✨Use correct context to cancel "list and watch" & wait for all informers to complete

[inteon]

This PR fixes this TODO item:

controller-runtime/pkg/cache/internal/informers_map.go

Lines 320 to 322 in b756161

	// TODO(vincepri): Wire the context in here and don't use TODO().
	// Can we use the context from the Get call?
	ctx := context.TODO()

It also make sure that all informers finish (using a sync.WaitGroup) before returning from the Start function.

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[alvaroaleman]

/hold

Looks good to me, thanks!

/cc @vincepri for a second set of eyes

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/hold

Looks good to me, thanks!

/cc @vincepri for a second set of eyes

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[inteon]

/retest

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/retest

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[alvaroaleman]

/ok-to-test
/retest

[vincepri]

At the top of this function, shouldn't we check first if we're stopped already before getting all the way down here and return an error?

If I got the flow right, this function would still return correctly even if the informermap has been stopped

[inteon]

Indeed, I still return correctly. I did this to make sure the behavior remained identical to before the change.

[vincepri]

We should probably return an error instead of treating it as a no-op, given that the code will silently fail

[inteon]

It won't fail silently, it will error here (identical to current behavior):

controller-runtime/pkg/cache/internal/informers_map.go

Line 266 in 45e7aa7

return started, nil, apierrors.NewTimeoutError(fmt.Sprintf("failed waiting for %T Informer to sync", obj), 0)

I think that in order to prevent making a breaking change, we should return a valid informer (that has not been started) from addInformerToMap.

There are multiple ways to get to that timeout error, eg. if the cache is terminated + all informers are terminated before cache.WaitForCacheSync returns true. Ideally, we figure out how to cancel this cache.WaitForCacheSync call when ip.ctx is canceled.

[vincepri]

That makes sense, although it sounds to me it might be a user error to add after Stop has been called. Could we mark this as a breaking change and return that error?

[inteon]

Ok, I'll need some more time to figure out how to reliably return an error. I agree that it would be useful to make a breaking change here.

[inteon]

/retest

[vincepri]

/approve
/lgtm
/hold cancel

Merging this now, the current set of changes look good. Let's follow-up for the next iteration to return an error

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alvaroaleman, inteon, vincepri

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