docker-compose-notes.md

Docker Compose Notes

Assuming you have a Dockerfile in the current directory, you can create a docker-compose.yml file:

version: '3'

services:

  web:
    build: .
    ports:
      - '3000:3000'
    volumes:
      - .:/usr/src/app

This uses the Dockerfile in the current directory to build an image and run a container based on it, binding port 3000 on in the container to 3000 on the host machine. It also sets up the current directory as a shared volume in /usr/src/app in the container.

To run this compose file:

$ docker-compose up

You can also run this in detached mode:

$ docker-compose up -d

If you don't run in detached mode, you will see the output from the various services, each marked with the name of the service.

For example, a Rails server would look like:

web_1  | => Booting Puma
web_1  | => Rails 5.2.2 application starting in development
web_1  | => Run `rails server -h` for more startup options
web_1  | Puma starting in single mode...
web_1  | * Version 3.12.0 (ruby 2.6.0-p0), codename: Llamas in Pajamas
web_1  | * Min threads: 5, max threads: 5
web_1  | * Environment: development
web_1  | * Listening on tcp://0.0.0.0:3000

You can ctrl-c to stop the containers.

Manually stopping container

You can stop all containers with:

$ docker-compose stop

...or, you can stop a specific service

$ docker-compose stop web

Viewing running containers

$ docker-compose ps

Manually starting and restarting a service

$ docker-compose start web

$ docker-compose restart web

Viewing logs for specific service container

$ docker-compose logs -f web

Running a single command on a service

$ docker-compose exec web bin/rails g model User first_name:string last_name:string

Rebuilding images

$ docker-compose build web

Stopping with compose

Compose will start up a network, containers, volumns, etc. To clean up when you are done:

$ docker-compose down

Removing a container

$ docker-compose rm database

...or, without a confirmation dialog, pass in the -f (force) flag:

$ docker-compose rm -f database