Add certs secret name read from env

[hhk7734]

Changes

• Add certificates k8s secret name read from environment variables

/kind enhancement

• I want to change secret name when I use knative operator.

Release Note

Docs

[knative-prow]

Welcome @hhk7734! It looks like this is your first PR to knative/pkg 🎉

[knative-prow]

Hi @hhk7734. Thanks for your PR.

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[dprotaso]

Is this a dupe of #2662 ?

[hhk7734]

Is this a dupe of #2662 ?

No. #2662 deals with the key of the secret.data and this deals with the secret.metadata.name.

[dprotaso]

We provide an option to change the secret name for look up here:

pkg/webhook/webhook.go

Lines 46 to 52 in 2fdd6bf

	// SecretName is the name of k8s secret that contains the webhook
	// server key/cert and corresponding CA cert that signed them. The
	// server key/cert are used to serve the webhook and the CA cert
	// is provided to k8s apiserver during admission controller
	// registration.
	// If no SecretName is provided, then the webhook serves without TLS.
	SecretName string

[hhk7734]

We provide an option to change the secret name for look up here:

I wanted to be able to set secret name as an environment variable when installing knative/operator.

previously, I submiited https://github.com/knative/operator/pull/1338/files. I was advised to modify knative/pkg code.
so I submitted this PR here.

[dprotaso]

/ok-to-test

Thanks for clarifying - can we adjust the names a bit to match the properties in the webhook.Options type

ie. WEBHOOK_SECRET_NAME and webhook.SecretNameFromEnv

ctx := webhook.WithOptions(signals.NewContext(), webhook.Options{
	ServiceName: webhook.NameFromEnv(),
	Port:        webhook.PortFromEnv(8443),
	SecretName:  webhook.SecretNameFromEnv("operator-webhook-certs"),
})

[hhk7734]

@dprotaso I added your suggestion to this PR.

[dprotaso]

/ok-to-test
/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dprotaso, hhk7734

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