1438960 - Disable RecipeRunner in Firefox headless mode

Status: NEW

(Firefox :: Normandy Client, enhancement, P3)

Description

[Robert Helmer [:rhelmer]]

Firefox has a "headless" mode that runs without a display:
https://developer.mozilla.org/en-US/Firefox/Headless_mode

We almost certainly never want to run studies on users in this configuration.

Perhaps there should be a filter (default off) on the off chance that we do want to include these users. Or, we should just exclude them from matching entirely.

Comment 1

[Michael Cooper [:mythmon]]

I think that being able to target headless browsers isn't useful, and it would be technically weird given the way we currently handle targeting. Specifically, things not mentioned explicitly in targeting filters can't affect the result. I don't think changing this is a good idea.

I'd be happy to add "is in headless mode" to the current list of reasons that we don't run recipes. We have a method to do this based on several things already, such as policy engine and prefs, `RecipeRunner.checkPrefs` [0]. We'll likely want to change the name of that method from `checkPrefs` to something more appropriate, since it is checking two things that aren't prefs now. We'll need to figure out how to detect headless mode. Besides that, this should be fairly easy to do. This would make a good first bug for the normandy client.

[0]: https://hg.mozilla.org/mozilla-central/file/928f0f09172f/browser/extensions/shield-recipe-client/lib/RecipeRunner.jsm#l137

Comment 2

[Bianca Danforth [:bdanforth]]

This method of detecting headless mode was suggested to me from folks in the #headless IRC channel when I was considering adding a check inside my study: `Cc["@mozilla.org/gfx/info;1"].getService(Ci.nsIGfxInfo).isHeadless` [0].

[0]: https://dxr.mozilla.org/mozilla-central/source/testing/marionette/doc/api/session.js.html#404