add http handler to export configuration state

pkg/kubelet/server/server.go

@@ -52,6 +52,7 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/server/stats"
 	"k8s.io/kubernetes/pkg/runtime"
 	"k8s.io/kubernetes/pkg/types"
+	"k8s.io/kubernetes/pkg/util/configz"
 	"k8s.io/kubernetes/pkg/util/flushwriter"
 	"k8s.io/kubernetes/pkg/util/httpstream"
 	"k8s.io/kubernetes/pkg/util/httpstream/spdy"
@@ -328,6 +329,8 @@ func (s *Server) InstallDebuggingHandlers() {
 		Operation("getContainerLogs"))
 	s.restfulCont.Add(ws)
 
+	configz.InstallHandler(s.restfulCont)
+
 	handlePprofEndpoint := func(req *restful.Request, resp *restful.Response) {
 		name := strings.TrimPrefix(req.Request.URL.Path, pprofBasePath)
 		switch name {

pkg/util/configz/configz.go

@@ -0,0 +1,86 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+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 configz
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+)
+
+var (
+	configsGuard sync.RWMutex
+	configs      = map[string]*Config{}
+)
+
+type Config struct {
+	val interface{}
+}
+
+func InstallHandler(m mux) {
+	m.Handle("/configz", http.HandlerFunc(handle))
+}
+
+type mux interface {
+	Handle(string, http.Handler)
+}
+
+func New(name string) (*Config, error) {
+	configsGuard.Lock()
+	defer configsGuard.Unlock()
+	if _, found := configs[name]; found {
+		return nil, fmt.Errorf("register config %q twice", name)
+	}
+	newConfig := Config{}
+	configs[name] = &newConfig
+	return &newConfig, nil
+}
+
+func Delete(name string) {
+	configsGuard.Lock()
+	defer configsGuard.Unlock()
+	delete(configs, name)
+}
+
+func (v *Config) Set(val interface{}) {
+	configsGuard.Lock()
+	defer configsGuard.Unlock()
+	v.val = val
+}
+
+func (v *Config) MarshalJSON() ([]byte, error) {
+	return json.Marshal(v.val)
+}
+
+func handle(w http.ResponseWriter, r *http.Request) {
+	if err := write(w); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+	}
+}
+
+func write(w io.Writer) error {
+	configsGuard.Lock()
+	defer configsGuard.Unlock()
+	b, err := json.Marshal(configs)
+	if err != nil {
+		return fmt.Errorf("error marshaling json: %v", err)
+	}
+	_, err = w.Write(b)
+	return err
+}

pkg/util/configz/configz_test.go

@@ -0,0 +1,78 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+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 configz
+
+import (
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestConfigz(t *testing.T) {
+	v, err := New("testing")
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	v.Set("blah")
+
+	s := httptest.NewServer(http.HandlerFunc(handle))
+	// TODO: Uncomment when fix #19254
+	// defer s.Close()
+
+	resp, err := http.Get(s.URL + "/configz")
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if string(body) != `{"testing":"blah"}` {
+		t.Fatalf("unexpected output: %v", err)
+	}
+
+	v.Set("bing")
+	resp, err = http.Get(s.URL + "/configz")
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	body, err = ioutil.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if string(body) != `{"testing":"bing"}` {
+		t.Fatalf("unexpected output: %v", err)
+	}
+
+	Delete("testing")
+	resp, err = http.Get(s.URL + "/configz")
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	body, err = ioutil.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if string(body) != `{}` {
+		t.Fatalf("unexpected output: %v", err)
+	}
+}