The core of Chassis is designed around you having everything needed for your site-specific code in the content/ directory. This includes project-specific configuration (we load content/config.php in during wp-config.php loading) and your plugins and themes. This is designed such that you can keep your site self-contained in a separate repository, including API keys and such.

We also load 4 configuration files, allowing you to store project-specific configuration while still allowing overriding:

  • project/content/config.local.yaml - project-specific overrides
  • project/content/config.yaml - project-specific defaults
  • project/config.local.yaml - global overrides
  • project/config.yaml - global defaults

This allows you to (e.g.) enable multisite for the entire project, while allowing specific users to override the hostname if it conflicts with existing projects.

Changing your Chassis box is a quick two-step process:

  1. Change the relevant configuration file as above and save
  2. Run vagrant provision

vagrant provision tells Vagrant to update the box with your new settings, and should take care of updating everything internally.


WordPress developers will often require customisation of optional constants that are defined in wp-config.php.

We discourage editing wp-config.php in Chassis as we have an optional php file local-config.php which can contain custom constants and overrides for WordPress.

If local-config.php exists it will be loaded before wp-config.php so any constants that you define in local-config.php will be the defaults.

PHP Version

Key: php

PHP 7.0 is included with Chassis by default, plus we register the additional repositories for the other versions. We don’t download them all automatically, to avoid extra download times, but switching is still pretty fast as we pre-register the APT repositories.

To switch to 5.3 for example:

  1. Add php: 5.3
  2. Run vagrant provision

You can use either a two-part version (5.3) or a three-part version (5.3.1) if you want to pick specifc versions. We support any version between 5.3.0 and 5.6.x.


There are a few known issues on Windows with PHP 5.4.

WordPress Directory

Key: wpdir

Chassis also includes the latest-released version of WordPress by default, but we also allow swapping this out completely for users who want the flexibility. Our built-in version follows the pattern laid out by WordPress Skeleton, however you can change this easily if you want.

For example, to swap out the current version of WordPress for the latest development version:

  1. Clone to wp-trunk/
  2. Add wpdir: wp-trunk to your config.local.yaml
  3. Run vagrant provision

We want to make this as flexible as possible, without forcing you to run through any of these steps if you don’t need to.


If you’re forking Chassis and want to maintain it yourself, you’ll need to keep your copy of WP up-to-date as well. We recommend merging Chassis changes back to your forked version, but you can also do it yourself:

# To update to WP 4.2.1, e.g:
bash puppet/ 4.2.1


Key: multisite

Chassis includes built-in support for WordPress multisite, with both subdirectories and subdomains. This is turned off by default, but can be turned on easily.

  • For multisite in subdirectories, set multisite: Yes
  • For multisite on subdomains, set multisite: subdomains

Then just reprovision.

When multisite is turned on, Chassis will set up WordPress in “subdirectory” mode; that is, sites will be created under the root, but using the same domain. A site called “test” would be created at /test/, for example.

Subdirectory mode is great, but subdomain mode is even better. With subdomains, a site called “test” would be available at test.vagrant.local. This is one of the most common ways that multisite is set up, since it also means you’re separating your sites more cleanly. Simply set the value to subdomains and reprovision. Once this is done, subdomains will work automatically in your browser. Create and remove sites at will, and Chassis will ensure it just works.


Changing from multisite back to single site requires creating the box from scratch, using vagrant destroy before running vagrant up. This is due to WordPress’ inability to switch back.

This will wipe your database, so make sure you export any sites’ content that you need (via the WordPress exporter).

Default Admin

Key: admin

When you first set up your site, Chassis will install WordPress and create the default admin user for you. By default, this user is set up as admin with the password password to keep it simple for local development.

To change this, simply set the admin configuration option to different values, like so:

    user: admin
    password: password


You must include all lines shown above (albeit with your custom configuration), even if you’re not changing from the default.

Changing the default admin requires creating the box from scratch, using vagrant destroy before running vagrant up.

Note also that the indentation must be done with spaces, not tabs in YAML configuration.

Database Configuration

Key: database

Similar to the admin user configuration, you can also override the default MySQL username and password:

    name: wordpress
    user: wordpress
    password: vagrantpassword

(Again, don’t forget to include all lines, and use spaces for indentation.)

Custom Host Names

Key: hosts

By default, Chassis will set up vagrant.local as your main domain. If you’d like to change this, you can override the hosts configuration item. Note that this is a list, so it should have list items in the following format:

    - vagrant.local
    - althost.local

The first host here will be set as the main host for the box and in WordPress. Subsequent hosts will be set as aliases of the main domain using nginx, and may be redirected by WordPress depending on your configuration or plugins.


Domains ending in something other than .local won’t have DNS set up for them automatically, so make sure to add these to your hosts file on your computer (not inside the virtual machine).

If you need to find out the IP address of your machine, run vagrant ssh to connect, then inside the box run ifconfig eth1 and look for the line starting with inet addr:.

IP Address

Key: ip

Chassis picks an IP address for your box automatically, using DHCP. If you’d prefer a static IP, you can specify this here with ip:

(Typically, this should be in the private routing range; either 192.168.x.x or 10.x.x.x)

APT Mirror

Key: apt_mirror

To speed up package installation, Chassis can tell Ubuntu to use the closest mirror to you, rather than the main mirror ( This typically speeds up installation by decreasing latency, however it may cause slowness with some slower or badly-behaving mirrors.

You can tell Chassis to do this by setting apt_mirror: Yes

If you have a specific mirror you’d like to use, you can set this as the value instead, such as:


Synced Folders

Key: synced_folders

By default Chassis syncs the php and nginx logs for you onto your local machine in the logs folder.

You may want to keep your themes and projects along-side Chassis, instead of inside it. You’ll need to tell Chassis about these external directories, as it won’t know how to map them. You can tell Chassis to map some external directories into the generated VM like so:

  a/host/directory: a/vm/directory
  "this:ones:got:colons": another/vm/directory


Key: paths

If you’re transplanting Chassis into an existing project, you can manually set some paths manually. These can be set to absolute paths, or relative paths.

   base: .
   wp: wordpress
   content: wordpress/wp-content


Key: plugins

If you’re using plugins from the repository you can add them in a list using the plugins slug. These will be downloaded, installed and activated for you.

To find the slug just copy and paste the plugins slug from your browsers. For example the URL for Query Monitor is which makes the slug query-monitor.

   - query-monitor
   - user-switching


Key: themes

If you’re using themes from the repository you can add them in a list using the themes slug. These will be downloaded for you. The last theme in the list will be the theme that is activated for your site.

To find the slug just copy and paste the plugins slug from your browsers. For example the URL for Twenty Sixteen is which makes the slug twentysixteen.

   - twentyfifteen
   - twentysixteen


Key: extensions

You can enable official Chassis extensions and third party extensions by listing their repo name in the extensions section:

   - Chassis/Tester
   - javorszky/chassis-openssl

Machine Customisations

The underlying virtual machine managed by Vagrant can be customised, but depends on which provider you are using.


Key: virtualbox

When using VirtualBox, you can customise how much memory (in megabytes) and how many virtual CPUs will be assigned to the machine. The default values for both (null) are to use the VirtualBox defaults (384 MB of RAM, and 2 vCPUs).

   memory: null
   cpus: null