Allow to set prefix for S3 storage

[Andrei Baidarov]

We use the same s3 bucket for buildbuddy and bazel-remote. The latter allows to specify prefix via config, the former doesn't. It makes it hard to navigate bucket since the root is polluted and also to specify different lifecycle policies for cache and buildbuddy reports.

Basically, we want this kind of structure:

cache/
   ac/
   cas.v/
buildbuddy/
   24971223-462c-4a5d-85e7-3c6f8c50f0a6/
   24989c17-ab53-4744-ace6-d76ddda9d720/
   ...

[Son Luong Ngoc]

Hey @tIGO, is it possible if you could test #3597 out?

[Son Luong Ngoc]

@tIGO FYI this feature would be in the next release that is coming out today.

[Brandon Duffany]

@tIGO do I understand correctly that you're using BuildBuddy as bes_backend only, and bazel-remote as remote_cache?

If so, I think we also need to support prefixes for the S3-backed blobstore - #3597 adds a prefix for S3 cache but not blobstore.

[Son Luong Ngoc]

We also implemented prefix support for the Build Event Storage (blob storage) in #3620.

This should be included in our weekly release next week. 🙇

[Andrei Baidarov]

Sorry for late response, I could try new version next week

@tIGO do I understand correctly that you're using BuildBuddy as bes_backend only, and bazel-remote as remote_cache?

That's correct

[Andrei Baidarov]

It works, thanks