Docker-compose YAML Explanation

Sample 1

version: '3'

services:

  <service name>:
    build:
      context: .
      dockerfile: ./path-to/Dockerfile
    image: <image name>:<version>
    container_name: <container name>
    restart: always
    ports:
      - <host port>:<container port>
    volumes:
      - ./file:/path-to/file:ro
      - ./path-to:/etc/path-to
    environment:
      - ENV_VAR=${TEST}
    networks:
      - sample-network
    entrypoint: ["python3", "/app/startup.py"]

networks:
  sample-network:
    name: <network name>
    driver: bridge

• Placeholder name <service name>.
• Service is built from a Dockerfile located at ./path-to/Dockerfile.
• Image result name <image name>:<version>.
• Container name <container name>.
• restart option is set to always, the container will be restarted automatically if it crashes or restarted.
• Expose a <container port> with <host port>.
• Volume ./file:/path-to/file:ro read-only file and mount some path.
• The service configured with an environment variable ENV_VAR, which is set to TEST.
• The service is connected to sample-network.
• Entrypoint ["python3", "/app/startup.py"], means the command that should be run when the container is started.
• sample-network is defined with a name <network name> and using the bridge driver.