Wordpress on Docker: Could not create directory on mounted volume

Question

Here is are the original files in the Wordpress Docker container on path /var/www/html:

$ docker exec 5b957c7b9c5ad054883694afbfb80d3c9df6707458d55011f471be0701f3890c ls -l
total 192
-rw-r--r--  1 www-data www-data   418 Sep 25  2013 index.php
-rw-r--r--  1 www-data www-data 19935 Jan  2 18:51 license.txt
-rw-r--r--  1 www-data www-data  7433 Jan 11 17:46 readme.html
-rw-r--r--  1 www-data www-data  5447 Sep 27  2016 wp-activate.php
drwxr-xr-x  9 www-data www-data  4096 May 16 21:50 wp-admin
-rw-r--r--  1 www-data www-data   364 Dec 19  2015 wp-blog-header.php
-rw-r--r--  1 www-data www-data  1627 Aug 29  2016 wp-comments-post.php
-rw-r--r--  1 www-data www-data  2764 May 29 22:19 wp-config-sample.php
-rw-r--r--  1 www-data www-data  3148 May 29 22:19 wp-config.php
drwxr-xr-x  4 www-data www-data  4096 May 16 21:50 wp-content
-rw-r--r--  1 www-data www-data  3286 May 24  2015 wp-cron.php
drwxr-xr-x 18 www-data www-data 12288 May 16 21:50 wp-includes
-rw-r--r--  1 www-data www-data  2422 Nov 21  2016 wp-links-opml.php
-rw-r--r--  1 www-data www-data  3301 Oct 25  2016 wp-load.php
-rw-r--r--  1 www-data www-data 33939 Nov 21  2016 wp-login.php
-rw-r--r--  1 www-data www-data  8048 Jan 11 05:15 wp-mail.php
-rw-r--r--  1 www-data www-data 16255 Apr  6 18:23 wp-settings.php
-rw-r--r--  1 www-data www-data 29896 Oct 19  2016 wp-signup.php
-rw-r--r--  1 www-data www-data  4513 Oct 14  2016 wp-trackback.php
-rw-r--r--  1 www-data www-data  3065 Aug 31  2016 xmlrpc.php

I am trying to start the Wordpress container with a mounted Docker volume to be able to store the custom files persistently:

$ sudo docker run -p 80:80 --link some-mysql:mysql  -v /var/www:/var/www/html --name docker-wordpress -d wordpress

The problem is that even when exactly replicating the ownership and priviledges on local files in /var/www:

$ sudo chown -R www-data:www-data /var/www
$ sudo find /var/www/ -type d -exec chmod 755 {} \;
$ sudo find /var/www/ -type f -exec chmod 644 {} \;

I am still getting an error of this kind, when running Wordpress inside the container:

Could not create directory

How to set the privileges properly to make sure Wordpress is able to write into the mounted Docker volume?

Answer 1

Looking at your error message i come to the conclusion that you are trying to install a plugin or update wordpress itself

This issue is slightly tricky to figure out.

executing chown -R www-data:www-data /var/www to set correct user:group permissions should technically solve it, however ..

On a new wordpress install the upload & plugins folder does not yet exist and therefore when installer trying to create a plugins/subfolder it will throw the error.

How to Fix Wordpress / Docker Plugin install Permission issue

Fixing this issue is however quite easy once grasping it.

Option A

in your .Docker file add following towards the very end but before any [CMD] command.

RUN mkdir /var/www/html/wp-content/plugins
RUN mkdir /var/www/html/wp-content/uploads
RUN chown -R www-data:www-data /var/www
RUN find /var/www/ -type d -exec chmod 0755 {} \;
RUN find /var/www/ -type f -exec chmod 644 {} \;

Option B

ssh in to your docker container
docker exec -it <container_name> /bin/bash

If you don't know the container name find it with
docker ps

Simply run same commands as in example above
$ mkdir /var/www/html/wp-content/plugins
$ mkdir /var/www/html/wp-content/uploads
$ chown -R www-data:www-data /var/www
$ find /var/www/ -type d -exec chmod 0755 {} \;
$ find /var/www/ -type f -exec chmod 644 {} \;