Talk:Features/Desktop/Add-on hotfix

I think the goal of this feature should be to make it possible to automatically download "hotfix" extensions to Firefox to correct problems that would otherwise necessitate chemspills. I don't think we should constrain ourselves to the current simplest solution of shipping a dummy add-on with the release. I think this is a bad solution for the following reasons:

• We'd have to implement a mechanism for hiding this extension from users. Whatever mechanism we use would likely be exploitable by other add-ons unless we put a bunch of checks in place that would likely be complicated and expensive.
• Users would still be able to uninstall the extension by removing it from the filesystem
• Updates to the extension aren't controlled by the app update controls, it seems like we should only be downloading a hotfix if the user has agreed to automatic app updates

Instead I think we should implement a small new piece of code into Firefox:

Periodically the add-ons manager will ping an update URL to check for new versions of add-ons to install. If one is indicated to be available then it downloads and installs it.

This has the following benefits:

• The amount of code to implement this is trivial, it still reuses the add-ons manager code for update checks, downloads and installs. There is likely less new code here than there would be for hiding/checking the dummy add-on
• We could ship multiple hotfixes. While the update check would have to check for a specific ID, the downloaded add-on could have any unique ID allowing us to potentially install many hotfixes at the same time before the next update
• We could actively expose the hotfixes to the user as a new category in the add-ons manager if we wanted allowing users to remove hotfixes they didn't want
• We could do prompting after a hotfix is downloaded asking a user to restart unlike for other add-ons
• The code doing the automated ping could observe the app update prefs correctly, it could even be in the update service code if that made sense.

Mossop 14:53, 3 October 2011 (PDT)

One additional benefit is that with the dummy add-on if we just wanted to install a one-time fix like a pref change then we'd have to make the downloaded add-on more clever than it needs, prefs to make sure it only ran once etc. With the multi-hotfix case the add-on can just uninstall itself afterwards.

A disadvantage I've just realised is that we'd have to do something a little more to make sure Firefox didn't try to download the same hotfix over and over again.

Mossop 12:36, 4 October 2011 (PDT)