Add readme

Author: MaikelH

README.md

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+# postgres-backup
+
+A lightweight, automated PostgreSQL backup service that creates compressed backups and uploads them to S3-compatible storage.
+
+## Features
+
+- **Scheduled Backups**: Configurable cron-style scheduling using `robfig/cron`
+- **Compression**: Automatic gzip compression to save storage space
+- **S3 Integration**: Upload backups to AWS S3 or S3-compatible storage (MinIO, etc.)
+- **Retry Logic**: Automatic retry on S3 upload failures
+- **Local Cleanup**: Removes local backup files after successful S3 upload
+- **Flexible Configuration**: Configure via YAML file or environment variables
+- **Docker Support**: Ready-to-use Docker container
+
+## Quick Start
+
+### Using Docker
+
+```bash
+docker run -v $(pwd)/config.yaml:/app/config.yaml \
+  ghcr.io/010codingcollective/postgres-backup:latest
+```
+
+### Using Docker Compose
+
+```yaml
+version: '3.8'
+services:
+  postgres-backup:
+    image: ghcr.io/010codingcollective/postgres-backup:latest
+    volumes:
+      - ./config.yaml:/app/config.yaml
+    environment:
+      - POSTGRES_PASSWORD=your_password
+      - S3_SECRET_ACCESS_KEY=your_secret_key
+```
+
+## Configuration
+
+Configuration can be provided via:
+1. YAML file (`config.yaml`)
+2. Environment variables (highest priority)
+
+### Example Configuration
+
+```yaml
+schedule: "@daily"  # Cron format: @daily, @hourly, or "0 2 * * *"
+run_at_startup: false  # Run backup immediately on startup
+postgres_database: mydb
+postgres_user: postgres
+postgres_password: secret
+postgres_host: localhost
+postgres_port: "5432"
+postgres_extra_opts: "--schema=public --blobs"
+
+s3:
+  endpoint: ""  # Leave empty for AWS S3, or set for MinIO/S3-compatible
+  region: us-east-1
+  bucket: my-backup-bucket
+  access_key_id: AKIAIOSFODNN7EXAMPLE
+  secret_access_key: wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY
+  use_path_style: false  # Set to true for MinIO and most S3-compatible services
+```
+
+### Environment Variables
+
+All configuration can be overridden with environment variables:
+
+```bash
+SCHEDULE="@daily"
+RUN_AT_STARTUP="false"
+POSTGRES_DATABASE="mydb"
+POSTGRES_USER="postgres"
+POSTGRES_PASSWORD="secret"
+POSTGRES_HOST="localhost"
+POSTGRES_PORT="5432"
+POSTGRES_EXTRA_OPTS="--schema=public --blobs"
+S3_ENDPOINT=""
+S3_REGION="us-east-1"
+S3_BUCKET="my-backup-bucket"
+S3_ACCESS_KEY_ID="AKIAIOSFODNN7EXAMPLE"
+S3_SECRET_ACCESS_KEY="wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"
+S3_USE_PATH_STYLE="false"
+```
+
+## Schedule Format
+
+The `schedule` field uses cron format. Common examples:
+
+- `@daily` - Run once per day at midnight
+- `@hourly` - Run once per hour
+- `@every 6h` - Run every 6 hours
+- `0 2 * * *` - Run at 2:00 AM daily
+- `0 */6 * * *` - Run every 6 hours
+- `0 2 * * 0` - Run at 2:00 AM every Sunday
+
+## Backup Storage
+
+Backups are stored in S3 with the following structure:
+
+```
+s3://your-bucket/backups/{database}-backup-{timestamp}.sql.gz
+```
+
+Example: `backups/mydb-backup-20250128-020000.sql.gz`
+
+## Building from Source
+
+### Prerequisites
+
+- Go 1.23+
+- PostgreSQL client tools (`pg_dump`)
+
+### Build
+
+```bash
+go build -o pg-backup .
+```
+
+### Run
+
+```bash
+./pg-backup
+```
+
+## Building Docker Image
+
+```bash
+docker build -t postgres-backup .
+```
+
+Or using buildah:
+
+```bash
+buildah bud -f Dockerfile -t postgres-backup .
+```
+
+## How It Works
+
+1. **Scheduler** starts based on configured cron schedule
+2. **pg_dump** creates a PostgreSQL backup
+3. **Compression** compresses the backup with gzip
+4. **S3 Upload** uploads the compressed backup to S3 (with retry)
+5. **Cleanup** removes the local backup file after successful upload
+
+## Error Handling
+
+- If `pg_dump` fails, the backup job is aborted
+- If S3 upload fails, it retries once
+- If both S3 upload attempts fail, the local backup file is retained and logged
+- If S3 is misconfigured, the application fails at startup
+
+## License
+
+MIT License - see [LICENSE](LICENSE) file for details
+
+## Contributing
+
+Contributions are welcome! Please open an issue or submit a pull request.