Reading from arbitrary refs through proxy

[tazjin]

It would be quite useful to be able to read and filter arbitrary refs through josh-proxy. For example, Gerrit changes become available with refs like refs/changes/96/8096/21 and at TVL we have revision numbers at refs like refs/r/1337.

This would make it possible to expand ref-based versioning schemes (in our case, monotonically increasing integers) to filtered views and workspaces, or filter in-progress changes for test flows.

If this is in fact already possible, then consider the issue to be about documenting what syntax allows it :)

I've looked into this a little bit but am not familiar enough with the codebase to find the right spot to look. f1c8188 pointed me towards the apply_view_to_branch function, but that has since been refactored to elsewhere and I haven't found it yet

[christian-schilling]

This is a pretty common, already covered use case:
You can use an URL like https://server/repo.git@refs/r/1337:filter.git
Instead of @ you can use ^ (useful in some contexts) and instead of a ref you can also use a sha (of the canonical history) to specify what revision to filter.
See https://github.com/josh-project/josh/blob/master/tests/proxy/clone_sha.t

The resulting repo will have HEAD pointing to the filtered version of the specified rev.

[tazjin]

Thanks, that seems to work fine with the Gerrit change refs (which are the most important!). I'll see if I can come up with a docs change to make that easier to find.

However, I can't get that to work with our refs/r/... refs. We're currently working on upgrading our josh from a one year old version (time flies ...) to the current HEAD, and I'm actually seeing different behaviour on the two versions. The old one seems to ignore the refs/r/$n and just clones HEAD, the new one clones an empty repository.

Will spend more time investigating that later, for now I'm focusing on a different issue.

[deliciouslytyped]

I ran into not finding documentation on this, though I eventually found this issue.
I also ran into a problem of cloning empty repositories, but this is unrelated. I was trying to do the following, and the issue was the leading slash in the file path:
git clone http://localhost:4002/owner/project.git@refs/heads/develop::/infra/containers/DEPLOYMENT.git