Docker Database Configuration Skill

Overview

This skill configures database containers following best practices for:

• Security (passwords, network isolation)

• Persistence (named volumes)

• Health checks

• Initialization scripts

• Backup and restore

Supported Databases

• PostgreSQL

• MySQL/MariaDB

• MongoDB

• Redis

Process

1. Consult Documentation

Read 05-databases.md for:

• Image versions

• Environment variables

• Health check configurations

• Volume paths

• Initialization patterns

2. Generate Configuration

PostgreSQL Configuration

services: postgres: image: postgres:16-alpine container_name: postgres restart: unless-stopped shm_size: 256mb environment: POSTGRES_USER: ${DB_USER:-appuser} POSTGRES_PASSWORD: ${DB_PASSWORD} POSTGRES_DB: ${DB_NAME:-appdb} volumes: - postgres_data:/var/lib/postgresql/data - ./init-scripts:/docker-entrypoint-initdb.d ports: - "127.0.0.1:5432:5432" networks: - database healthcheck: test: ["CMD-SHELL", "pg_isready -U ${DB_USER:-appuser} -d ${DB_NAME:-appdb}"] interval: 10s timeout: 5s retries: 5 start_period: 30s

volumes: postgres_data:

networks: database: internal: true

MySQL Configuration

services: mysql: image: mysql:8.0 container_name: mysql restart: unless-stopped environment: MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD} MYSQL_DATABASE: ${DB_NAME} MYSQL_USER: ${DB_USER} MYSQL_PASSWORD: ${DB_PASSWORD} volumes: - mysql_data:/var/lib/mysql - ./init-scripts:/docker-entrypoint-initdb.d ports: - "127.0.0.1:3306:3306" command: > --default-authentication-plugin=mysql_native_password --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci healthcheck: test: ["CMD", "mysqladmin", "ping", "-h", "localhost", "-u", "root", "-p${MYSQL_ROOT_PASSWORD}"] interval: 10s timeout: 5s retries: 5

volumes: mysql_data:

MongoDB Configuration

services: mongodb: image: mongo:7 container_name: mongodb restart: unless-stopped environment: MONGO_INITDB_ROOT_USERNAME: ${MONGO_USER} MONGO_INITDB_ROOT_PASSWORD: ${MONGO_PASSWORD} MONGO_INITDB_DATABASE: ${MONGO_DB} volumes: - mongo_data:/data/db - mongo_config:/data/configdb ports: - "127.0.0.1:27017:27017" healthcheck: test: ["CMD", "mongosh", "--eval", "db.adminCommand('ping')"] interval: 10s timeout: 5s retries: 5

volumes: mongo_data: mongo_config:

Redis Configuration

services: redis: image: redis:7-alpine container_name: redis restart: unless-stopped command: > redis-server --appendonly yes --maxmemory 256mb --maxmemory-policy allkeys-lru --requirepass ${REDIS_PASSWORD} volumes: - redis_data:/data ports: - "127.0.0.1:6379:6379" healthcheck: test: ["CMD", "redis-cli", "-a", "${REDIS_PASSWORD}", "ping"] interval: 10s timeout: 5s retries: 5

volumes: redis_data:

Connection Strings

PostgreSQL

DATABASE_URL=postgresql://user:password@db:5432/dbname

MySQL

DATABASE_URL=mysql://user:password@db:3306/dbname

MongoDB

MONGO_URI=mongodb://user:password@mongodb:27017/dbname?authSource=admin

Redis

REDIS_URL=redis://:password@redis:6379

Backup Commands

PostgreSQL

docker compose exec -T db pg_dumpall -c -U appuser > backup.sql

MySQL

docker compose exec -T db mysqldump -u root -p"$PASS" --all-databases > backup.sql

MongoDB

docker compose exec -T db mongodump --archive --gzip > backup.gz

Redis (if persistence enabled)

docker compose exec redis redis-cli -a "$PASS" BGSAVE

Restore Commands

PostgreSQL

docker compose exec -T db psql -U appuser -d appdb < backup.sql

MySQL

docker compose exec -T db mysql -u root -p"$PASS" < backup.sql

MongoDB

docker compose exec -T db mongorestore --archive --gzip < backup.gz

Best Practices

• Always use named volumes for data persistence

• Bind to localhost only (127.0.0.1) unless external access needed

• Use internal networks to isolate database traffic

• Implement health checks for dependency management

• Store credentials in .env or Docker secrets

• Use initialization scripts for schema setup

• Regular backups before any risky operations