feat(channel): Manage knative eventing channels

- Use the default configured channel type

docs/cmd/kn.md

@@ -20,6 +20,7 @@ kn is the command line interface for managing Knative Serving and Eventing resou
 ### SEE ALSO
 
 * [kn broker](kn_broker.md)	 - Manage message broker
+* [kn channel](kn_channel.md)	 - Manage event channels
 * [kn completion](kn_completion.md)	 - Output shell completion code
 * [kn options](kn_options.md)	 - Print the list of flags inherited by all commands
 * [kn plugin](kn_plugin.md)	 - Manage kn plugins

docs/cmd/kn_channel.md

@@ -0,0 +1,34 @@
+## kn channel
+
+Manage event channels
+
+### Synopsis
+
+Manage event channels
+
+```
+kn channel COMMAND
+```
+
+### Options
+
+```
+  -h, --help   help for channel
+```
+
+### Options inherited from parent commands
+
+```
+      --config string       kn configuration file (default: ~/.config/kn/config.yaml)
+      --kubeconfig string   kubectl configuration file (default: ~/.kube/config)
+      --log-http            log http traffic
+```
+
+### SEE ALSO
+
+* [kn](kn.md)	 - kn manages Knative Serving and Eventing resources
+* [kn channel create](kn_channel_create.md)	 - Create an event channel
+* [kn channel delete](kn_channel_delete.md)	 - Delete a channel
+* [kn channel describe](kn_channel_describe.md)	 - Show details of a channel
+* [kn channel list](kn_channel_list.md)	 - List channels
+

docs/cmd/kn_channel_create.md

@@ -0,0 +1,39 @@
+## kn channel create
+
+Create an event channel
+
+### Synopsis
+
+Create an event channel
+
+```
+kn channel create NAME
+```
+
+### Examples
+
+```
+
+  # Create a channel 'pipe' in namespace 'flow'
+  kn channel create pipe -n flow
+```
+
+### Options
+
+```
+  -h, --help               help for create
+  -n, --namespace string   Specify the namespace to operate in.
+```
+
+### Options inherited from parent commands
+
+```
+      --config string       kn configuration file (default: ~/.config/kn/config.yaml)
+      --kubeconfig string   kubectl configuration file (default: ~/.kube/config)
+      --log-http            log http traffic
+```
+
+### SEE ALSO
+
+* [kn channel](kn_channel.md)	 - Manage event channels
+

docs/cmd/kn_channel_delete.md

@@ -0,0 +1,39 @@
+## kn channel delete
+
+Delete a channel
+
+### Synopsis
+
+Delete a channel
+
+```
+kn channel delete NAME
+```
+
+### Examples
+
+```
+
+  # Delete a channel 'pipe'
+  kn channel delete pipe
+```
+
+### Options
+
+```
+  -h, --help               help for delete
+  -n, --namespace string   Specify the namespace to operate in.
+```
+
+### Options inherited from parent commands
+
+```
+      --config string       kn configuration file (default: ~/.config/kn/config.yaml)
+      --kubeconfig string   kubectl configuration file (default: ~/.kube/config)
+      --log-http            log http traffic
+```
+
+### SEE ALSO
+
+* [kn channel](kn_channel.md)	 - Manage event channels
+

docs/cmd/kn_channel_describe.md

@@ -0,0 +1,43 @@
+## kn channel describe
+
+Show details of a channel
+
+### Synopsis
+
+Show details of a channel
+
+```
+kn channel describe NAME
+```
+
+### Examples
+
+```
+
+  # Describe a channel 'pipe'
+  kn channel describe pipe
+```
+
+### Options
+
+```
+      --allow-missing-template-keys   If true, ignore any errors in templates when a field or map key is missing in the template. Only applies to golang and jsonpath output formats. (default true)
+  -h, --help                          help for describe
+  -n, --namespace string              Specify the namespace to operate in.
+  -o, --output string                 Output format. One of: json|yaml|name|go-template|go-template-file|template|templatefile|jsonpath|jsonpath-file.
+      --template string               Template string or path to template file to use when -o=go-template, -o=go-template-file. The template format is golang templates [http://golang.org/pkg/text/template/#pkg-overview].
+  -v, --verbose                       More output.
+```
+
+### Options inherited from parent commands
+
+```
+      --config string       kn configuration file (default: ~/.config/kn/config.yaml)
+      --kubeconfig string   kubectl configuration file (default: ~/.kube/config)
+      --log-http            log http traffic
+```
+
+### SEE ALSO
+
+* [kn channel](kn_channel.md)	 - Manage event channels
+

docs/cmd/kn_channel_list.md

@@ -0,0 +1,47 @@
+## kn channel list
+
+List channels
+
+### Synopsis
+
+List channels
+
+```
+kn channel list
+```
+
+### Examples
+
+```
+
+  # List all channels
+  kn channel list
+
+  # List channels in YAML format
+  kn channel ping list -o yaml
+```
+
+### Options
+
+```
+  -A, --all-namespaces                If present, list the requested object(s) across all namespaces. Namespace in current context is ignored even if specified with --namespace.
+      --allow-missing-template-keys   If true, ignore any errors in templates when a field or map key is missing in the template. Only applies to golang and jsonpath output formats. (default true)
+  -h, --help                          help for list
+  -n, --namespace string              Specify the namespace to operate in.
+      --no-headers                    When using the default output format, don't print headers (default: print headers).
+  -o, --output string                 Output format. One of: json|yaml|name|go-template|go-template-file|template|templatefile|jsonpath|jsonpath-file.
+      --template string               Template string or path to template file to use when -o=go-template, -o=go-template-file. The template format is golang templates [http://golang.org/pkg/text/template/#pkg-overview].
+```
+
+### Options inherited from parent commands
+
+```
+      --config string       kn configuration file (default: ~/.config/kn/config.yaml)
+      --kubeconfig string   kubectl configuration file (default: ~/.kube/config)
+      --log-http            log http traffic
+```
+
+### SEE ALSO
+
+* [kn channel](kn_channel.md)	 - Manage event channels
+

pkg/errors/factory.go

@@ -41,6 +41,10 @@ func isEmptyConfigError(err error) bool {
 //Retrieves a custom error struct based on the original error APIStatus struct
 //Returns the original error struct in case it can't identify the kind of APIStatus error
 func GetError(err error) error {
+	if err == nil {
+		return nil
+	}
+
 	switch {
 	case isEmptyConfigError(err):
 		return newNoKubeConfig(err.Error())

pkg/kn/commands/channel/channel.go

@@ -0,0 +1,67 @@
+// Copyright © 2020 The Knative Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package channel
+
+import (
+	"github.com/spf13/cobra"
+
+	"k8s.io/client-go/tools/clientcmd"
+	clientv1beta1 "knative.dev/eventing/pkg/client/clientset/versioned/typed/messaging/v1beta1"
+
+	"knative.dev/client/pkg/kn/commands"
+	messagingv1beta1 "knative.dev/client/pkg/messaging/v1beta1"
+)
+
+// NewChannelCommand to manage event channels
+func NewChannelCommand(p *commands.KnParams) *cobra.Command {
+	channelCmd := &cobra.Command{
+		Use:   "channel COMMAND",
+		Short: "Manage event channels",
+	}
+	channelCmd.AddCommand(NewChannelCreateCommand(p))
+	channelCmd.AddCommand(NewChannelListCommand(p))
+	channelCmd.AddCommand(NewChannelDeleteCommand(p))
+	channelCmd.AddCommand(NewChannelDescribeCommand(p))
+	return channelCmd
+}
+
+var channelClientFactory func(config clientcmd.ClientConfig, namespace string) (messagingv1beta1.KnChannelsClient, error)
+
+func newChannelClient(p *commands.KnParams, cmd *cobra.Command) (messagingv1beta1.KnChannelsClient, error) {
+	namespace, err := p.GetNamespace(cmd)
+	if err != nil {
+		return nil, err
+	}
+
+	if channelClientFactory != nil {
+		config, err := p.GetClientConfig()
+		if err != nil {
+			return nil, err
+		}
+		return channelClientFactory(config, namespace)
+	}
+
+	clientConfig, err := p.RestConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	client, err := clientv1beta1.NewForConfig(clientConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	return messagingv1beta1.NewKnMessagingClient(client, namespace).ChannelsClient(), nil
+}

pkg/kn/commands/channel/create.go

@@ -0,0 +1,63 @@
+// Copyright © 2020 The Knative Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package channel
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/spf13/cobra"
+
+	knerrors "knative.dev/client/pkg/errors"
+	"knative.dev/client/pkg/kn/commands"
+	knmessagingv1beta1 "knative.dev/client/pkg/messaging/v1beta1"
+)
+
+// NewChannelCreateCommand to create event channels
+func NewChannelCreateCommand(p *commands.KnParams) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "create NAME",
+		Short: "Create an event channel",
+		Example: `
+  # Create a channel 'pipe' in namespace 'flow'
+  kn channel create pipe -n flow`,
+		RunE: func(cmd *cobra.Command, args []string) (err error) {
+			if len(args) != 1 {
+				return errors.New("'kn channel create' requires the channel name given as single argument")
+			}
+			name := args[0]
+
+			namespace, err := p.GetNamespace(cmd)
+			if err != nil {
+				return err
+			}
+
+			client, err := newChannelClient(p, cmd)
+			if err != nil {
+				return err
+			}
+
+			err = client.CreateChannel(knmessagingv1beta1.NewChannelBuilder(name).Build())
+			if err != nil {
+				return knerrors.GetError(err)
+			}
+
+			fmt.Fprintf(cmd.OutOrStdout(), "Channel '%s' created in namespace '%s'.\n", name, namespace)
+			return nil
+		},
+	}
+	commands.AddNamespaceFlags(cmd.Flags(), false)
+	return cmd
+}