| /* |
| Copyright 2018 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 routes |
| |
| import ( |
| "fmt" |
| "html/template" |
| "io/ioutil" |
| "net/http" |
| "path" |
| "sync" |
| |
| "k8s.io/klog" |
| |
| "k8s.io/apiserver/pkg/server/mux" |
| ) |
| |
| var ( |
| lock = &sync.RWMutex{} |
| registeredFlags = map[string]debugFlag{} |
| ) |
| |
| // DebugFlags adds handlers for flags under /debug/flags. |
| type DebugFlags struct { |
| } |
| |
| // Install registers the APIServer's flags handler. |
| func (f DebugFlags) Install(c *mux.PathRecorderMux, flag string, handler func(http.ResponseWriter, *http.Request)) { |
| c.UnlistedHandle("/debug/flags", http.HandlerFunc(f.Index)) |
| c.UnlistedHandlePrefix("/debug/flags/", http.HandlerFunc(f.Index)) |
| |
| url := path.Join("/debug/flags", flag) |
| c.UnlistedHandleFunc(url, handler) |
| |
| f.addFlag(flag) |
| } |
| |
| // Index responds with the `/debug/flags` request. |
| // For example, "/debug/flags/v" serves the "--v" flag. |
| // Index responds to a request for "/debug/flags/" with an HTML page |
| // listing the available flags. |
| func (f DebugFlags) Index(w http.ResponseWriter, r *http.Request) { |
| lock.RLock() |
| defer lock.RUnlock() |
| if err := indexTmpl.Execute(w, registeredFlags); err != nil { |
| klog.Error(err) |
| } |
| } |
| |
| var indexTmpl = template.Must(template.New("index").Parse(`<html> |
| <head> |
| <title>/debug/flags/</title> |
| </head> |
| <body> |
| /debug/flags/<br> |
| <br> |
| flags:<br> |
| <table> |
| {{range .}} |
| <tr>{{.Flag}}<br> |
| {{end}} |
| </table> |
| <br> |
| full flags configurable<br> |
| </body> |
| </html> |
| `)) |
| |
| type debugFlag struct { |
| Flag string |
| } |
| |
| func (f DebugFlags) addFlag(flag string) { |
| lock.Lock() |
| defer lock.Unlock() |
| registeredFlags[flag] = debugFlag{flag} |
| } |
| |
| // StringFlagSetterFunc is a func used for setting string type flag. |
| type StringFlagSetterFunc func(string) (string, error) |
| |
| // StringFlagPutHandler wraps an http Handler to set string type flag. |
| func StringFlagPutHandler(setter StringFlagSetterFunc) http.HandlerFunc { |
| return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) { |
| switch { |
| case req.Method == "PUT": |
| body, err := ioutil.ReadAll(req.Body) |
| if err != nil { |
| writePlainText(http.StatusBadRequest, "error reading request body: "+err.Error(), w) |
| return |
| } |
| defer req.Body.Close() |
| response, err := setter(string(body)) |
| if err != nil { |
| writePlainText(http.StatusBadRequest, err.Error(), w) |
| return |
| } |
| writePlainText(http.StatusOK, response, w) |
| return |
| default: |
| writePlainText(http.StatusNotAcceptable, "unsupported http method", w) |
| return |
| } |
| }) |
| } |
| |
| // writePlainText renders a simple string response. |
| func writePlainText(statusCode int, text string, w http.ResponseWriter) { |
| w.Header().Set("Content-Type", "text/plain") |
| w.WriteHeader(statusCode) |
| fmt.Fprintln(w, text) |
| } |
