Docker, howdy as automation

This here’s a machine-translated text that might contain errors!

Docker makes deployin’ applications simpler than a Sunday mornin’. Instead of installin’ and configurin’ software by hand on a server, ya define everythin’ in configuration files. The result is reproducible, portable, and quick to get up and runnin’.

What in tarnation is Docker Compose?

With Docker Compose, ya define a whole mess o’ services in a single file (docker-compose.yml). Each service is a container with its own setup, see?

services:
  web:
    image: nginx:latest
    ports:
      - "80:80"
  grafana:
    image: grafana/grafana:latest
    ports:
      - "3000:3000"

One command sets up ever’thin’:

docker compose up -d
# Starter alle tjenester i bakgrunnen.
# Starts all services in the background.

Need ta move the service to another server? Copy the file and run the same command. Everything’s identical.

Why This Here’s Automation?

Now, 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	Everything’s documented in the `.yml` file
Repeat everything on the next server	`docker compose up -d`

That Docker Compose file is the documentation. It describes exactly which services are runnin’, what ports they use, and how they’re configured.

Handy Docker Commands

Command	What it does
`docker compose up -d`	Starts all services in the background
`docker compose down`	Stops and removes all containers
`docker compose logs -f`	Follows the logs in real time
`docker compose pull`	Pulls the latest version of all images
`docker compose restart`	Restarts all services
`docker ps`	Shows running containers

Volumes: Savin’ Yer Data Outside the Container

Containers are temporary, see? If ya go ‘n delete a container, all its contents just up ‘n vanishes. To keep yer data safe, we use volumes:

services:
  database:
    image: postgres:16
    ports:
      - "5432:5432"
    environment:
      POSTGRES_PASSWORD: hemmelig # This here is the password for the database, keep it safe, ya hear?
    volumes:
      - db-data:/var/lib/postgresql/data

volumes:
  db-data:

Here, the database files are stored in a volume called db-data. Even if ya go ‘n delete ‘n recreate the container, the data’s still there.

Updatin’ Services

Updatin’ a Docker service is plumb simple:

# Get latest version
docker compose pull

# Restart with new version
docker compose up -d

Now, reckon this here’s like fixin’ up software ya installed by yer own two hands – ya gotta download, configure, and just pray nothin’ breaks.

Task 1 - Get Nginx Runnin’ with Docker Compose

Create a docker-compose.yml to run an Nginx web server:

Make a new folder and create the file docker-compose.yml
Define a service with image: nginx:latest on port 80
Run docker compose up -d
Visit http://localhost in yer browser

Task 2 - Add a Service

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

Uptime Kuma on port 3001
Grafana on port 3000

Start everything with docker compose up -d and see that both services are runnin’ at the same time.

Summation

Docker Compose lets ya define a whole mess o’ services in a single file
The Compose file is both yer configuration and documentation, see?
Volumes store data outside the container so it survives restarts
Updatin’ is docker compose pull + docker compose up -d
Docker makes it easy to move services ‘tween servers