feat(source): Add 'kn source list'

 Fixes #480
 - Add 'kn source list' listing the available sources COs
 - Use dynamic client to
       - find out available source types
       - find the COs in given namespace for each source type
 - Add --type flag to filter source list based on source type
 - Add unit tests
 - Add e2e tests
 - Add CHANGELOG entry

CHANGELOG.adoc

@@ -20,6 +20,10 @@
 |===
 | | Description | PR
 
+| 🎁
+| Add `kn source list`
+| https://github.com/knative/client/pull/666[#666]
+
 | 🧽
 | Support multiple revisions on `kn revision delete`
 | https://github.com/knative/client/pull/657[#657]

docs/cmd/kn_source.md

@@ -30,5 +30,6 @@ kn source [flags]
 * [kn source apiserver](kn_source_apiserver.md)	 - Kubernetes API Server Event Source command group
 * [kn source binding](kn_source_binding.md)	 - Sink binding command group
 * [kn source cronjob](kn_source_cronjob.md)	 - CronJob source command group
+* [kn source list](kn_source_list.md)	 - List available sources
 * [kn source list-types](kn_source_list-types.md)	 - List available source types
 

docs/cmd/kn_source_list.md

@@ -0,0 +1,51 @@
+## kn source list
+
+List available sources
+
+### Synopsis
+
+List available sources
+
+```
+kn source list [flags]
+```
+
+### Examples
+
+```
+
+  # List available eventing sources
+  kn source list
+
+  # List PingSource type sources
+  kn source list --type=PingSource
+
+  # List PingSource and ApiServerSource types sources
+  kn source list --type=PingSource --type=apiserversource
+```
+
+### 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].
+  -t, --type strings                  Filter list on given source type. This flag can be given multiple times.
+```
+
+### Options inherited from parent commands
+
+```
+      --config string       kn config file (default is $HOME/.kn/config.yaml)
+      --kubeconfig string   kubectl config file (default is $HOME/.kube/config)
+      --log-http            log http traffic
+```
+
+### SEE ALSO
+
+* [kn source](kn_source.md)	 - Event source command group
+

go.mod

@@ -5,7 +5,6 @@ require (
 	contrib.go.opencensus.io/exporter/prometheus v0.1.0 // indirect
 	contrib.go.opencensus.io/exporter/stackdriver v0.13.0 // indirect
 	github.com/google/go-containerregistry v0.0.0-20200212224832-c629a66d7231 // indirect
-	github.com/magiconair/properties v1.8.0
 	github.com/mattbaird/jsonpatch v0.0.0-20171005235357-81af80346b1a // indirect
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/openzipkin/zipkin-go v0.2.2 // indirect

pkg/dynamic/client.go

@@ -15,6 +15,10 @@
 package dynamic
 
 import (
+	"fmt"
+	"strings"
+
+	"github.com/spf13/cobra"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/labels"
@@ -31,6 +35,16 @@ const (
 	sourcesLabelValue = "true"
 )
 
+// SourceListFilters defines flags used for kn source list to filter sources on types
+type SourceListFilters struct {
+	filters []string
+}
+
+// Add attaches the SourceListFilters flags to given command
+func (s *SourceListFilters) Add(cmd *cobra.Command) {
+	cmd.Flags().StringSliceVarP(&s.filters, "type", "t", nil, "Filter list on given source type. This flag can be given multiple times.")
+}
+
 // KnDynamicClient to client-go Dynamic client. All methods are relative to the
 // namespace specified during construction
 type KnDynamicClient interface {
@@ -43,6 +57,9 @@ type KnDynamicClient interface {
 	// ListSourceCRDs returns list of eventing sources CRDs
 	ListSourcesTypes() (*unstructured.UnstructuredList, error)
 
+	// ListSources returns list of available sources COs
+	ListSources(f *SourceListFilters) (*unstructured.UnstructuredList, error)
+
 	// RawClient returns the raw dynamic client interface
 	RawClient() dynamic.Interface
 }
@@ -94,3 +111,86 @@ func (c *knDynamicClient) ListSourcesTypes() (*unstructured.UnstructuredList, er
 func (c knDynamicClient) RawClient() dynamic.Interface {
 	return c.client
 }
+
+// ListSources returns list of available sources COs
+func (c *knDynamicClient) ListSources(f *SourceListFilters) (*unstructured.UnstructuredList, error) {
+	var sourceList unstructured.UnstructuredList
+	options := metav1.ListOptions{}
+	sourceTypes, err := c.ListSourcesTypes()
+	if err != nil {
+		return nil, err
+	}
+
+	namespace := c.Namespace()
+	// For each source type available, find out CO
+	for _, source := range sourceTypes.Items {
+		//  only find COs if this source type is given in filter
+		if f != nil && f.filters != nil {
+			// find source kind before hand to fail early
+			sourceKind, err := kindFromUnstructured(&source)
+			if err != nil {
+				return nil, err
+			}
+
+			// if this source is not given in filter flags continue
+			if !sliceContainsIgnoreCase(sourceKind, f.filters) {
+				continue
+			}
+		}
+
+		gvr, err := gvrFromUnstructured(&source)
+		if err != nil {
+			return nil, err
+		}
+
+		sList, err := c.client.Resource(gvr).Namespace(namespace).List(options)
+		if err != nil {
+			return nil, err
+		}
+
+		if len(sList.Items) > 0 {
+			sourceList.Items = append(sourceList.Items, sList.Items...)
+		}
+		sourceList.SetGroupVersionKind(sList.GetObjectKind().GroupVersionKind())
+	}
+	return &sourceList, nil
+}
+
+func gvrFromUnstructured(u *unstructured.Unstructured) (gvr schema.GroupVersionResource, err error) {
+	content := u.UnstructuredContent()
+	group, found, err := unstructured.NestedString(content, "spec", "group")
+	if err != nil || !found {
+		return gvr, fmt.Errorf("can't find source GVR: %v", err)
+	}
+	version, found, err := unstructured.NestedString(content, "spec", "version")
+	if err != nil || !found {
+		return gvr, fmt.Errorf("can't find source GVR: %v", err)
+	}
+	resource, found, err := unstructured.NestedString(content, "spec", "names", "plural")
+	if err != nil || !found {
+		return gvr, fmt.Errorf("can't find source GVR: %v", err)
+	}
+	return schema.GroupVersionResource{
+		Group:    group,
+		Version:  version,
+		Resource: resource,
+	}, nil
+}
+
+func kindFromUnstructured(u *unstructured.Unstructured) (string, error) {
+	content := u.UnstructuredContent()
+	kind, found, err := unstructured.NestedString(content, "spec", "names", "kind")
+	if !found || err != nil {
+		return "", fmt.Errorf("can't find source kind: %v", err)
+	}
+	return kind, nil
+}
+
+func sliceContainsIgnoreCase(s string, slice []string) bool {
+	for _, each := range slice {
+		if strings.EqualFold(s, each) {
+			return true
+		}
+	}
+	return false
+}