DB Tech WordPress for Pi Home Server

gistfile1.txt

version: '2.1'

services:

  wordpress:
    image: wordpress
    restart: always
    ports:
      - 84:80
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_USER: exampleuser
      WORDPRESS_DB_PASSWORD: examplepass
      WORDPRESS_DB_NAME: exampledb
    volumes:
      - /srv/dev-disk-by-label-Files/Config/WordPress:/var/www/html
    links:
      - db:db

  db:
    image: yobasystems/alpine-mariadb:latest
    restart: always
    environment:
      MYSQL_DATABASE: exampledb
      MYSQL_USER: exampleuser
      MYSQL_PASSWORD: examplepass
      MYSQL_RANDOM_ROOT_PASSWORD: '1'
    volumes:
      - /srv/dev-disk-by-label-Files/Databases/WordPress:/var/lib/mysql

Any updates on this? @phamleduy04's solution no longer works (tested on x86 based system), am getting the "Error establishing a database connection" error.
Adding

volumes:
  wordpress:
  db:

to the bottom, also does nothing.

So I tried this on x86 based system and confirm it worked

version: '3.6'

services:

  wordpress:
    image: wordpress
    restart: always
    ports:
      - 84:80
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_USER: exampleuser
      WORDPRESS_DB_PASSWORD: examplepass
      WORDPRESS_DB_NAME: exampledb
    volumes:
      - ./wp:/var/www/html
    links:
      - db:db

  db:
    image: docker.io/bitnami/mariadb:10.7
    environment:
      MARIADB_ROOT_PASSWORD: examplepass
      MARIADB_USER: exampleuser
      MARIADB_PASSWORD: examplepass
      MARIADB_DATABASE: exampledb
    volumes:
      - './mariadb_data:/bitnami/mariadb'
    healthcheck:
      test: ['CMD', '/opt/bitnami/scripts/mariadb/healthcheck.sh']
      interval: 15s
      timeout: 5s
      retries: 6

Volumes start with ./ means it will create a folder in the folder where the docker-compose.yml is stored. If you use Portainer or something else you should specify the full path, or use docker volumes.

Check the MariaDB logs, I got some permission errors like this
mkdir: cannot create directory '/bitnami/mariadb': Permission denied
It can be fixed by using this command

sudo chown -R 1001:1001 <mariadb_folder>

What do I put for the volumes: variable if I am not using Open Media Vault. Do I create a volume in portainer? I am trying to follow along from the youtube tutorial. Please explain as if you are explaining to someone who has no experience navigating file systems in linux/raspbian.