docker-patterns

Define services in docker-compose.yml with build targets, port mappings, bind mounts for hot reload, and healthchecked dependencies like Postgres. Use an anonymous volume for node_modules so container dependencies are not overwritten by the host bind mount.

Services on the same Compose network resolve each other by service name via built-in DNS. For example, the app container connects to Postgres using the hostname db and to Redis using the hostname redis.

Use a single multi-stage Dockerfile with separate dev, build, and production stages. Target the dev stage in Compose for hot reload, and the production stage for a minimal image running as a non-root user.

Load secrets from a gitignored .env file via env_file or inherit them from the host environment, and use Docker secrets in Swarm mode. Never hardcode credentials in the Dockerfile or commit them to docker-compose.yml.

Containers are ephemeral, so data written inside them disappears on removal. Mount a named volume such as pgdata to the database data directory to persist data across container restarts.

Docker Compose is designed for single-host local development, not production orchestration. For production multi-container workloads, use Kubernetes, ECS, or Docker Swarm instead.