Can't create directories in the wp-content/

[taraspos]

Here in Dockerfile https://github.com/docker-library/wordpress/blob/master/php7.4/fpm/Dockerfile#L88 directories are being pre-created, to set permissions on the folders for future mounts.

I wanted to add one more folder cache. But it was mysteriously gone from the container.

For example image like:

FROM wordpress:5.5.1-php7.4-fpm 
RUN mkdir /var/www/html/wp-content/cache/ && ls -al /var/www/html/wp-content/
RUN ls -al /var/www/html/wp-content/

Resulted in the following build log:

Step 1/3 : FROM wordpress:5.5.1-php7.4-fpm
 ---> 58a200fd0768
Step 2/3 : RUN mkdir /var/www/html/wp-content/cache/ && ls -al /var/www/html/wp-content/
 ---> Running in 68905758cdcf
total 20
drwxrwxrwx 5 www-data www-data 4096 Oct  8 13:18 .
drwxrwxrwx 3 www-data www-data 4096 Oct  8 13:18 ..
drwxr-xr-x 2 root     root     4096 Oct  8 13:18 cache
drwxrwxrwx 2 www-data www-data 4096 Sep 11 09:12 plugins
drwxrwxrwx 2 www-data www-data 4096 Sep 11 09:12 themes
Removing intermediate container 68905758cdcf
 ---> a1e985c4ad25
Step 3/3 : RUN ls -al /var/www/html/wp-content/
 ---> Running in 4ab957561104
total 16
drwxrwxrwx 4 www-data www-data 4096 Oct  8 13:18 .
drwxrwxrwx 3 www-data www-data 4096 Oct  8 13:18 ..
drwxrwxrwx 2 www-data www-data 4096 Sep 11 09:12 plugins
drwxrwxrwx 2 www-data www-data 4096 Sep 11 09:12 themes
Removing intermediate container 4ab957561104
 ---> a22fb6ca6c36
Successfully built a22fb6ca6c36

You can see, that on the step 2 directory cache is present, but on step 3 it is missing.
Apparently, this is a known bug moby/moby#3639.

Just wanted to leave this here for other people, or maybe we can come upon some better approach to pre-create some directories.

[tianon]

This would be because /var/www/html is a defined VOLUME in the base image (as you've determined, but just to be clear).

If you instead pre-create /usr/src/wordpress/wp-content/cache, then any new container should create /var/www/html at runtime when it copies /usr/src/wordpress over to /var/www/html to pre-heat the Wordpress installation.

[taraspos]

Thanks for the quick reply!

If you instead pre-create /usr/src/wordpress/wp-content/cache, then any new container should create /var/www/html at runtime when it copies /usr/src/wordpress over to /var/www/html to pre-heat the Wordpress installation.

I tried that approach, however, this doesn't solve the permissions problem because docker volumes are mounted on container start with root:root owner. Then, when docker-entrypoint.sh executed and it tries to copy /usr/src/wordpress/wp-content/cache to /var/www/html/wp-content/cache directory already exists there so permissions are not being applied as well :(

My current workaround for that is wrapping the docker-entrypoint.sh script with following code:

RUN echo "#!/bin/bash" > /docker-entrypoint.sh \
    && echo "chown -v www-data:www-data /var/www/html/wp-content/*" >> /docker-entrypoint.sh \
    && echo 'source docker-entrypoint.sh' >> /docker-entrypoint.sh \
    && chmod 755 /docker-entrypoint.sh

ENTRYPOINT ["/docker-entrypoint.sh"]
CMD ["php-fpm"]

this way permissions are enforced on container start.

[wglambert]

With proper permissions I don't encounter any issues with mounting the folder to /usr/src/wordpress/wp-content/cache

$ mkdir cache && echo test > cache/test_file && chmod -R 755 cache

$ docker-compose up -d
Creating network "test_default" with the default driver
Creating volume "test_wordpress" with default driver
Creating volume "test_db" with default driver
Creating test_db_1        ... done
Creating test_wordpress_1 ... done

$ docker exec test_wordpress_1 ls -l wp-content
total 4
drwxr-xr-x 2 www-data www-data 23 Oct  8 17:22 cache
-rw-r--r-- 1 www-data www-data 28 Jan  8  2012 index.php
drwxr-xr-x 3 www-data www-data 55 Sep  1 18:54 plugins
drwxr-xr-x 5 www-data www-data 88 Sep  1 18:54 themes

$ docker exec test_wordpress_1 ls -l wp-content/cache
total 4
-rwxr-xr-x 1 www-data www-data 5 Oct  8 17:22 test_file

docker-compose.yml

version: '3.1'

services:

  wordpress:
    image: wordpress
    restart: always
    ports:
      - 8080:80
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_USER: exampleuser
      WORDPRESS_DB_PASSWORD: examplepass
      WORDPRESS_DB_NAME: exampledb
    volumes:
      - wordpress:/var/www/html
      - /test/cache:/usr/src/wordpress/wp-content/cache

  db:
    image: mysql:5.7
    restart: always
    environment:
      MYSQL_DATABASE: exampledb
      MYSQL_USER: exampleuser
      MYSQL_PASSWORD: examplepass
      MYSQL_RANDOM_ROOT_PASSWORD: '1'
    volumes:
      - db:/var/lib/mysql

volumes:
  wordpress:
  db:

[taraspos]

Hey @wglambert , my use-case is a bit different.

I'm running wordpress on ECS with shared EFS filesystem mounted to the /var/www/html/wp-content.
However, EFS is quite slow for frequent reads. So I'm mounting wp-content/plugins, wp-content/themes and wp-content/cache as docker volumes for faster reads.

Now consider the following

docker-compose.yml

version: '3.1'

services:

  wordpress:
    image: wordpress
    restart: always
    ports:
      - 8080:80
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_USER: exampleuser
      WORDPRESS_DB_PASSWORD: examplepass
      WORDPRESS_DB_NAME: exampledb
    volumes:
      - wordpress:/var/www/html
      - wordpress-cache:/var/www/html/wp-content/cache

  db:
    image: mysql:5.7
    restart: always
    environment:
      MYSQL_DATABASE: exampledb
      MYSQL_USER: exampleuser
      MYSQL_PASSWORD: examplepass
      MYSQL_RANDOM_ROOT_PASSWORD: '1'
    volumes:
      - db:/var/lib/mysql

volumes:
  wordpress:
  wordpress-cache:
  db:

Then lets simulate some behavior of w3tc plugin which tries to create the wp-content/cache/tmp directory:

$ docker exec -it -u www-data tmp_wordpress_1 mkdir /var/www/html/wp-content/cache/tmp
mkdir: cannot create directory '/var/www/html/wp-content/cache/tmp': Permission denied

[tianon]

Ah interesting -- I can't find anything in the "codex" specifically documenting the use of this directory, but I did find a lot of instances of users/pros about removing it for various reasons, and https://github.com/WordPress/WordPress/blob/5f2f199a75eb515b25900af795ac2a1004583915/wp-includes/rss.php#L721 which appears to be a "core" usage of it for certain circumstances.

I'm not sure why it's not included in the official release tarballs as an empty directory, but I'd be +1 to having our image pre-create it with the appropriate ownership (for the same reason / in the same place as we do other directories inside wp-content).

[tianon]

More specifically, updating the following:

wordpress/Dockerfile-debian.template

Lines 88 to 93 in 598769a

	# pre-create wp-content (and single-level children) for folks who want to bind-mount themes, etc so permissions are pre-created properly instead of root:root
	mkdir wp-content; \
	for dir in /usr/src/wordpress/wp-content/*/; do \
	dir="$(basename "${dir%/}")"; \
	mkdir "wp-content/$dir"; \
	done; \

To something like:

# pre-create wp-content (and single-level children) for folks who want to bind-mount themes, etc so permissions are pre-created properly instead of root:root
	mkdir wp-content; \
	for dir in /usr/src/wordpress/wp-content/*/ cache; do \
		dir="$(basename "${dir%/}")"; \
		mkdir "wp-content/$dir"; \
	done; \