title: Wordpress on Docker: Could not create directory on mounted volume
body: <p>Here is are the original files in the Wordpress Docker container on path <code>/var/www/html</code>:</p>
  
  <pre><code>$ 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
  </code></pre>
  
  <p>I am trying to start the Wordpress container with a mounted Docker volume to be able to store the custom files persistently:</p>
  
  <pre><code>$ sudo docker run -p 80:80 --link some-mysql:mysql  -v /var/www:/var/www/html --name docker-wordpress -d wordpress
  </code></pre>
  
  <p>The problem is that even when exactly replicating the ownership and priviledges on local files in <code>/var/www</code>:</p>
  
  <pre><code>$ 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 {} \;
  </code></pre>
  
  <p>I am still getting an error of this kind, when running Wordpress inside the container:</p>
  
  <blockquote>
    <p>Could not create directory</p>
  </blockquote>
  
  <p>How to set the privileges properly to make sure Wordpress is able to write into the mounted Docker volume?</p>