Regression when no files/folders match path

In cache@v1, the step would fail to create the cache:

Post job cleanup.
/bin/tar -cz -f /home/runner/work/_temp/2a248b52-7c16-40d2-99f3-7385c4e6783a/cache.tgz -C /home/runner/.nuget/packages .
/bin/tar: /home/runner/.nuget/packages: Cannot open: No such file or directory
/bin/tar: Error is not recoverable: exiting now
[warning]Tar failed with error: The process '/bin/tar' failed with exit code 2

But in cache@v2, it creates an empty tar file:

Post job cleanup.
/bin/tar --use-compress-program zstd -T0 -cf cache.tzst -P -C /home/runner/work/cache-test/cache-test --files-from manifest.txt
Cache saved successfully

Which then results in extracting the empty tar:

Run actions/cache@v2
Cache Size: ~0 MB (22 B)
/bin/tar --use-compress-program zstd -d -xf /home/runner/work/_temp/f096b41b-1e38-4cd8-a7be-ead81367a21b/cache.tzst -P -C /home/runner/work/cache-test/cache-test
Cache restored from key: Linux-nuget--v2

Also note that when there are no matches for hashFiles, it fills in with an empty string. I believe it used to fail with an error when hashFiles failed to match anything.

[brandur]

Sorry for the drive by, but wanted to give this one a light +1.

Upgrading to cache@v2 caused my build to fail, but in a fairly non-obvious way. Based on the Cache Size: ~0 MB (22 B) message (and thanks to this issue!), I was able to localize it a problem with the cache not being populated with anything, but even right now, it’s not clear to me why that’s the case — I double-, triple-, and quadruple-checked my paths, and there’s nothing obviously wrong.

Of course this is still suggestive of a problem on my end, but this would have been a lot faster to diagnose and debug if the cache action complained loudly if it determined an input path did not exist.

[bishal-pdMSFT]

Closing. Re-open with more context if this is still an issue.