Add a new mechanism for requeuing a key.

[mattmoor]

Changes

This is modeled after some of the semantics available in controller-runtime's Result type, which allows reconcilers to indicate a desire to reprocess a key either immediately or after a delay.

I worked around our lack of this when I reworked Tekton's timeout handling logic by exposing a "snooze" function to the Reconciler that wrapped EnqueueAfter, but this feels like a cleaner API for folks to use in general, and is consistent with our NewPermanentError and NewSkipKey functions in terms of influencing the queuing behaviors in our reconcilers via wrapped errors.

You can see some discussion of this here: https://knative.slack.com/archives/CA4DNJ9A4/p1627524921161100

/kind enhancement

Release Note

Introduce a way for Knative-style controllers to requeue keys by returning a wrapped error from Reconcile[Kind].  See NewRequeue{Immediately,After} for more details.

Docs

Shouldn't have user-facing docs impact.

[vaikas]

UT failed with:

--- FAIL: TestAdmissionValidResponseForResource (0.21s)
    logger.go:130: 2021-07-29T21:15:09.052Z	ERROR	webhook/webhook.go:196	failed to fetch secret	{"error": "secret \"webhook-certs\" not found"}
    admission_integration_test.go:139: Failed to get response Get "https://0.0.0.0:43137/bazinga": remote error: tls: unrecognized name
    admission_integration_test.go:176: Admit was called before informers had synced.
    logger.go:130: 2021-07-29T21:15:09.052Z	INFO	webhook/webhook.go:235	Starting to fail readiness probes...
    ```

[mattmoor]

I haven't touched that and can't rerun it because I'm not an editor.

[vaikas]

Yeah, I'm rerunning them :)
/lgtm
/approve
/hold

Just adding a hold so the other folks from the thread have a chance to take a look. If they don't have concerns, I'll remove the hold tmw morning.
@markusthoemmes

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mattmoor, vaikas

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[codecov]

Codecov Report

Merging #2201 (083056d) into main (889b567) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2201      +/-   ##
==========================================
+ Coverage   65.98%   66.04%   +0.05%     
==========================================
  Files         220      220              
  Lines        9207     9220      +13     
==========================================
+ Hits         6075     6089      +14     
+ Misses       2861     2860       -1     
  Partials      271      271              

Impacted Files	Coverage Δ
controller/controller.go	87.59% <100.00%> (+1.03%)	⬆️
test/gcs/mock/mock.go	91.39% <0.00%> (ø)

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[vaikas]

/unhold

[mattmoor]

Looks like we want codegen to not emit an event for these too, so I'll have a small follow-up shortly.