soledad penadés

A couple of days ago Tom Dale published a post detailing the issues the Ember team are having with getting the Ember Inspector add-on reviewed and approved.

It left me wondering if there would not be any other way to publish add-ons on a different site. Knowing Mozilla, it would be very weird if add-ons were "hardcoded" and tied only and exclusively to a mozilla.org property.

So I asked. And I got answers. The answer is: yes, you can publish your add-on anywhere, and yes your add-on can get the benefit of automatic updates too. There are a couple of things you need to do, but it is entirely feasible.

First, you need to host your add-on using HTTPS or "all sorts of problems will happen".

Second: the manifest inside the add-on must have a field pointing to an update file. This field is called the updateURL, and here's an example from the very own Firefox OS simulator source code. Snippet for posterity:

<em:updateURL>@ADDON_UPDATE_URL@</em:updateURL>

You could have some sort of "template" file to generate the actual manifest at build time--you already have some build step that creates the xpi file for the add-on anyway, so it's a matter of creating this little file.

And you also have to create the update.rdf file which is what the browser will be looking at somewhat periodically to see if there's an update. Think of that as an RSS feed that the browser subscribes to ;-)

Here's, again, an example of how an update.rdf file looks like, taken from one of the Firefox OS simulators:

<?xml version="1.0" encoding="utf-8"?>
<RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:em="http://www.mozilla.org/2004/em-rdf#">
<Description about="urn:mozilla:extension:fxos_2_2_simulator@mozilla.org">
<em:updates>
<Seq><li>
<Description>
  <em:version>2.2.20141123</em:version>
  <em:targetApplication>
  <Description>
    <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
    <em:minVersion>19.0</em:minVersion>
    <em:maxVersion>40.*</em:maxVersion>
    <em:updateLink>https://ftp.mozilla.org/pub/mozilla.org/labs/fxos-simulator/2.2/mac64/fxos-simulator-2.2.20141123-mac64.xpi</em:updateLink>
  </Description>
  </em:targetApplication>
</Description>
</li></Seq>
</em:updates>
</Description>
</RDF>

And again this file could be generated at build time and perhaps checked in the repo along with the xpi file containing the add-on itself, and served using github pages which do allow serving https.

The Firefox OS simulators are a fine example of add-ons that you can install, get automatic updates for, and are not hosted in addons.mozilla.org.

Hope this helps.

Thanks to Ryan Stinnett and Alex Poirot for their information-rich answers to my questions--they made this post possible!