docker wordpress wp-config not found

Question

I am new to docker, but I'm starting to understand the basics. Basically with a docker-compose setup I am getting this error preventing the website from running:

wordpress_1  | sed: can't read wp-config*: No such file or directory

My setup is pretty simple:

// docker compose file 
version: '3'

services:
  db:
    image: mysql:5.7
    volumes:
      - db_data:/var/lib/mysql
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: password
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wordpress
      MYSQL_PASSWORD: wordpress
    networks:
      - wpsite
  wordpress:
    depends_on:
      - db
    image: mycustomwordpressimage
    ports:
      - '8000:80'
    restart: always
    volumes: ['./:/var/www/html']
    environment:
      WORDPRESS_DB_HOST: db:3306
      WORDPRESS_DB_USER: wordpress
      WORDPRESS_DB_PASSWORD: wordpress
      WORDPRESS_DB_NAME: wordpress
    networks:
      - wpsite
networks:
  wpsite:
volumes:
  db_data:

I think it's something to do with my custom wp image which uses a custom wordpress image with my custom theme. Maybe i have to put env vars here?

// mycustomwordpressimage Dockerfile ( just a repo in the folder of the theme )
FROM wordpress:5-php7.4-fpm

COPY . /var/www/html/wp-content/themes/

if it's something with my syntax, or doing something stupid, please let me know I have no idea.

Answer 1

You don't need to create a custom image for this, if you just mount that directory everything will work.

Example:

services:
  wordpress:
    image: wordpress:5-php7.4-fpm
    ...
    volumes:
      - ./themes/:/var/www/html/wp-content/themes/

If you really want/need to create a custom image, you will have to modify/create a wrapper around docker-entrypoint.sh ( https://github.com/docker-library/wordpress/blob/master/php7.4/fpm/docker-entrypoint.sh ), this script is what is causing that error. On the first run it installs wordpress in /var/www/html , which is a declared volume ( https://github.com/docker-library/wordpress/blob/master/php7.4/fpm/Dockerfile#L97 ).