1 // Copyright (c) 2016 Uber Technologies, Inc. 2 // 3 // Permission is hereby granted, free of charge, to any person obtaining a copy 4 // of this software and associated documentation files (the "Software"), to deal 5 // in the Software without restriction, including without limitation the rights 6 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 7 // copies of the Software, and to permit persons to whom the Software is 8 // furnished to do so, subject to the following conditions: 9 // 10 // The above copyright notice and this permission notice shall be included in 11 // all copies or substantial portions of the Software. 12 // 13 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 14 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 15 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 16 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 17 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 18 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 19 // THE SOFTWARE. 20 21 package zap 22 23 import ( 24 "encoding/json" 25 "errors" 26 "fmt" 27 "io" 28 "net/http" 29 30 "go.uber.org/zap/zapcore" 31 ) 32 33 // ServeHTTP is a simple JSON endpoint that can report on or change the current 34 // logging level. 35 // 36 // # GET 37 // 38 // The GET request returns a JSON description of the current logging level like: 39 // 40 // {"level":"info"} 41 // 42 // # PUT 43 // 44 // The PUT request changes the logging level. It is perfectly safe to change the 45 // logging level while a program is running. Two content types are supported: 46 // 47 // Content-Type: application/x-www-form-urlencoded 48 // 49 // With this content type, the level can be provided through the request body or 50 // a query parameter. The log level is URL encoded like: 51 // 52 // level=debug 53 // 54 // The request body takes precedence over the query parameter, if both are 55 // specified. 56 // 57 // This content type is the default for a curl PUT request. Following are two 58 // example curl requests that both set the logging level to debug. 59 // 60 // curl -X PUT localhost:8080/log/level?level=debug 61 // curl -X PUT localhost:8080/log/level -d level=debug 62 // 63 // For any other content type, the payload is expected to be JSON encoded and 64 // look like: 65 // 66 // {"level":"info"} 67 // 68 // An example curl request could look like this: 69 // 70 // curl -X PUT localhost:8080/log/level -H "Content-Type: application/json" -d '{"level":"debug"}' 71 func (lvl AtomicLevel) ServeHTTP(w http.ResponseWriter, r *http.Request) { 72 if err := lvl.serveHTTP(w, r); err != nil { 73 w.WriteHeader(http.StatusInternalServerError) 74 fmt.Fprintf(w, "internal error: %v", err) 75 } 76 } 77 78 func (lvl AtomicLevel) serveHTTP(w http.ResponseWriter, r *http.Request) error { 79 type errorResponse struct { 80 Error string `json:"error"` 81 } 82 type payload struct { 83 Level zapcore.Level `json:"level"` 84 } 85 86 enc := json.NewEncoder(w) 87 88 switch r.Method { 89 case http.MethodGet: 90 return enc.Encode(payload{Level: lvl.Level()}) 91 92 case http.MethodPut: 93 requestedLvl, err := decodePutRequest(r.Header.Get("Content-Type"), r) 94 if err != nil { 95 w.WriteHeader(http.StatusBadRequest) 96 return enc.Encode(errorResponse{Error: err.Error()}) 97 } 98 lvl.SetLevel(requestedLvl) 99 return enc.Encode(payload{Level: lvl.Level()}) 100 101 default: 102 w.WriteHeader(http.StatusMethodNotAllowed) 103 return enc.Encode(errorResponse{ 104 Error: "Only GET and PUT are supported.", 105 }) 106 } 107 } 108 109 // Decodes incoming PUT requests and returns the requested logging level. 110 func decodePutRequest(contentType string, r *http.Request) (zapcore.Level, error) { 111 if contentType == "application/x-www-form-urlencoded" { 112 return decodePutURL(r) 113 } 114 return decodePutJSON(r.Body) 115 } 116 117 func decodePutURL(r *http.Request) (zapcore.Level, error) { 118 lvl := r.FormValue("level") 119 if lvl == "" { 120 return 0, errors.New("must specify logging level") 121 } 122 var l zapcore.Level 123 if err := l.UnmarshalText([]byte(lvl)); err != nil { 124 return 0, err 125 } 126 return l, nil 127 } 128 129 func decodePutJSON(body io.Reader) (zapcore.Level, error) { 130 var pld struct { 131 Level *zapcore.Level `json:"level"` 132 } 133 if err := json.NewDecoder(body).Decode(&pld); err != nil { 134 return 0, fmt.Errorf("malformed request body: %v", err) 135 } 136 if pld.Level == nil { 137 return 0, errors.New("must specify logging level") 138 } 139 return *pld.Level, nil 140 } 141