• By Matthew Ruffell
Channel Version Revision Published Runs on
latest/stable 0 0 08 Apr 2021
Ubuntu 18.04 Ubuntu 16.04
juju deploy wordpress
Show information


18.04 16.04


WordPress is a powerful blogging platform written in PHP. This charm aims to deploy WordPress in a fashion that will allow anyone to scale and grow out a single installation.


This charm is available in the Juju Charm Store, to deploy you'll need at a minimum: a cloud environment, a working Juju installation, and a successful bootstrap. Please refer to the Juju Getting Started documentation before continuing.

Once bootstrapped, deploy the MySQL charm then this WordPress charm:

juju deploy mysql
juju deploy wordpress

Add a relation between the two of them

juju add-relation wordpress mysql

Expose the WordPress installation

juju expose wordpress

Scaled Down Usage for Personal Use

If you're just looking to run a personal blog and want to save money you can run all of this on a single node, here's an entire single node installation from scratch:

juju bootstrap
juju deploy --to 0 wordpress
juju deploy --to 0 mysql
juju add-relation wordpress mysql 
juju expose wordpress

This will run everything on one node, however we still have the flexibility to grow horizontally. If your blog gets more traffic and you need to scale:

juju add-unit wordpress

Since we're omitting the --to command Juju will fire up a new dedicated machine for Wordpress and relate it. You can also remove-unit when the surge is over and go back to a cheaper one node set up.

Scale Out Usage

You can deploy a memcached server and relate it to your WordPress service to add memcache caching. This will automagically install WP-FFPC (regardless of your tuning settings) and configure it to cache rendered pages to the memcache server. In addition to this layer of caching, Nginx will pull directly from memcached bypassing PHP altogether. You could theoretically then turn off php-fpm on all of your servers and just have Nginx serve static content via memcached (though, you wouldn't be able to access the admin panel or any uncached pages - it's just a potential scenario).

juju deploy memcached
juju add-relation memcached wordpress

This setup will also synchronize the flushing of cache across all WordPress nodes, making it ideal to avoid stale caches.

Once the relation is set and the hooks have ran accordingly, you will need to manually save the settings for WP-FFPC. Everything will be configured, though. Just log in to the administrator Dashboard, and then click the link to the WP-FFPC Settings page displayed on the error at the top of the page. Finally, scroll down and click on the blue button which says Save Changes.

A small note, when using the Apache2 engine and memcache, all request will still be sent to WordPress via Apache where typical caching procedures will take place and wp-ffpc will render the memcached page.


This WordPress charm comes with several tuning levels designed to encompass the different styles in which this charm will be used.

A use case for each tuning style is outlined below:


The Bare configuration option is meant for those who wish to run the stock WordPress setup with no caching, no manipulation of data, and no additional scale out features enabled. This is ideal if you intend to install additional plugins to deal with coordinating WordPress units or simply wish to test drive WordPress as it is out of the box. This will still create a load-balancer when an additional unit is created, though everything else will be turned off (WordPress caching, APC OpCode caching, and NFS file sharing).

To run this WordPress charm under a bare tuning level execute the following:

juju set wordpress tuning=bare


When running in Single mode, this charm will make every attempt to provide a solid base for your WordPress install. By running in single the following will be enabled: Nginx microcache, APC OpCode caching, WordPress caching module, and the ability to sync files via NFS. While Single mode is designed to allow for scaling out, it's meant to only scale out for temporary relief; say in the event of a large traffic in-flux. It's recommended for long running scaled out versions that optimized is used. The removal of the file share speeds up the site and servers ensuring that the most efficient set up is provided.

To run this WordPress charm under a single tuning level execute the following:

juju set wordpress tuning=single


If you need to run WordPress on more than one instance constantly, or require scaling out and in on a regular basis, then Optimized is the recommended configuration. When you run WordPress under an Optimized tuning level, the ability to install, edit, and upgrade themes and plugins is disabled. By doing this the charm can drop the need for an NFS mount which is inefficient and serve everything from it's local disk. Everything else provided in Single level is available. In order to install or modify plugins with this setup you'll need to edit and commit them to a forked version of the charm in the files/wordpress/ directory.

To run this WordPress charm under an optimized tuning level execute the following:

juju set wordpress tuning=optimized

Handling wp-content

In order to allow for custom WordPress content within the Juju charm a separate configuration option exists for pointing to any Git or Bzr repository. To set the wp-content directive to a git repository, use one of the following formats making sure to replace items like host, path, and repo with their respective names:

juju set wordpress wp-content=https://host/path/repo.git


juju set wordpress wp-content=git://host/path/repo.git

If you wish to use a bzr repository, then apply one of the following schemes replacing items like host, username, path, and repo with their respective values:

For LaunchPad hosted repostiories:

juju set wordpress wp-content=lp:~username/path/repo

For other Bzr repositories:

juju set wordpress wp-content=bzr://host/path/repo


juju set wordpress wp-content=bzr+ssh://host/path/repo

Setting the wp-content option to an empty string ("") will result in no further updates being pulled from that repository; however, the last pull will remain on the system and will not be removed.


This option will create a directory _debug at the root of each unit (http://unit-address/_debug). In this directory are two scripts: info.php (/_debug/info.php) and apc.php (/_debug/apc.php). info.php is a simple phpinfo script that will outline exactly how the environment is configured. apc.php is the APC admin portal which provides APC caching details in addition to several administrative functions like clearing the APC cache. This should never be set to "yes" in production as it exposes detailed information about the environments and may provide a way for an intruder to DDoS the machine.

juju set wordpress debug=yes

to disable debugging:

juju set wordpress debug=no

The debugging is disabled by default.


By default the WordPress charm will install nginx and php-fpm to serve pages. In the event you do not wish to use nginx - for whatever reason - you can switch to Apache2. This will provide a near identical workflow as if you were using nginx with one key difference: memcached. In nginx, the cached pages are served from memcached prior to hitting the php contents, this isn't possible with apache2. As such memcached support still works, since it falls back to the WordPress caching engine, but it's not as robust. Otherwise, Apache2 will still perform balancing and everything else mentioned above. You can switch between engines at will with the following:

juju set wordpress engine=apache2

Then back to nginx:

juju set wordpress engine=nginx

Any other value will result in the default (nginx) being used.

Known Limitations and Issues

HP Cloud

At this time WordPress + Memcached don't work on HP Cloud's standard.xsmall. To get around this deploy the WordPress charm with the charm to at least a standard.small, to do this:

juju deploy --constraints "instance-type=standard.small" wordpress

This only is a problem when attempting to relate memcached to WordPress, otherwise an xsmall is okay though it's really not the best sized platform for running a stable WordPress install.

Single mode and the scale-out

If you're in Single mode and you want to/need to scale out, but you've been upgrading, modifying, and installing plugins + themes like a normal WordPress user on a normal install; you can still scale out but you'll need to deploy a shared-fs charm first. At the time of this writing only the NFS charm will work, but as more shared-fs charms come out (gluster, ceph, etc) that provide a shared-fs/mount interface those should all work as well. In this example we'll use NFS:

juju deploy nfs
juju add-relation nfs wordpress:nfs

By doing so, everything in the wp-contents directory is moved to this NFS mount and then shared to all future WordPress units. It's strongly recommended that you first deploy the nfs mount, then scale WordPress out. Failure to do so may result in data loss. Once nfs is deployed, running, and related you can scale out the WordPress unit using the following command:

juju add-unit wordpress

In the event you want more than one unit at a time (and do not wish to run the add-unit command multiple times) you can supply a -n number of units to add, so to add three more units:

juju add-unit -n3 wordpress

Memcached Issues

In order to have a working relation with memcached, you need to first set up your Wordpress blog, by creating your first user. If you try to relate memcached before, you will get a cache-relation-changed error on your instance.

Contact Information

WordPress Contact Information