Introduction to Docker Compose

Intermediate Docker

Mike Metzger

Data Engineering Consultant

What is Docker Compose?

Additional command-line tool for Docker
Define and manage multi-container applications
Specify containers, networking, and storage volumes in a single file
- compose.yml or compose.yaml
- Older compose files may be named docker-compose.yaml
Easy to share / demo applications

Example compose.yaml

# Define the services
services:

  # Define the container(s), by name
  webapp:
    image: "webapp"

    # Optionally, define the port forwarding
    ports:
      - "8000:5000"

  # Define any other containers required
  redis:
    image: "redis:alpine"

Starting an application

docker compose up
- On older systems, docker-compose up
- docker compose -f <yaml> up
- docker compose up -d

$ docker compose up

[+] Running 2/0
 ? Network composetest_default    Created
 ? Container composetest-redis-1  Created                                                                                                             0.0s
 ? Container composetest-web-1    Created                                                                                                             0.0s
Attaching to redis-1, web-1
redis-1  | 1:C 11 Mar 2024 04:09:51.754 * oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
web-1    |  * Serving Flask app 'app.py'
web-1    |  * Running on http://127.0.0.1:5000

Checking status of applications

docker compose ls

$ docker compose ls

NAME                STATUS              CONFIG FILES
webapp              running(2)          /webapp/docker-compose.yml

Stopping an application

docker compose down
- docker-compose down
- docker compose -f <yaml> down

$ docker compose down

[+] Running 3/3
 ? Container composetest-redis-1  Removed                                                                                                             0.1s
 ? Container composetest-web-1    Removed                                                                                                            10.1s
 ? Network composetest_default    Removed                                                                                                             0.1s

Let's practice!

Intermediate Docker