kubectl OpenAPI support

pkg/kubectl/cmd/util/openapi/openapi_getter.go

@@ -0,0 +1,71 @@
+/*
+Copyright 2017 The Kubernetes 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 openapi
+
+import (
+	"sync"
+
+	"k8s.io/client-go/discovery"
+)
+
+// synchronizedOpenAPIGetter fetches the openapi schema once and then caches it in memory
+type synchronizedOpenAPIGetter struct {
+	// Cached results
+	sync.Once
+	openAPISchema *Resources
+	err           error
+
+	serverVersion string
+	cacheDir      string
+	openAPIClient discovery.OpenAPISchemaInterface
+}
+
+var _ Getter = &synchronizedOpenAPIGetter{}
+
+// Getter is an interface for fetching openapi specs and parsing them into an Resources struct
+type Getter interface {
+	// openAPIData returns the parsed openAPIData
+	Get() (*Resources, error)
+}
+
+// NewOpenAPIGetter returns an object to return OpenAPIDatas which either read from a
+// local file cache or read from a server, and then stored in memory for subsequent invocations
+func NewOpenAPIGetter(cacheDir, serverVersion string, openAPIClient discovery.OpenAPISchemaInterface) Getter {
+	return &synchronizedOpenAPIGetter{
+		serverVersion: serverVersion,
+		cacheDir:      cacheDir,
+		openAPIClient: openAPIClient,
+	}
+}
+
+// Resources implements Getter
+func (g *synchronizedOpenAPIGetter) Get() (*Resources, error) {
+	g.Do(func() {
+		client := newCachingOpenAPIClient(g.openAPIClient, g.serverVersion, g.cacheDir)
+		result, err := client.openAPIData()
+		if err != nil {
+			g.err = err
+			return
+		}
+
+		// Save the result
+		g.openAPISchema = result
+	})
+
+	// Return the save result
+	return g.openAPISchema, g.err
+}