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
21package zap
22
23import (
24	"encoding/json"
25	"fmt"
26	"net/http"
27
28	"go.uber.org/zap/zapcore"
29)
30
31// ServeHTTP is a simple JSON endpoint that can report on or change the current
32// logging level.
33//
34// GET requests return a JSON description of the current logging level. PUT
35// requests change the logging level and expect a payload like:
36//   {"level":"info"}
37//
38// It's perfectly safe to change the logging level while a program is running.
39func (lvl AtomicLevel) ServeHTTP(w http.ResponseWriter, r *http.Request) {
40	type errorResponse struct {
41		Error string `json:"error"`
42	}
43	type payload struct {
44		Level *zapcore.Level `json:"level"`
45	}
46
47	enc := json.NewEncoder(w)
48
49	switch r.Method {
50
51	case http.MethodGet:
52		current := lvl.Level()
53		enc.Encode(payload{Level: &current})
54
55	case http.MethodPut:
56		var req payload
57
58		if errmess := func() string {
59			if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
60				return fmt.Sprintf("Request body must be well-formed JSON: %v", err)
61			}
62			if req.Level == nil {
63				return "Must specify a logging level."
64			}
65			return ""
66		}(); errmess != "" {
67			w.WriteHeader(http.StatusBadRequest)
68			enc.Encode(errorResponse{Error: errmess})
69			return
70		}
71
72		lvl.SetLevel(*req.Level)
73		enc.Encode(req)
74
75	default:
76		w.WriteHeader(http.StatusMethodNotAllowed)
77		enc.Encode(errorResponse{
78			Error: "Only GET and PUT are supported.",
79		})
80	}
81}
82