Track channel and user agent in logins

[ianb]

We want to distinguish pre-release users (i.e., Nightly and Beta users) from release Firefox users. Right now we're not saving enough in the device table to know the difference.

If we can get the channel information and add it to the login/register call that should be sufficient. Getting the User-Agent wouldn't be as helpful, as you have to match up dates to determine the channel based on the User-Agent. But we could consider User-Agent, as it could be done server-only.

We might want to consider copying the channel information to the shot (data) table on shot creation, so we track which channel the user was using at the moment they uploaded.

[chenba]

Depends on https://bugzilla.mozilla.org/show_bug.cgi?id=1386076

[chenba]

If we can access prefs with an experiment, which is currently discussed in #4800, then we can grab the channel from the prefs as well.

[ianb]

It might be easiest to just use release JSON files on the server: https://wiki.mozilla.org/Release_Management/Product_details

Specifically this file will identify when we should start treating a version as a production release, and this file gives some additional information. My only concern here is that if the file isn't updated very promptly (or ahead of a release) we might be unaware of a version update.

I think a combination of this file, the actual Firefox version, and the date of creation, will give us enough information. We'll want to leave out the last couple days from the report, just because of the possibility of a slow update on a JSON file. It would be great to get the channel from the add-on as well, but... we can do both, if we want to try to move forward on both fronts.

[clouserw]

Getting channel from the add-on could be a stretch/enhancement. Grabbing the product details seems easiest and most likely to get done this quarter. We need to get this channel stuff hooked up to finish the Watchdog integration which we're on the hook for this quarter.

[chenba]

AppConstants.MOZ_UPDATE_CHANNEL is available through an experiment API (https://github.com/mozilla-services/screenshots/blob/master/addon/webextension/experiments/screenshots/api.js#L29). Are not we not using that because we want to do everything server side?

[jaredhirsch]

That API will be available as of Firefox 64, which hits release in December 2018.