header "Test 4: Verify Azure Backup"
+    
+    ./dbbackup verify "azure://$CONTAINER_NAME/postgres/backup1.sql?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY"
+    
+    if [ $? -eq 0 ]; then
+        print_success "Backup verification successful"
+    else
+        print_error "Backup verification failed"
+        return 1
+    fi
+}
+
+# Test 5: Restore from Azure
+test_restore_from_azure() {
+    print_header "Test 5: Restore from Azure"
+    
+    # Drop and recreate database
+    PGPASSWORD=$POSTGRES_PASS psql -h $POSTGRES_HOST -p $POSTGRES_PORT -U $POSTGRES_USER -d postgres <<EOF
+DROP DATABASE IF EXISTS testdb_restored;
+CREATE DATABASE testdb_restored;
+EOF
+    
+    ./dbbackup restore postgres \
+        --source "azure://$CONTAINER_NAME/postgres/backup1.sql?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY" \
+        --host $POSTGRES_HOST \
+        --port $POSTGRES_PORT \
+        --user $POSTGRES_USER \
+        --password $POSTGRES_PASS \
+        --database testdb_restored
+    
+    if [ $? -eq 0 ]; then
+        print_success "Restored from Azure backup"
+        
+        # Verify restored data
+        COUNT=$(PGPASSWORD=$POSTGRES_PASS psql -h $POSTGRES_HOST -p $POSTGRES_PORT -U $POSTGRES_USER -d testdb_restored -t -c "SELECT COUNT(*) FROM test_table;")
+        if [ "$COUNT" -eq 3 ]; then
+            print_success "Restored data verified (3 rows)"
+        else
+            print_error "Restored data incorrect (expected 3 rows, got $COUNT)"
+        fi
+    else
+        print_error "Restore from Azure failed"
+        return 1
+    fi
+}
+
+# Test 6: Large file upload (block blob)
+test_large_file_upload() {
+    print_header "Test 6: Large File Upload (Block Blob)"
+    
+    # Create a large test file (300MB)
+    print_info "Creating 300MB test file..."
+    dd if=/dev/urandom of=./backups/large_test.dat bs=1M count=300 2>/dev/null
+    
+    print_info "Uploading large file to Azure..."
+    ./dbbackup cloud upload \
+        ./backups/large_test.dat \
+        "azure://$CONTAINER_NAME/large/large_test.dat?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY"
+    
+    if [ $? -eq 0 ]; then
+        print_success "Large file uploaded successfully (block blob)"
+        
+        # Verify file exists and has correct size
+        print_info "Downloading large file..."
+        ./dbbackup cloud download \
+            "azure://$CONTAINER_NAME/large/large_test.dat?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY" \
+            ./backups/large_test_downloaded.dat
+        
+        if [ $? -eq 0 ]; then
+            ORIGINAL_SIZE=$(stat -f%z ./backups/large_test.dat 2>/dev/null || stat -c%s ./backups/large_test.dat)
+            DOWNLOADED_SIZE=$(stat -f%z ./backups/large_test_downloaded.dat 2>/dev/null || stat -c%s ./backups/large_test_downloaded.dat)
+            
+            if [ "$ORIGINAL_SIZE" -eq "$DOWNLOADED_SIZE" ]; then
+                print_success "Downloaded file size matches original ($ORIGINAL_SIZE bytes)"
+            else
+                print_error "File size mismatch (original: $ORIGINAL_SIZE, downloaded: $DOWNLOADED_SIZE)"
+            fi
+        else
+            print_error "Large file download failed"
+        fi
+        
+        # Cleanup
+        rm -f ./backups/large_test.dat ./backups/large_test_downloaded.dat
+    else
+        print_error "Large file upload failed"
+        return 1
+    fi
+}
+
+# Test 7: Delete from Azure
+test_delete_backup() {
+    print_header "Test 7: Delete Backup from Azure"
+    
+    ./dbbackup cloud delete "azure://$CONTAINER_NAME/mysql/backup1.sql?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY"
+    
+    if [ $? -eq 0 ]; then
+        print_success "Deleted backup from Azure"
+        
+        # Verify deletion
+        if ! ./dbbackup cloud list "azure://$CONTAINER_NAME/mysql/?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY" | grep -q "backup1.sql"; then
+            print_success "Verified backup was deleted"
+        else
+            print_error "Backup still exists after deletion"
+        fi
+    else
+        print_error "Failed to delete backup"
+        return 1
+    fi
+}
+
+# Test 8: Cleanup old backups
+test_cleanup() {
+    print_header "Test 8: Cleanup Old Backups"
+    
+    # Create multiple backups with different timestamps
+    for i in {1..5}; do
+        ./dbbackup backup postgres \
+            --host $POSTGRES_HOST \
+            --port $POSTGRES_PORT \
+            --user $POSTGRES_USER \
+            --password $POSTGRES_PASS \
+            --database $POSTGRES_DB \
+            --output "./backups/pg_cleanup_$i.sql" \
+            --cloud "azure://$CONTAINER_NAME/cleanup/backup_$i.sql?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY"
+        sleep 1
+    done
+    
+    print_success "Created 5 test backups"
+    
+    # Cleanup, keeping only 2
+    ./dbbackup cleanup "azure://$CONTAINER_NAME/cleanup/?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY" --keep 2
+    
+    if [ $? -eq 0 ]; then
+        print_success "Cleanup completed"
+        
+        # Count remaining backups
+        COUNT=$(./dbbackup cloud list "azure://$CONTAINER_NAME/cleanup/?endpoint=$AZURITE_ENDPOINT&account=$ACCOUNT_NAME&key=$ACCOUNT_KEY" | grep -c "backup_")
+        if [ "$COUNT" -le 2 ]; then
+            print_success "Verified cleanup (kept 2 backups)"
+        else
+            print_error "Cleanup failed (expected 2 backups, found $COUNT)"
+        fi
+    else
+        print_error "Cleanup failed"
+        return 1
+    fi
+}
+
+# Main test execution
+main() {
+    print_header "Azure Blob Storage (Azurite) Integration Tests"
+    
+    # Setup
+    build_dbbackup
+    start_services
+    create_test_data
+    
+    # Run tests
+    test_postgres_backup
+    test_mysql_backup
+    test_list_backups
+    test_verify_backup
+    test_restore_from_azure
+    test_large_file_upload
+    test_delete_backup
+    test_cleanup
+    
+    # Cleanup
+    print_header "Cleanup"
+    rm -rf ./backups
+    
+    # Summary
+    print_header "Test Summary"
+    echo -e "${GREEN}Passed: $TESTS_PASSED${NC}"
+    echo -e "${RED}Failed: $TESTS_FAILED${NC}"
+    
+    if [ $TESTS_FAILED -eq 0 ]; then
+        print_success "All tests passed!"
+        stop_services
+        exit 0
+    else
+        print_error "Some tests failed"
+        print_info "Leaving services running for debugging"
+        print_info "Run 'docker-compose -f docker-compose.azurite.yml down' to stop services"
+        exit 1
+    fi
+}
+
+# Run main
+main

scripts/test_gcs_storage.sh

@@ -0,0 +1,390 @@
+#!/bin/bash
+
+# Google Cloud Storage (fake-gcs-server) Testing Script for dbbackup
+# Tests backup, restore, verify, and cleanup with GCS emulator
+
+set -e
+
+# Colors for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+NC='\033[0m' # No Color
+
+# Test configuration
+GCS_ENDPOINT="http://localhost:4443/storage/v1"
+BUCKET_NAME="test-backups"
+PROJECT_ID="test-project"
+
+# Database connection details (from docker-compose)
+POSTGRES_HOST="localhost"
+POSTGRES_PORT="5435"
+POSTGRES_USER="testuser"
+POSTGRES_PASS="testpass"
+POSTGRES_DB="testdb"
+
+MYSQL_HOST="localhost"
+MYSQL_PORT="3309"
+MYSQL_USER="testuser"
+MYSQL_PASS="testpass"
+MYSQL_DB="testdb"
+
+# Test counters
+TESTS_PASSED=0
+TESTS_FAILED=0
+
+# Functions
+print_header() {
+    echo -e "\n${BLUE}=== $1 ===${NC}\n"
+}
+
+print_success() {
+    echo -e "${GREEN}✓ $1${NC}"
+    ((TESTS_PASSED++))
+}
+
+print_error() {
+    echo -e "${RED}✗ $1${NC}"
+    ((TESTS_FAILED++))
+}
+
+print_info() {
+    echo -e "${YELLOW}ℹ $1${NC}"
+}
+
+wait_for_gcs() {
+    print_info "Waiting for fake-gcs-server to be ready..."
+    for i in {1..30}; do
+        if curl -f -s "$GCS_ENDPOINT/b" > /dev/null 2>&1; then
+            print_success "fake-gcs-server is ready"
+            return 0
+        fi
+        sleep 1
+    done
+    print_error "fake-gcs-server failed to start"
+    return 1
+}
+
+create_test_bucket() {
+    print_info "Creating test bucket..."
+    curl -X POST "$GCS_ENDPOINT/b?project=$PROJECT_ID" \
+        -H "Content-Type: application/json" \
+        -d "{\"name\": \"$BUCKET_NAME\"}" > /dev/null 2>&1 || true
+    print_success "Test bucket created"
+}
+
+# Build dbbackup if needed
+build_dbbackup() {
+    print_header "Building dbbackup"
+    if [ ! -f "./dbbackup" ]; then
+        go build -o dbbackup .
+        print_success "Built dbbackup binary"
+    else
+        print_info "Using existing dbbackup binary"
+    fi
+}
+
+# Start services
+start_services() {
+    print_header "Starting GCS Emulator and Database Services"
+    docker-compose -f docker-compose.gcs.yml up -d
+    
+    # Wait for services
+    sleep 5
+    wait_for_gcs
+    create_test_bucket
+    
+    print_info "Waiting for PostgreSQL..."
+    sleep 3
+    
+    print_info "Waiting for MySQL..."
+    sleep 3
+    
+    print_success "All services started"
+}
+
+# Stop services
+stop_services() {
+    print_header "Stopping Services"
+    docker-compose -f docker-compose.gcs.yml down
+    print_success "Services stopped"
+}
+
+# Create test data in databases
+create_test_data() {
+    print_header "Creating Test Data"
+    
+    # PostgreSQL
+    PGPASSWORD=$POSTGRES_PASS psql -h $POSTGRES_HOST -p $POSTGRES_PORT -U $POSTGRES_USER -d $POSTGRES_DB <<EOF
+DROP TABLE IF EXISTS test_table;
+CREATE TABLE test_table (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(100),
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+INSERT INTO test_table (name) VALUES ('GCS Test 1'), ('GCS Test 2'), ('GCS Test 3');
+EOF
+    print_success "Created PostgreSQL test data"
+    
+    # MySQL
+    mysql -h $MYSQL_HOST -P $MYSQL_PORT -u $MYSQL_USER -p$MYSQL_PASS $MYSQL_DB <<EOF
+DROP TABLE IF EXISTS test_table;
+CREATE TABLE test_table (
+    id INT AUTO_INCREMENT PRIMARY KEY,
+    name VARCHAR(100),
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+INSERT INTO test_table (name) VALUES ('GCS Test 1'), ('GCS Test 2'), ('GCS Test 3');
+EOF
+    print_success "Created MySQL test data"
+}
+
+# Test 1: PostgreSQL backup to GCS
+test_postgres_backup() {
+    print_header "Test 1: PostgreSQL Backup to GCS"
+    
+    ./dbbackup backup postgres \
+        --host $POSTGRES_HOST \
+        --port $POSTGRES_PORT \
+        --user $POSTGRES_USER \
+        --password $POSTGRES_PASS \
+        --database $POSTGRES_DB \
+        --output ./backups/pg_gcs_test.sql \
+        --cloud "gs://$BUCKET_NAME/postgres/backup1.sql?endpoint=$GCS_ENDPOINT"
+    
+    if [ $? -eq 0 ]; then
+        print_success "PostgreSQL backup uploaded to GCS"
+    else
+        print_error "PostgreSQL backup failed"
+        return 1
+    fi
+}
+
+# Test 2: MySQL backup to GCS
+test_mysql_backup() {
+    print_header "Test 2: MySQL Backup to GCS"
+    
+    ./dbbackup backup mysql \
+        --host $MYSQL_HOST \
+        --port $MYSQL_PORT \
+        --user $MYSQL_USER \
+        --password $MYSQL_PASS \
+        --database $MYSQL_DB \
+        --output ./backups/mysql_gcs_test.sql \
+        --cloud "gs://$BUCKET_NAME/mysql/backup1.sql?endpoint=$GCS_ENDPOINT"
+    
+    if [ $? -eq 0 ]; then
+        print_success "MySQL backup uploaded to GCS"
+    else
+        print_error "MySQL backup failed"
+        return 1
+    fi
+}
+
+# Test 3: List backups in GCS
+test_list_backups() {
+    print_header "Test 3: List GCS Backups"
+    
+    ./dbbackup cloud list "gs://$BUCKET_NAME/postgres/?endpoint=$GCS_ENDPOINT"
+    
+    if [ $? -eq 0 ]; then
+        print_success "Listed GCS backups"
+    else
+        print_error "Failed to list backups"
+        return 1
+    fi
+}
+
+# Test 4: Verify backup in GCS
+test_verify_backup() {
+    print_header "Test 4: Verify GCS Backup"
+    
+    ./dbbackup verify "gs://$BUCKET_NAME/postgres/backup1.sql?endpoint=$GCS_ENDPOINT"
+    
+    if [ $? -eq 0 ]; then
+        print_success "Backup verification successful"
+    else
+        print_error "Backup verification failed"
+        return 1
+    fi
+}
+
+# Test 5: Restore from GCS
+test_restore_from_gcs() {
+    print_header "Test 5: Restore from GCS"
+    
+    # Drop and recreate database
+    PGPASSWORD=$POSTGRES_PASS psql -h $POSTGRES_HOST -p $POSTGRES_PORT -U $POSTGRES_USER -d postgres <<EOF
+DROP DATABASE IF EXISTS testdb_restored;
+CREATE DATABASE testdb_restored;
+EOF
+    
+    ./dbbackup restore postgres \
+        --source "gs://$BUCKET_NAME/postgres/backup1.sql?endpoint=$GCS_ENDPOINT" \
+        --host $POSTGRES_HOST \
+        --port $POSTGRES_PORT \
+        --user $POSTGRES_USER \
+        --password $POSTGRES_PASS \
+        --database testdb_restored
+    
+    if [ $? -eq 0 ]; then
+        print_success "Restored from GCS backup"
+        
+        # Verify restored data
+        COUNT=$(PGPASSWORD=$POSTGRES_PASS psql -h $POSTGRES_HOST -p $POSTGRES_PORT -U $POSTGRES_USER -d testdb_restored -t -c "SELECT COUNT(*) FROM test_table;")
+        if [ "$COUNT" -eq 3 ]; then
+            print_success "Restored data verified (3 rows)"
+        else
+            print_error "Restored data incorrect (expected 3 rows, got $COUNT)"
+        fi
+    else
+        print_error "Restore from GCS failed"
+        return 1
+    fi
+}
+
+# Test 6: Large file upload (chunked upload)
+test_large_file_upload() {
+    print_header "Test 6: Large File Upload (Chunked)"
+    
+    # Create a large test file (200MB)
+    print_info "Creating 200MB test file..."
+    dd if=/dev/urandom of=./backups/large_test.dat bs=1M count=200 2>/dev/null
+    
+    print_info "Uploading large file to GCS..."
+    ./dbbackup cloud upload \
+        ./backups/large_test.dat \
+        "gs://$BUCKET_NAME/large/large_test.dat?endpoint=$GCS_ENDPOINT"
+    
+    if [ $? -eq 0 ]; then
+        print_success "Large file uploaded successfully (chunked)"
+        
+        # Verify file exists and has correct size
+        print_info "Downloading large file..."
+        ./dbbackup cloud download \
+            "gs://$BUCKET_NAME/large/large_test.dat?endpoint=$GCS_ENDPOINT" \
+            ./backups/large_test_downloaded.dat
+        
+        if [ $? -eq 0 ]; then
+            ORIGINAL_SIZE=$(stat -f%z ./backups/large_test.dat 2>/dev/null || stat -c%s ./backups/large_test.dat)
+            DOWNLOADED_SIZE=$(stat -f%z ./backups/large_test_downloaded.dat 2>/dev/null || stat -c%s ./backups/large_test_downloaded.dat)
+            
+            if [ "$ORIGINAL_SIZE" -eq "$DOWNLOADED_SIZE" ]; then
+                print_success "Downloaded file size matches original ($ORIGINAL_SIZE bytes)"
+            else
+                print_error "File size mismatch (original: $ORIGINAL_SIZE, downloaded: $DOWNLOADED_SIZE)"
+            fi
+        else
+            print_error "Large file download failed"
+        fi
+        
+        # Cleanup
+        rm -f ./backups/large_test.dat ./backups/large_test_downloaded.dat
+    else
+        print_error "Large file upload failed"
+        return 1
+    fi
+}
+
+# Test 7: Delete from GCS
+test_delete_backup() {
+    print_header "Test 7: Delete Backup from GCS"
+    
+    ./dbbackup cloud delete "gs://$BUCKET_NAME/mysql/backup1.sql?endpoint=$GCS_ENDPOINT"
+    
+    if [ $? -eq 0 ]; then
+        print_success "Deleted backup from GCS"
+        
+        # Verify deletion
+        if ! ./dbbackup cloud list "gs://$BUCKET_NAME/mysql/?endpoint=$GCS_ENDPOINT" | grep -q "backup1.sql"; then
+            print_success "Verified backup was deleted"
+        else
+            print_error "Backup still exists after deletion"
+        fi
+    else
+        print_error "Failed to delete backup"
+        return 1
+    fi
+}
+
+# Test 8: Cleanup old backups
+test_cleanup() {
+    print_header "Test 8: Cleanup Old Backups"
+    
+    # Create multiple backups with different timestamps
+    for i in {1..5}; do
+        ./dbbackup backup postgres \
+            --host $POSTGRES_HOST \
+            --port $POSTGRES_PORT \
+            --user $POSTGRES_USER \
+            --password $POSTGRES_PASS \
+            --database $POSTGRES_DB \
+            --output "./backups/pg_cleanup_$i.sql" \
+            --cloud "gs://$BUCKET_NAME/cleanup/backup_$i.sql?endpoint=$GCS_ENDPOINT"
+        sleep 1
+    done
+    
+    print_success "Created 5 test backups"
+    
+    # Cleanup, keeping only 2
+    ./dbbackup cleanup "gs://$BUCKET_NAME/cleanup/?endpoint=$GCS_ENDPOINT" --keep 2
+    
+    if [ $? -eq 0 ]; then
+        print_success "Cleanup completed"
+        
+        # Count remaining backups
+        COUNT=$(./dbbackup cloud list "gs://$BUCKET_NAME/cleanup/?endpoint=$GCS_ENDPOINT" | grep -c "backup_")
+        if [ "$COUNT" -le 2 ]; then
+            print_success "Verified cleanup (kept 2 backups)"
+        else
+            print_error "Cleanup failed (expected 2 backups, found $COUNT)"
+        fi
+    else
+        print_error "Cleanup failed"
+        return 1
+    fi
+}
+
+# Main test execution
+main() {
+    print_header "Google Cloud Storage (fake-gcs-server) Integration Tests"
+    
+    # Setup
+    build_dbbackup
+    start_services
+    create_test_data
+    
+    # Run tests
+    test_postgres_backup
+    test_mysql_backup
+    test_list_backups
+    test_verify_backup
+    test_restore_from_gcs
+    test_large_file_upload
+    test_delete_backup
+    test_cleanup
+    
+    # Cleanup
+    print_header "Cleanup"
+    rm -rf ./backups
+    
+    # Summary
+    print_header "Test Summary"
+    echo -e "${GREEN}Passed: $TESTS_PASSED${NC}"
+    echo -e "${RED}Failed: $TESTS_FAILED${NC}"
+    
+    if [ $TESTS_FAILED -eq 0 ]; then
+        print_success "All tests passed!"
+        stop_services
+        exit 0
+    else
+        print_error "Some tests failed"
+        print_info "Leaving services running for debugging"
+        print_info "Run 'docker-compose -f docker-compose.gcs.yml down' to stop services"
+        exit 1
+    fi
+}
+
+# Run main
+main