I'm creating a local page for this as it was quite difficult to install so I want some of my own notes for future reference. The main page for the extension is at MW:Extension:VisualEditor.
First download and unpack a snapshot for the extension corresponding to the wiki version as usual, then install nodejs with apt, but if your repo has an older version than 0.8, then remove it and install from NodeSource using the following commands (see this for details).
Now install the paisoid package via apt (see MW:Parsoid/Setup for more detail). First add the key for the deb,
Then add the following to you /etc/apt/sources.list (only amd64 is available),
Then udpate and install it,
Edit the parsoid configuration (/etc/mediawiki/parsoid/settings.js) adding a line for each wiki in the wikia that will be using the editor, e.g.
You may also like to lock down the parsoid daemon so it can only be accessed from the local host which you can do by editing /etc/default/parsoid and changing the INTERFACE setting from 0.0.0.0 to 127.0.0.1.
Restart the parsoid daemon and then test that you can read a page as follows (note the wiki ID matching the setting above):
Include the extension and its settings in the wiki's LocalSettings.php, e.g.
If you're running a private wiki (no public editing allowed) then you'll need to also set the following, but note that this means your cookie data is being sent over HTTP, so make sure you only do this if the parsoid daemon is on the localhost.
If you're system is running an SSD and you've gone through the SSD Optimisation checklist then you'll need to edit the start case in the /etc/init.d/parsoid file and have it create the /var/log/parsoid directory owned by parsoid. See the Nginx and MariaDB examples on that page for details.