Docker as automation,

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Avast ye! This be a machine-translated text, an’ it may contain errors, aye!

Docker be simplifies the launchin’ o’ applications. Instead o’ installin’ and configurin’ software manually on a server, ye define all in configuration files. The result be reproducible, portable, and quick to set up.

What be Docker Compose?

With Docker Compose, ye define multiple services in a single file (docker-compose.yml). Each service be a container with its own configuration, aye.

services:
  web:
    image: nginx:latest
    ports:
      - "80:80"
  grafana:
    image: grafana/grafana:latest
    ports:
      - "3000:3000"
# Aye, this be the web service, matey!
# Shiver me timbers, 'tis Grafana we be havin' here!

One command sets it all up:

docker compose up -d
# Starter tjenestene i bakgrunnen, arr!

Need ye be shiftin’ the service to another server? Copy the file an’ run the same command. All be identical, aye.

Why Be This Automation?

Consider the difference:

Manual Setup With Docker Compose
Install Nginx manually image: nginx:latest
Configure ports ports: "80:80"
Install Grafana manually image: grafana/grafana:latest
Document all the steps All be documented in the .yml file
Repeat all on the next server docker compose up -d

The Docker Compose file be the documentation. It describes exactly which services be runnin’, which ports they use, and how they be configured.

Useful Docker Commands, Ye Scallywags!

Command What it does, Arrr!
docker compose up -d Starts all the services in the shadows
docker compose down Stops and scuttles all the containers
docker compose logs -f Keeps a weather eye on the logs in real-time
docker compose pull Fetches the latest booty for all images
docker compose restart Reboots all the services, matey!
docker ps Shows which containers be sailin’

Volumes: Stashin’ Data Outside the Hold

Containers be temporary, aye. If ye be sendin’ a container to Davy Jones’ locker, all its contents be vanishin’ with it. To keep yer treasure safe, we use volumes:

services:
  database:
    image: postgres:16
    ports:
      - "5432:5432"
    environment:
      POSTGRES_PASSWORD: secret # secret, matey
    volumes:
      - db-data:/var/lib/postgresql/data

volumes:
  db-data:

Here be where the database files be stored in a volume called db-data. Even if ye be deletin’ and recreatin’ the container, the data still remains, aye.

Updatin’ the Services

Updatin’ a Docker service be a simple task, aye:

# Fetch the latest version, aye!
docker compose pull

# Restart with the new version, shiver me timbers!
docker compose up -d

Compare this to updatin’ software ye installed yerself, where ye might have to download, configure, an’ pray nothin’ breaks!

Easy Quest 1 - Set up Nginx with Docker Compose

Forge a docker-compose.yml that runs an Nginx webserver:

  1. Carve out a new folder and create the docker-compose.yml file
  2. Define a service with image: nginx:latest on port 80
  3. Run docker compose up -d
  4. Set sail to http://localhost in yer browser

Medium Task 2 - Add a new service to the crew

Expand docker-compose.yml from task 1 with an extra service. For example:

Set sail with docker compose up -d and see if both services be runnin’ at the same time.

Summary

  • Docker Compose allows ye to define multiple services in a single file
  • The Compose file be both configuration and documentation
  • Volumes store data outside the container so it survives restarts
  • Updating be docker compose pull + docker compose up -d
  • Docker makes it easy to move services between servers