added service to fetch knative channel crds

[abhi-kn]

Fixes:
https://issues.redhat.com/browse/ODC-4171

Analysis / Root cause:
Presently knative/operator doesn't have discovery API to list available channels in cluster. And this API should be accessible to non-admin users as well.

Solution Description:
Dependant API doesn't seem to be available in 4.6 timeline so a backend service in console is added as workaround. API /api/console/knative-channels has been added to list channel CRDs for any non-admin users based on labelSelector duck.knative.dev/addressable & messaging.knative.dev/subscribable.
P.S: Have reused resource lister infrastructure created for listing knative event source crds.

Screen shots / Gifs for design review: n/a

Unit test coverage report: n/a

Test setup:

1. Install Serverless & Knative Apache Kafka operators
2. Create Knative Serving & Knative Eventing

Browser conformance:

• Chrome
• Firefox
• Safari
• Edge

[abhi-kn]

/assign @invincibleJai

[abhi-kn]

/assign @benjaminapetersen @christianvogt

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/assign @benjaminapetersen @christianvogt

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[invincibleJai]

It works as expected, have verified with cluster bot for both kubadmin and self-provisioner with view only access.

Response

{"kind":"CustomResourceDefinitionList","apiVersion":"apiextensions.k8s.io/v1","metadata":{"selfLink":"/apis/apiextensions.k8s.io/v1/customresourcedefinitions","resourceVersion":"35800"},"items":[{"metadata":{"name":"channels.messaging.knative.dev","labels":{"duck.knative.dev/addressable":"true","eventing.knative.dev/release":"v0.13.3","knative.dev/crd-install":"true","messaging.knative.dev/subscribable":"true"}},"spec":{"group":"messaging.knative.dev","names":{"plural":"channels","singular":"channel","shortNames":["ch"],"kind":"Channel","listKind":"ChannelList","categories":["all","knative","messaging","channel"]},"versions":[{"name":"v1alpha1","served":true,"storage":true},{"name":"v1beta1","served":true,"storage":false}]}},{"metadata":{"name":"inmemorychannels.messaging.knative.dev","labels":{"duck.knative.dev/addressable":"true","eventing.knative.dev/release":"v0.13.3","knative.dev/crd-install":"true","messaging.knative.dev/subscribable":"true"}},"spec":{"group":"messaging.knative.dev","names":{"plural":"inmemorychannels","singular":"inmemorychannel","shortNames":["imc"],"kind":"InMemoryChannel","listKind":"InMemoryChannelList","categories":["all","knative","messaging","channel"]},"versions":[{"name":"v1alpha1","served":true,"storage":true},{"name":"v1beta1","served":true,"storage":false}]}}]}

[abhi-kn]

/assign @bparees

[christianvogt]

@spadgett what was the reason why we aren't simply exposing an endpoint for fetching CRD metadata and let the client specify the label selectors? This would avoid the need for a new end point each time we to perform these searches.

[bparees]

/unassign
/assign @spadgett

[abhi-kn]

@spadgett what was the reason why we aren't simply exposing an endpoint for fetching CRD metadata and let the client specify the label selectors? This would avoid the need for a new end point each time we to perform these searches.

@christianvogt I think its not to good to do that way as the endpoint is accessible to all users

[spadgett]

@spadgett what was the reason why we aren't simply exposing an endpoint for fetching CRD metadata and let the client specify the label selectors? This would avoid the need for a new end point each time we to perform these searches.

Then basic users could list metadata for all CRDs by hitting the endpoint directly. If possible, I think we should work with upstream to solve this in the operator.

[spadgett]

/approve
/lgtm

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: abhi-kn, invincibleJai, spadgett

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