Support several downloader configs

[pilkjaer]

Description of the problem / feature request:

Currently --experimental_downloader_config flag only supports one value. It's not possible to provide several files. Providing several files doesn't result in any error but only one file is being used.

Feature requests: what underlying problem are you trying to solve with this feature?

We use Bazel in several projects and we would like to be able to provide one downloader_config centrally and then for each project to be able to provide their own additional downloader_config file when needed.

What operating system are you running Bazel on?

RHEL7

What's the output of bazel info release?

release 4.0.0

What's the output of git remote get-url origin ; git rev-parse master ; git rev-parse HEAD ?

https://github.com/bazelbuild/bazel.git
a3c52a7
6b33bdb

Have you found anything relevant by searching the web?

No. Current possible solution is having some kind of script to combine downloader config files prior bazel build which is not optimal.

Any other information, logs, or outputs that you want to share?

We can try to make an implementation and submit it as pull request if idea of having several downloader configs is OK with you.

[pilkjaer]

Feature request is related to 9d29464 that introduces feature.

[Wyverald]

Seems like a reasonable change (making it possible to specify the flag multiple times). Happy to accept PRs.

cc @shs96c

[github-actions]

Thank you for contributing to the Bazel repository! This issue has been marked as stale since it has not had any activity in the last 1+ years. It will be closed in the next 14 days unless any other activity occurs or one of the following labels is added: "not stale", "awaiting-bazeler". Please reach out to the triage team (@bazelbuild/triage) if you think this issue is still relevant or you are interested in getting the issue resolved.

[github-actions]

This issue has been automatically closed due to inactivity. If you're still interested in pursuing this, please reach out to the triage team (@bazelbuild/triage). Thanks!

[pilkjaer]

@bazelbuild/triage We are still interested in this feature and would like to see it implemented.

[faximan]

+1 to this FR.

Another option could be to allow one config to include another.