let apiserver support api discovery

pkg/api/unversioned.go

@@ -22,16 +22,64 @@ import (
 
 // This file contains API types that are unversioned.
 
-// APIVersions lists the api versions that are available, to allow
-// version negotiation. APIVersions isn't just an unnamed array of
-// strings in order to allow for future evolution, though unversioned
+// APIVersions lists the versions that are available, to allow clients to
+// discover the API at /api, which is the root path of the legacy v1 API.
 type APIVersions struct {
+	// versions are the api versions that are available.
 	Versions []string `json:"versions"`
 }
 
+// APIGroupList is a list of APIGroup, to allow clients to discover the API at
+// /apis.
+type APIGroupList struct {
+	// groups is a list of APIGroup.
+	Groups []APIGroup `json:"groups"`
+}
+
+// APIGroup contains the name, the supported versions, and the preferred version
+// of a group.
+type APIGroup struct {
+	// name is the name of the group.
+	Name string `json:"name"`
+	// versions are the versions supported in this group.
+	Versions []GroupVersion `json:"versions"`
+	// preferredVersion is the version preferred by the API server, which
+	// probably is the storage version.
+	PreferredVersion GroupVersion `json:"preferredVersion,omitempty"`
+}
+
+// GroupVersion contains the "group/version" and "version" string of a version.
+// It is made a struct to keep extensiblity.
+type GroupVersion struct {
+	// groupVersion specifies the API group and version in the form "group/version"
+	GroupVersion string `json:"groupVersion"`
+	// version specifies the version in the form of "version". This is to save
+	// the clients the trouble of splitting the GroupVersion.
+	Version string `json:"version"`
+}
+
+// APIResource specifies the name of a resource and whether it is namespaced.
+type APIResource struct {
+	// name is the name of the resource.
+	Name string `json:"name"`
+	// namespaced indicates if a resource is namespaced or not.
+	Namespaced bool `json:"namespaced"`
+}
+
+// APIResourceList is a list of APIResource, it is used to expose the name of the
+// resources supported in a specific group and version, and if the resource
+// is namespaced.
+type APIResourceList struct {
+	// groupVersion is the group and version this APIResourceList is for.
+	GroupVersion string `json:"groupVersion"`
+	// resources contains the name of the resources and if they are namespaced.
+	APIResources []APIResource `json:"resources"`
+}
+
 // RootPaths lists the paths available at root.
-// For example: "/healthz", "/api".
+// For example: "/healthz", "/apis".
 type RootPaths struct {
+	// paths are the paths available at root.
 	Paths []string `json:"paths"`
 }