docker-compose-basics

Docker Compose lets you define multiple services in a single YAML file, then orchestrate them together. Write a docker-compose.yml specifying your web, API, and database services with their configurations, then run docker compose up to start all containers at once with networking and volumes automatically managed.

Docker Compose is a tool for defining and running multi-container Docker applications using YAML configuration. You need it when managing interconnected services—like a web server, API backend, and database—that must run together with shared networking, persistent storage, and coordinated startup.

Define each service under the services key with image, ports, environment variables, and volume mounts. Use the networks section to create custom networks for inter-service communication, and the volumes section to define persistent storage. Services automatically connect through the default network with DNS resolution by service name.

Yes. Use the environment key within each service to inject variables, or reference an .env file. Add a healthcheck block specifying the command, interval, timeout, and retry count to monitor service readiness and prevent dependent services from starting before prerequisites are healthy.

Core commands include docker compose up to start services, docker compose down to stop and remove containers, docker compose logs to view output, docker compose build to rebuild images, and docker compose scale to run multiple instances of a service for load distribution.

Yes, Docker Compose configuration relies on YAML syntax, which uses indentation and key-value pairs to structure service definitions. Learning basic YAML—proper spacing, nested objects, and lists—is essential for writing valid docker-compose.yml files that Docker can parse and execute correctly.