docker-compose.yaml

# Sets the version for the docker-compose
version: '3'

# Sample local.env file before running this docker-compose file
#  export PG_HOST=my-database
#  export PG_PORT=5432
#  export PG_USER=postgres
#  export PG_PASSWORD=password
#  export PG_DB=postgres

# Define the containers required by services
services:
  # my-server is the Go API Code run by server.go
  my-server:
    # Builds the directory . (current)
    # It finds the Dockerfile and builds the image
    build: .
    # If app crashes, it will restart the container again
    restart: on-failure
    # Reads the environment from the terminal and feeds it to the container
    # Run the .env file in the terminal from which docker-compose is run
    environment:
      - DB_HOST=${PG_HOST}
      - DB_PORT=${PG_PORT}
      - DB_USER=${PG_USER}
      - DB_PASSWORD=${PG_PASSWORD}
      - DB_NAME=${PG_DB}
    # Volume defines the persistent storage on the host machine in which
    # the container is run
    volumes:
      - api:/usr/src/app/
    # Exposes the port 5000 to be accessed by port 5000 of localhost (0.0.0.0)
    # It is of the format of HOST PORT:CONTAINER PORT
    ports:
      - '5000:5000'
    # Defines the order in which the containers are to be started
    # Since this depends on my-database, my-database container will start before this one
    depends_on:
      - my-database
    # The containers running together are connected by one single network
    # We connect this app to the 'network'
    networks:
      - my-network

  # my-database pulls your database image and runs it
  # The default password is: docker
  my-database:
    # Pulls in the latest postgres installed OS
    image: postgres:latest
    # Sets the environment variables
    # Sets the username: postgres and password: password
    environment:
      - POSTGRES_USER=${PG_USER}
      - POSTGRES_PASSWORD=${PG_PASSWORD}
      - POSTGRES_DB=${PG_DB}
      - DATABASE_HOST=${PG_HOST}
    ports:
      - '5432:5432'
    # Defines the persistance storage
    # Necessary as if the container is switched off
    # Data isn't lost
    volumes:
      - ./database/init.sql:/docker-entrypoint-initdb.d/init.sql
    networks:
      - my-network
    # Healthcheck heartbeat ensures in every 5 seconds that the database is up
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U postgres"]
      interval: 5s
      timeout: 5s
      retries: 5

# Defines the volumes to be used during the entire run of these containers
volumes:
  api:

# Defines the network on which these containers are to be connected
networks:
  my-network:
    driver: bridge