1 /* 2 Copyright 2015 The Kubernetes Authors. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 // Package configz serves ComponentConfig objects from running components. 18 // 19 // Each component that wants to serve its ComponentConfig creates a Config 20 // object, and the program should call InstallHandler once. e.g., 21 // 22 // func main() { 23 // boatConfig := getBoatConfig() 24 // planeConfig := getPlaneConfig() 25 // 26 // bcz, err := configz.New("boat") 27 // if err != nil { 28 // panic(err) 29 // } 30 // bcz.Set(boatConfig) 31 // 32 // pcz, err := configz.New("plane") 33 // if err != nil { 34 // panic(err) 35 // } 36 // pcz.Set(planeConfig) 37 // 38 // configz.InstallHandler(http.DefaultServeMux) 39 // http.ListenAndServe(":8080", http.DefaultServeMux) 40 // } 41 package configz 42 43 import ( 44 "encoding/json" 45 "fmt" 46 "net/http" 47 "sync" 48 ) 49 50 var ( 51 configsGuard sync.RWMutex 52 configs = map[string]*Config{} 53 ) 54 55 // Config is a handle to a ComponentConfig object. Don't create these directly; 56 // use New() instead. 57 type Config struct { 58 val interface{} 59 } 60 61 // InstallHandler adds an HTTP handler on the given mux for the "/configz" 62 // endpoint which serves all registered ComponentConfigs in JSON format. 63 func InstallHandler(m mux) { 64 m.Handle("/configz", http.HandlerFunc(handle)) 65 } 66 67 type mux interface { 68 Handle(string, http.Handler) 69 } 70 71 // New creates a Config object with the given name. Each Config is registered 72 // with this package's "/configz" handler. 73 func New(name string) (*Config, error) { 74 configsGuard.Lock() 75 defer configsGuard.Unlock() 76 if _, found := configs[name]; found { 77 return nil, fmt.Errorf("register config %q twice", name) 78 } 79 newConfig := Config{} 80 configs[name] = &newConfig 81 return &newConfig, nil 82 } 83 84 // Delete removes the named ComponentConfig from this package's "/configz" 85 // handler. 86 func Delete(name string) { 87 configsGuard.Lock() 88 defer configsGuard.Unlock() 89 delete(configs, name) 90 } 91 92 // Set sets the ComponentConfig for this Config. 93 func (v *Config) Set(val interface{}) { 94 configsGuard.Lock() 95 defer configsGuard.Unlock() 96 v.val = val 97 } 98 99 // MarshalJSON marshals the ComponentConfig as JSON data. 100 func (v *Config) MarshalJSON() ([]byte, error) { 101 return json.Marshal(v.val) 102 } 103 104 func handle(w http.ResponseWriter, r *http.Request) { 105 if err := write(w); err != nil { 106 http.Error(w, err.Error(), http.StatusInternalServerError) 107 } 108 } 109 110 func write(w http.ResponseWriter) error { 111 var b []byte 112 var err error 113 func() { 114 configsGuard.RLock() 115 defer configsGuard.RUnlock() 116 b, err = json.Marshal(configs) 117 }() 118 if err != nil { 119 return fmt.Errorf("error marshaling json: %v", err) 120 } 121 w.Header().Set("Content-Type", "application/json") 122 w.Header().Set("X-Content-Type-Options", "nosniff") 123 _, err = w.Write(b) 124 return err 125 } 126