Do you want to cache accross builds, or only accross runs in one build? Be careful: * when you get the cache, properly set the saved timestamp, otherwise Make will never want to update it even if it should * be careful with the branches * should you also cache other downloaded stuff?

Re-purposing this bug to only cache the s3 tarball we use in taskcluster to warm the git clone (this is a no brainer and entirely within the docker container setup rather then in gaia) see https://bugzilla.mozilla.org/show_bug.cgi?id=1067626 for some more details on how TC actually does caching.

Greg you feel up for reviewing this? First place we are really using the cache... From my less then scientific measurement this saves 30s~ of overhead but more importantly it removes 1gig of network traffic (reducing traffic helps at higher capacity nodes)

Ah note that is PR is based on earlier work so see the second commit only.

Comment on attachment 8503728 [details] https://github.com/mozilla-b2g/gaia/pull/25059 r+ with just a couple of questions on GH to be clarified.

Now that I have had some time to think about I think the cache "resources" is the wrong name... (also this becomes a scoping problem I found out later) so I think renaming it to "gaia" is specific enough. Ideally we use one cache for all of gaia (or version the cache if we totally change what is stored in it)