Allow to configure delay before controller exits

[theunrealgeek]

What this PR does / why we need it:

Today there is a hardcoded 10 second delay after nginx has quit before the controller exits when the pod is to be terminated:

ingress-nginx/cmd/nginx/main.go

Line 178 in 5f7656f

time.Sleep(10 * time.Second)

This was raised as an issue since it adds unnecessary delay to pod termination. This PR makes it configurable while keeping the current behavior as default.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation only

Which issue/s this PR fixes

#8095

How Has This Been Tested?

Tested in local dev environment by adding --post-shutdown-grace-period with various values and terminating the pod to see the new log message and the delay.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added tests to cover my changes.
• All new and existing tests passed.

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[rikatz]

/ok-to-test

[rikatz]

Suggested change

	klog.Infof(
	"Handled quit, delaying controller exit for %d seconds",
	delay,
	)
	klog.Infof("Handled quit, delaying controller exit for %d seconds", delay)

[rikatz]

/approve

Just fix the recommended commit, and once that's fixed and the test passes lgtm!

Thanks!

[rikatz]

/lgtm

I had a small nit that this change of handleSigterm is not required as the var postShutdownGradePEriod is from the same package but I'm fine with this as well. Maybe as a followup cleanup

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rikatz, theunrealgeek

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[theunrealgeek]

@rikatz

I had a small nit that this change of handleSigterm is not required as the var postShutdownGradePEriod is from the same package but I'm fine with this as well. Maybe as a followup cleanup

I actually tried to do it that way, but since flags were parsed into this conf variable:
https://github.com/theunrealgeek/ingress-nginx/blob/358d072c279bafa935709f7281d676478fbd7002/cmd/nginx/main.go#L61
I followed that path.

Now within handleSigterm, I have ngx *controller.NGINXController, unfortunately the config object cfg is not exposed from the controller package:

ingress-nginx/internal/ingress/controller/nginx.go

Line 209 in d16e0de

cfg *Configuration