use 'cache' in composite action: Failed to save: Unable to reserve cache with key

[colemickens]

I'm not really sure what's going.

Ever since I moved my cache restore+save into a composite action, the save fails every single time:

Run actions/cache/save@v3
  with:
    path: /tmp/cache
    key: nixcfg-hm-1
    enableCrossOsArchive: false
  env:
    NIXCFG_CI_BRANCH: nixcfg--
/usr/bin/tar --posix -cf cache.tzst --exclude cache.tzst -P -C /home/runner/work/nixcfg/nixcfg --files-from manifest.txt --use-compress-program zstdmt
Failed to save: Unable to reserve cache with key nixcfg-hm-1, another job may be creating this cache. More details: Cache already exists. Scope: refs/heads/main, Key: nixcfg-hm-1, Version: 2e3304f2b0fc224b01601463e4efe06a95c58b14257353eeb31e37898c172bea
Warning: Cache save failed.

[colemickens]

Well, I reved the cache key and ran it again and it saved the cache... and then failed to restore it on subsequent run, despite the fact you can see the cache key is the same...

+ date
Thu Jun  8 03:32:28 UTC 2023
Run actions/cache/save@v3
/usr/bin/tar --posix -cf cache.tzst --exclude cache.tzst -P -C /home/runner/work/nixcfg/nixcfg --files-from manifest.txt --use-compress-program zstdmt
Cache Size: ~273 MB (286535608 B)
Cache saved successfully
Cache saved with key: nixcfg-hm-2

subsequent run:

Run actions/cache/restore@v3

Cache not found for input keys: nixcfg-hm-2

Unless canceling a run invalidates a previous cache upload, which would be unfortunate... I already have the ability to save based on step conditions, so I'd really rather it didn't. Or maybe caching is optimistic at best? Not sure.

[colemickens]

And now back to complaints about not being able to reserve the cache.

So:

• cache error
• change key
• persists
• fails to restore
• then, in the SAME WORKFLOW RUN, it fails to persist with a complaint about the cache key being reserved

Failed to save: Unable to reserve cache with key nixcfg-hm-2, another job may be creating this cache. More details: Cache already exists. Scope: refs/heads/main, Key: nixcfg-hm-2, Version: 9e02f6448824ce56c58e934cb740949d94970ffb76a9156cebc26bf241acf5dc

[colemickens]

And now another run again says the cache key isn't there.

Is there some reason that it would tell me it saved the cache, but then be in this stuck state?

[colemickens]

It feels like what's happening is:

1. Workflow gets to "cache save" step, it is successful.
2. The workflow continues running, and I stop it because I'm debugging/working on it.
3. The saved cache is invalidated, but the reservation for it isn't invalidated.

Is this possible? It seems to match my symptoms anyway.

[colemickens]

This just flat out seems broken. I can very clearly see a cache with that key in the Actions Cache Management UI and yet it keeps:

1. Telling me there's no cache with that key.
2. Telling me it can't save the cache because another job is (it isn't).

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[github-actions[bot]]

This issue was closed because it has been inactive for 5 days since being marked as stale.

[colemickens]

lol.