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