kn channel create does not honour `default-ch-webhook` settings

[kameshsampath]

Bug report

Using the docs https://knative.dev/docs/eventing/channels/default-channels/, we can configure the default channel, assume Kafka is installed and I configure the default-ch-webhook CM to be like:

apiVersion: v1
kind: ConfigMap
metadata:
  name: default-ch-webhook
  namespace: knative-eventing
data:
  default-ch-config: |
    clusterDefault:
      apiVersion: messaging.knative.dev/v1
      kind: InMemoryChannel
    namespaceDefaults:
      knativetutorial:
        apiVersion: messaging.knative.dev/v1beta1
        kind: KafkaChannel
        spec:
          numPartitions: 2
          replicationFactor: 1

NOTE: Kafka is configured and running correctly and so is KafkaChannel resource

When I do kn channel create my-events-ch -n knativetutorial, I expect the channel to be created as KafkaChannel type but its getting defaulted to InMemoryChannel

e.g.

$ kn channel -n knativetutorial ls

NAME           TYPE              URL                                                                AGE     READY   REASON
my-events-ch   InMemoryChannel   http://my-events-ch-kn-channel.knativetutorial.svc.cluster.local   4m33s   True

Expected behavior

cat <<EOF | kubectl create -f  -
apiVersion: messaging.knative.dev/v1
kind: Channel
metadata:
  name: my-events-ch
  namespace: knativetutorial
EOF

 kn channel ls
NAME           TYPE           URL                                                                AGE   READY   REASON
my-events-ch   KafkaChannel   http://my-events-ch-kn-channel.knativetutorial.svc.cluster.local   13s   True

Steps to reproduce the problem

1. Set default channel webhook settings to be like

apiVersion: v1
kind: ConfigMap
metadata:
  name: default-ch-webhook
  namespace: knative-eventing
data:
  default-ch-config: |
    clusterDefault:
      apiVersion: messaging.knative.dev/v1
      kind: InMemoryChannel
    namespaceDefaults:
      knativetutorial:
        apiVersion: messaging.knative.dev/v1beta1
        kind: KafkaChannel
        spec:
          numPartitions: 2
          replicationFactor: 1

2. Run the command kn channel create -n knativetutorial my-events-ch

kn version

Version:      v0.18.0
Build Date:   2020-10-07 19:07:26
Git Revision: 60f2c2c5
Supported APIs:
* Serving
  - serving.knative.dev/v1 (knative-serving v0.18.0)
* Eventing
  - sources.knative.dev/v1alpha2 (knative-eventing v0.18.0)
  - eventing.knative.dev/v1beta1 (knative-eventing v0.18.0)

Knative (serving/eventing) version

0.17.0

/kind good-first-issue

[rhuss]

We switched to use the default "Channel" CRD which actually uses the default as configured for the cluster. So actually I would expect it to be just "Channel" as type in the list. @navidshaikh do you know whether this was included in 0.18 ?

[kameshsampath]

@rhuss not sure I got what you meant, you mean default as the CM name ? can we not leverage the default-ch-webhook CM during the channel creation?

[aliok]

FYI, I bumped into this as well.

@rhuss, the configmap is not entirely ignored. Only the namespaceDefaults part.

So, kn simply uses the clusterDefault instead of using the namespaceDefaults when creating a resource for e.g. knativetutorial above.

[navidshaikh]

@navidshaikh do you know whether this was included in 0.18 ?

@rhuss : Yes, we populate messagingv1beta1.Channel and hand over to eventing.

@rhuss, the configmap is not entirely ignored. Only the namespaceDefaults part.
So, kn simply uses the clusterDefault instead of using the namespaceDefaults when creating a resource for e.g. knativetutorial above.

@aliok : kn doesnt know about the default channel config set via CM at all. It populates the messagingv1beta1.Channel spec and submits to eventing, the cluster/namespace defaults are then taken care by eventing layer.

I could reproduce the issue using (v1beta1 apis) yaml + kubectl as well. Cluster wide default works while namespace default doesn't.

- Setup eventing at v0.18.4 and kafka

- Set clusterwide channel to IMC (v1beta1) and namespace (knativetutorial) to Kafka (v1alpha1)

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: ConfigMap
metadata:
  name: default-ch-webhook
  namespace: knative-eventing
data:
  default-ch-config: |
    clusterDefault:
      apiVersion: messaging.knative.dev/v1beta1
      kind: InMemoryChannel
    namespaceDefault:
      knativetutorial:
        apiVersion: messaging.knative.dev/v1alpha1
        kind: KafkaChannel
        spec:
          numPartitions: 2
          replicationFactor: 1
EOF

create a channel in default namespace

cat <<EOF | kubectl apply -f -
apiVersion: messaging.knative.dev/v1beta1
kind: Channel
metadata:
  name: my-channel
  namespace: default
EOF

create a channel in knativetutorial namespace

cat <<EOF | kubectl apply -f -
apiVersion: messaging.knative.dev/v1beta1
kind: Channel
metadata:
  name: my-channel
  namespace: knativetutorial
EOF

verify using kn

kn channel list -A

NAMESPACE         NAME         TYPE              URL                                                              AGE     READY   REASON
default           my-channel   InMemoryChannel   http://my-channel-kn-channel.default.svc.cluster.local           9m38s   True    
knativetutorial   my-channel   InMemoryChannel   http://my-channel-kn-channel.knativetutorial.svc.cluster.local   8m48s   True    

notice that the channel in knativetutorial should be a kafka channel based on the CM set above

[aliok]

@navidshaikh thanks for trying this.

I did exactly the same as you did (creating stuff with YAML) but I did it with 0.17 of eventing, 0.17 of eventing-contrib, 0.18 of kn. I now also realized I used v1 API instead of v1beta for Channel.

I think it is most likely there's a bug in v1beta1 Channel reconciliation and since kn is creating the Channel with that version, we're having this problem.
UPDATE: see #1100 (comment)

I will verify though.

BTW, how is the process for kn to start using the new API versions?

[aliok]

oh, @navidshaikh I just realized the default-ch-webhook you posted above has a typo: namespaceDefault --> namespaceDefaults.

[aliok]

@navidshaikh sorry, the typo got me confused and I made assumptions in 2 comments earlier.

I don't understand why (since kn is not doing anything with the confirmap) but I think it happens on kn only.

Configure default-ch-webhook

$ cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: ConfigMap
metadata:
  name: default-ch-webhook
  namespace: knative-eventing
data:
  default-ch-config: |
    clusterDefault:
      apiVersion: messaging.knative.dev/v1beta1
      kind: InMemoryChannel
    namespaceDefaults:
      knativetutorial:
        apiVersion: messaging.knative.dev/v1alpha1
        kind: KafkaChannel
        spec:
          numPartitions: 2
          replicationFactor: 1
EOF

configmap/default-ch-webhook configured

Create a Channel in default ns and knativetutorial ns:

$ cat <<EOF | kubectl apply -f -
apiVersion: messaging.knative.dev/v1beta1
kind: Channel
metadata:
  name: my-channel
  namespace: default
EOF

$ cat <<EOF | kubectl apply -f -
apiVersion: messaging.knative.dev/v1beta1
kind: Channel
metadata:
  name: my-channel
  namespace: knativetutorial
EOF

List channels:

$ kn channels list -A
NAMESPACE         NAME         TYPE              URL                                                              AGE     READY   REASON
default           my-channel   InMemoryChannel   http://my-channel-kn-channel.default.svc.cluster.local           3m9s    True
knativetutorial   my-channel   KafkaChannel      http://my-channel-kn-channel.knativetutorial.svc.cluster.local   2m50s   True

Works as expected. I also tried using v1 of Channel and I saw the same result:

cat <<EOF | kubectl apply -f -
apiVersion: messaging.knative.dev/v1
kind: Channel
metadata:
  name: my-channel
  namespace: default
EOF

cat <<EOF | kubectl apply -f -
apiVersion: messaging.knative.dev/v1
kind: Channel
metadata:
  name: my-channel
  namespace: knativetutorial
EOF

But, when I create channels with kn, I see different results:

$ kn channel create my-events-ch -n default
Channel 'my-events-ch' created in namespace 'default'.
$ kn channel create my-events-ch -n knativetutorial
Channel 'my-events-ch' created in namespace 'knativetutorial'.
$ kn channels list -A
NAMESPACE         NAME           TYPE              URL                                                                AGE   READY   REASON
default           my-events-ch   InMemoryChannel   http://my-events-ch-kn-channel.default.svc.cluster.local           4s    True    
knativetutorial   my-events-ch   InMemoryChannel   http://my-events-ch-kn-channel.knativetutorial.svc.cluster.local   4s    True  

[aliok]

and, I tried this with Knative eventing 0.17.8, eventing-contrib 0.17.x, kn 0.18.latest

[aliok]

The root cause of this issue here is this one in Knative Eventing: knative/eventing#4514