docker-compose.yaml

This file is used set up the configuration setting for containerizing our application.

version: "3.5"

services:
  database:
        ...
  server:
        ...

creates 2 services, that are basically docker images.
one is for the database and other for the server

database image

database:
    image: postgres
        restart: always
        environment:
            - POSTGRES_USER=postgres
            - POSTGRES_PASSWORD=postgres
        ports:
            - "5432:5432"
        volumes:
            - ./container/init.sql:/docker-entrypoint-initdb.d/init.sql
            - data:/var/lib/postgresql/data

image: standard docker image for postgres
enviroment: setting up environment variables for initializing the postgres db
ports: standard mapping of ports
volumes: standard way of initializing so that data persists even when the container is made to restart.

server image

server:
    build:
        context: .
        dockerfile: container/Dockerfile
    restart: always
    depends_on:
        - database
    networks:
        - default
    ports:
        - "80"

build:
- context: specifies the directory’s relative location that is to be containarized
- dockerfile: location of the Dockerfile that contains config settings for the image to be built
depends_on: depends on the image of database on the container
networks & ports standard configuration

volumes:
  data:

this creates a memory space outside the container that will be mapped with the database inside the container for the purpose of making the data persist even when the container is made to restart.
the mapping is shown with this line of code : data:/var/lib/postgresql/data .

# network with subnet configuration
networks:
  default:
      driver: bridge
      ipam:
          driver: default
          config:
              - subnet: "192.168.3.0/24"
                # gateway: "192.168.3.1"

this is a standard code to limit the choice of IP-addresses that our container takes.
the subnet range is specified by - subnet: "192.168.3.0/24"

REFERENCES