Database Backup Container

A lightweight Alpine-based Docker container for backing up MariaDB and PostgreSQL databases using Restic.

Overview

This container automatically detects the database type (MariaDB or PostgreSQL) in a target container and creates backups using Restic. It supports backing up databases from other Docker containers by executing dump commands inside them.

Features

• Multi-database support: Automatically detects and backs up MariaDB or PostgreSQL databases
• Restic integration: Uses Restic for efficient, encrypted, and deduplicated backups
• Docker-in-Docker: Can access and backup databases from other containers
• Lightweight: Based on Alpine Linux for minimal footprint

Prerequisites

• Docker with socket access (/var/run/docker.sock)
• Target container with either MariaDB or PostgreSQL client tools
• Restic repository (local, S3, B2, etc.)

Environment Variables

Required

Variable	Description
CONTAINER	Name of the Docker container where the database is running
RESTIC_PASSWORD	Password for the Restic repository
RESTIC_REPOSITORY	Restic repository URL (e.g., s3:s3.amazonaws.com/bucket, /data/backups)

Database-specific

For MariaDB containers:

Variable	Description
MARIADB_ROOT_PASSWORD	Root password for MariaDB

For PostgreSQL containers:

Variable	Description
DB_USER	PostgreSQL username
PGPASSWORD	PostgreSQL password
DB_NAME	PostgreSQL database name

Usage

Basic Usage

docker run --rm \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e CONTAINER=my-mariadb-container \
  -e RESTIC_PASSWORD=my-secret-password \
  -e RESTIC_REPOSITORY=s3:s3.amazonaws.com/my-backup-bucket \
  -e MARIADB_ROOT_PASSWORD=db-password \
  gitea.ceperka.net/rosti/db-backup:latest

With Docker Compose

version: '3.8'

services:
  database:
    image: mariadb:latest
    environment:
      MARIADB_ROOT_PASSWORD: secretpassword
      MARIADB_DATABASE: myapp
    volumes:
      - db_data:/var/lib/mysql

  backup:
    image: gitea.ceperka.net/rosti/db-backup:latest
    depends_on:
      - database
    environment:
      CONTAINER: database
      RESTIC_PASSWORD: my-backup-password
      RESTIC_REPOSITORY: /backups
      MARIADB_ROOT_PASSWORD: secretpassword
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - ./backups:/backups

volumes:
  db_data:

Scheduled Backups with Cron

To run backups on a schedule, you can use cron or a container orchestrator:

# Add to crontab for daily backups at 2 AM
0 2 * * * docker run --rm -v /var/run/docker.sock:/var/run/docker.sock -e CONTAINER=my-db -e RESTIC_PASSWORD=pass -e RESTIC_REPOSITORY=/backups -e MARIADB_ROOT_PASSWORD=dbpass gitea.ceperka.net/rosti/db-backup:latest

Kubernetes CronJob

apiVersion: batch/v1
kind: CronJob
metadata:
  name: database-backup
spec:
  schedule: "0 2 * * *"  # Daily at 2 AM
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: backup
            image: gitea.ceperka.net/rosti/db-backup:latest
            env:
            - name: CONTAINER
              value: "my-database-pod"
            - name: RESTIC_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: backup-secrets
                  key: restic-password
            - name: RESTIC_REPOSITORY
              value: "s3:s3.amazonaws.com/my-backup-bucket"
            - name: MARIADB_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: db-secrets
                  key: root-password
            volumeMounts:
            - name: docker-sock
              mountPath: /var/run/docker.sock
          volumes:
          - name: docker-sock
            hostPath:
              path: /var/run/docker.sock
          restartPolicy: OnFailure

Backup File Naming

Backups are stored with the following naming convention:

• MariaDB: mariadb_[CONTAINER]_[DB_NAME].sql
• PostgreSQL: pgsql_[CONTAINER]_[DB_NAME].sql

Supported Restic Repositories

This container supports all Restic repository types:

• Local: /path/to/backup/dir
• SFTP: sftp:user@host:/path/to/repo
• S3: s3:s3.amazonaws.com/bucket
• Azure: azure:container:/path
• Google Cloud: gs:bucket:/path
• Backblaze B2: b2:bucket:/path
• REST: rest:http://host:8000/repo

Building

# Build the image
task build

# Tag as latest
task tag-latest

# Push to registry
task push

Or manually:

docker build -t gitea.ceperka.net/rosti/db-backup:dev .

Troubleshooting

Common Issues

1. "Docker is not available"

   • Ensure Docker socket is mounted: -v /var/run/docker.sock:/var/run/docker.sock
   • Check Docker daemon is running

2. "Unsupported database type"

   • Verify the target container has mariadb-dump or pg_dump installed
   • Check container name is correct

3. Authentication errors

   • Verify database credentials are correct
   • Ensure environment variables are properly set

Debug Mode

To debug issues, you can run the container interactively:

docker run -it --rm \
  -v /var/run/docker.sock:/var/run/docker.sock \
  --entrypoint /bin/sh \
  gitea.ceperka.net/rosti/db-backup:latest

Security Considerations

• Store sensitive environment variables in secrets (Kubernetes secrets, Docker secrets, etc.)
• Use least-privilege access for Docker socket when possible
• Regularly rotate Restic repository passwords
• Consider using encrypted storage for backup repositories

License

This project is licensed under the MIT License.