Whether/how to cache action on self-hosted runner?

[TingluoHuang]

Then runner download the action's tarball/zipball via github api, unzip to disk under _work/_actions/<repo>/<ref>.

The runner won't re-download any action if it's already on disk.

I think we need to re-check this logic before self-hosted runner GA.

Ex:

- uses: actions/checkout@v1

action.yml on disk: _work/_actions/actions/checkout/v1/action.yml

Since action author can repoint their v1 tag to the latest v1 version, ex: v1.0.0 to v1.0.1, the current action download/cache logic will prevent user using self-hosted runner to get latest version on a version channel.

[bryanmacfarlane]

@ericsciple - we have two choices (1) resolve that ref and cache with the immutable ref or (2) don't cache the action and clear the action cache on the start of a job (hosted wouldn't pay cleanup cost).

When we discussed this awhile ago and launch wasn't resolving, we said it would be done runner side. It sounds like that wasn't done. We should ideally do that but fall back on #2 if that's not practical at this point.

@ericsciple - this is higher priority than checkout v2

[ericsciple]

I'm planning to clear the cache on job setup. We can add caching later.

[thboop]

Can we file an issue for caching and link this discussion so we can track it

[ericsciple]

@thboop ? this is an issue for caching

[ericsciple]

Closing this issue since the fix is in for self hosted runners. We can open a new issue for tracking later if we want to further enhance this.