Advanced Docker Workshop

1. Basic Services

We start with the most fundamental part of a docker-compose.yml file: defining services. Here, we define two services: a database (db) and an application (app).

version: "3"
services:
  db:
    image: postgres:15
  app:
    image: myapp:latest

2. Adding Ports

Next, we expose necessary ports to allow communication between containers and external systems.

version: "3"
services:
  db:
    image: postgres:15
    ports:
      - "5432:5432"
  app:
    image: myapp:latest
    ports:
      - "8080:80"

3. Adding Networks Inside Services

We define internal networks for communication between services.

version: "3"
services:
  db:
    image: postgres:15
    ports:
      - "5432:5432"
    networks:
      - backend
  app:
    image: myapp:latest
    ports:
      - "8080:80"
    networks:
      - backend

4. Defining the Main Networks section

A network outside the services section provides better control.

version: "3"
services:
  db:
    image: postgres:15
    ports:
      - "5432:5432"
    networks:
      - mynetwork
  app:
    image: myapp:latest
    ports:
      - "8080:80"
    networks:
      - mynetwork

networks:
  mynetwork:

5. Types of Networks

Different network types can be defined.

networks:
  mynetwork:
    driver: bridge  # Default option
  myoverlay:
    driver: overlay
  myhost:
    driver: host

6. Adding Volumes Inside Services

Volumes store persistent data.

services:
  db:
    image: postgres:15
    volumes:
      - ./db_data:/var/lib/postgresql/data

volumes:
  db_data:

7. Defining a Main Volumes Section

volumes:
  db_data:
    driver: local

8. Adding Restart Policies

Ensuring services restart under different conditions.

services:
  db:
    image: postgres:15
    restart: unless-stopped
  app:
    image: myapp:latest
    restart: always

9. Other Common Start Options

Other useful configurations.

services:
  db:
    image: postgres:15
    environment:
      - POSTGRES_USER=admin
      - POSTGRES_PASSWORD=secret
      - POSTGRES_DB=mydatabase
    depends_on:
      - app

10. Environment Variables for Credentials

Using environment variables improves security.

services:
  db:
    image: postgres:15
    environment:
      - POSTGRES_USER=${DB_USER}
      - POSTGRES_PASSWORD=${DB_PASS}
      - POSTGRES_DB=${DB_NAME}

11. Using a .env File

We replace hardcoded credentials with variables stored in a .env file.

.env file:

DB_USER=admin
DB_PASS=secret
DB_NAME=mydatabase

docker-compose.yml:

services:
  db:
    image: postgres:15
    environment:
      - POSTGRES_USER=${DB_USER}
      - POSTGRES_PASSWORD=${DB_PASS}
      - POSTGRES_DB=${DB_NAME}

Now we have some fun

We install Joplin
http://rino.kozow.com/devops/posts/replace-onenote-self–host-joplin-docker-container-in-proxmox-lxc-container/

The joplin docker compose file

Run these commands :

sudo su -

mkdir /opt/stacks/joplin -p

cd /opt/stacks/joplin/

nano compose.yaml

put this in the file:

version: '3'
services:
    db:
        image: postgres:16
        volumes:
            - ./data/postgres:/var/lib/postgresql/data
        ports:
            - "5432:5432"
        restart: unless-stopped
        environment:
            - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
            - POSTGRES_USER=${POSTGRES_USER}
            - POSTGRES_DB=${POSTGRES_DB}
    app:
        image: joplin/server:latest
        depends_on:
            - db
        ports:
            - "22300:22300"
        restart: unless-stopped
        environment:
            - APP_PORT=22300
            - APP_BASE_URL=${APP_BASE_URL}
            - DB_CLIENT=pg
            - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
            - POSTGRES_DATABASE=${POSTGRES_DB}
            - POSTGRES_USER=${POSTGRES_USER}
            - POSTGRES_PORT=5432
            - POSTGRES_HOST=db

Run this command:

nano .env

Put this in the file

POSTGRES_PASSWORD=testing123
POSTGRES_USER=joplin
POSTGRES_DB=joplindb
APP_BASE_URL=http://192.168.68.105:22300

Lets start this container

run this command:

docker compose up

we can see the server is running in the browser

http://your-server-ip:22300

http://tiger.loseyourip.com:22300/

Default email : admin@localhost

Defailt password : admin