Testing things in JOG is hard because it governs behaviour in artifact builds, but is itself filled with compiled components.

Jan-Erik did some hackery in his recent changes. I know I've done some fun things with --setpref telemetry.fog.artifact_build=true.

None of this is documented, and even if it were it isn't the easiest.

This bug is about

• Seeing how easy it's worth making "testing JOG" -- Generating the jogfile on demand, running with locally-built artifacts instead of an artifact build, etc.
• Documenting the process in either the dev testing docs or the dev JOG docs (and linking to it from the other)

Docs update incoming, tooling'll be a little more complicated.

To test JOG you need a jogfile that was generated against your tree. The way I currently do this is to swap out for an artifact build .mozconfig and then copy its jogfile.json to my fullbuild's objdr/dist/bin/ where JOG will find it, if I run with --setpref telemetry.fog.artifact_build=true.

These are the instructions that'll be in the docs, but it'd be much nicer if we could ./mach glean jogfile and have it output the jogfile for us, preferably in objdir/dist/bin. But it needs to consume all the metrics, tags, and pings files to do it (as well as have a decent understanding of the current command execution environment) so, though straightforward, I've decided that's too much effort to spend today.

Also, update the crate name for logging firefox_on_glean which I should've done
two years ago in bug 1765921.

https://hg.mozilla.org/mozilla-central/rev/05ec0d60628c

(deprioritizing now that docs are helping)