Fixed method for checking cache-hit

[schneider10]

When checking cache-hit, this action will return an empty string on no hit, not 'false'. Therefore the correct method is to now check for !=true (see: https://github.com/actions/cache#Skipping-steps-based-on-cache-hit)

Why:

This doc is out of date or sharing incorrect info for the latest cache action.

What's being changed:

The documented method to check for a cache hit.

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[github-actions]

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Source	Preview	Production	What Changed
actions/using-workflows/caching-dependencies-to-speed-up-workflows.md	fpt ghec ghes@ 3.6 3.5	fpt ghec ghes@ 3.6 3.5

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[janiceilene]

@schneider10 Thanks so much for opening a PR! I'll get this triaged for review ⚡

[github-actions]

Thanks for opening a pull request! We've triaged this issue for technical review by a subject matter expert 👀

[lucascosti]

When checking cache-hit, this action will return an empty string on no hit, not 'false'.

👋 @N-Usha @bishal-pdMSFT Could you have a look at this and see if it might be a bug in the cache action? I've replicated the behavior here (with debug logging on).

In the action's code, it does look like a false value should be set for the output for a cache miss, and there does seem to be a test for this in the repo too.

[N-Usha]

Yes @lucascosti , the doc may need an update.. Including @aparna-ravindra who's verifying this from the code.

[aparna-ravindra]

In the action's code, it does look like a false value should be set for the output for a cache miss, and there does seem to be a test for this in the repo too.

@lucascosti, Unfortunately, the method in the test case you referred is not used in the action. The value for cache-hit is set to false in three cases:

1. Cache feature is not available (here).
2. If there was a cache restored - but on one of the restore-keys and not the primary key (here)
3. Any unhandled exception (here).

However, if no cache was restored (either on the primary key or the restore-keys), then the cache-hit output value is not set.
Therefore, the right way to test is to check for cache-hit != true as we see in the examples here

[lucascosti]

@lucascosti, Unfortunately, the method in the test case you referred is not used in the action. The value for cache-hit is set to false in three cases:

Thanks a lot for confirming this, @aparna-ravindra! 🙇‍♂️ My next question (possibly more for @N-Usha): is this behavior deliberate? If cache-hit is a boolean for determining if a cache hit on key happens, shouldn't it return false for any situation where there wasn't a cache hit on key?

I guess I'm trying to think of a case where returning a null value for when no cache was restored would be the desired/expected outcome. 🙃 I would have expected a null value returned for situations 1. (Cache feature is not available) and 3. (Unhandled exception) in the post above.

If it is deliberate, I'll take care of getting the docs updated (e.g. this section will also need updating) 👍

[aparna-ravindra]

Given that there are two possible values (null and false) that indicate cache-miss, checking for cache-hit != true will address both cases. Hence, I vote for updating the doc and thereby keeping it consistent with the example in the actions/cache public repository as well.

[github-actions]

This is a gentle bump for the docs team that this PR is waiting for technical review.

[jsoref]

Sounds like this is related to actions/cache#717 / actions/cache#661 (comment)

[github-actions]

This is a gentle bump for the docs team that this PR is waiting for technical review.

[aparna-ravindra]

@lucascosti Please feel free to ping if you need any more inputs from me.

[aparna-ravindra]

@lucascosti ,
we have a couple more requests (like this one) asking for doc update. How do we go about triaging this PR?

[lucascosti]

@lucascosti , we have a couple more requests (like this one) asking for doc update. How do we go about triaging this PR?

Sorry, @aparna-ravindra; I've been on some extended leave and this one slipped through the cracks. I'll get this reviewed and merged. 👍

[lucascosti]

Although being able to match on a cache hit on a false result would also be ideal, these changes more accurately describe the action's current behavior. 👍

[github-actions]

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[bchen1029]

@lucascosti this PR help setting cache hit on false when no hit. I think this is ideal solution as you do. Could you help check this PR actions/cache#876 if you're free? really appreciate!

[lucascosti]

Sorry, @bchen1029; the Actions engineering team will have to review those changes; I'm a docs writer and defer to them for any functionality changes.