7 Preparing Docker Compose file

So far we have been running individual 'docker' commands, which can be tedious at times as you repeat the commands.

The 'docker-compose' utility allows us to execute a 'docker-compose file' and run multiple 'docker' commands at once.

For instance, the following set of commands:

docker network create my-network 
docker run -d -p 27017:27017 --network my-network --name my-mongo         -e MONGO_INITDB_ROOT_USERNAME=admin      -e MONGO_INITDB_ROOT_PASSWORD=pass -v my-data:/var/lib/mysql/data mongo 
docker run -d -p 8081:8081   --network my-network --name my-mongo-express -e ME_CONFIG_MONGODB_ADMINUSERNAME=admin -e ME_CONFIG_MONGODB_ADMINPASSWORD=pass -e ME_CONFIG_OPTIONS_EDITORTHEME=ambiance -e ME_CONFIG_MONGODB_SERVER=my-mongo mongo-express
docker run -d -p 80:80       --network my-network --name my-app my-app:7.0

can be restructured and mapped to the following docker-compose file, my-app.yaml:

version: '3.7'

services:
  my-mongo:
    image: mongo
    ports: 
      - 27017:27017
    environment:
      - MONGO_INITDB_ROOT_USERNAME=admin     
      - MONGO_INITDB_ROOT_PASSWORD=pass 
    volumes:
      - my-data:/data/db
  my-mongo-express:
    image: mongo-express
    environment:
      - ME_CONFIG_MONGODB_ADMINUSERNAME=admin
      - ME_CONFIG_MONGODB_ADMINPASSWORD=pass
      - ME_CONFIG_OPTIONS_EDITORTHEME=ambiance
      - ME_CONFIG_MONGODB_SERVER=my-mongo
    ports:
      - 8081:8081
  my-app:
    image: my-app:7.0
    ports:
      - 80:80

volumes:
  my-data:
    driver: local

Above, data persistence is ensured for the directory /data/db on the virtual file system of the container my-mongo, so that when you removed and rerun the container, the database data is still intact.

Make sure the spacing is valid:

Do not mix tabs with spaces.
The numbers of spaces for each indentation level should be exactly the same.
For single-line keys-value pairs, there should be a space after : and - .

docker-compose inherently runs the containers within the same netowrk.

To run the the docker-compose file:

docker-compose -f my-app.yaml up

To remove the containers:

docker-compose -f my-app.yaml down

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7 Preparing Docker Compose file