-
Notifications
You must be signed in to change notification settings - Fork 2.4k
/
handler.go
144 lines (125 loc) · 3.53 KB
/
handler.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
// Copyright (c) 2019 The Jaeger Authors.
// Copyright (c) 2017 Uber Technologies, Inc.
//
// 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 healthcheck
import (
"encoding/json"
"fmt"
"net/http"
"sync/atomic"
"time"
"go.uber.org/zap"
)
// Status represents the state of the service.
type Status int
const (
// Unavailable indicates the service is not able to handle requests
Unavailable Status = iota
// Ready indicates the service is ready to handle requests
Ready
// Broken indicates that the healthcheck itself is broken, not serving HTTP
Broken
)
func (s Status) String() string {
switch s {
case Unavailable:
return "unavailable"
case Ready:
return "ready"
case Broken:
return "broken"
default:
return "unknown"
}
}
type healthCheckResponse struct {
statusCode int
StatusMsg string `json:"status"`
UpSince time.Time `json:"upSince"`
Uptime string `json:"uptime"`
}
type state struct {
status Status
upSince time.Time
}
// HealthCheck provides an HTTP endpoint that returns the health status of the service
type HealthCheck struct {
state atomic.Value // stores state struct
logger *zap.Logger
responses map[Status]healthCheckResponse
}
// New creates a HealthCheck with the specified initial state.
func New() *HealthCheck {
hc := &HealthCheck{
logger: zap.NewNop(),
responses: map[Status]healthCheckResponse{
Unavailable: {
statusCode: http.StatusServiceUnavailable,
StatusMsg: "Server not available",
},
Ready: {
statusCode: http.StatusOK,
StatusMsg: "Server available",
},
},
}
hc.state.Store(state{status: Unavailable})
return hc
}
// SetLogger initializes a logger.
func (hc *HealthCheck) SetLogger(logger *zap.Logger) {
hc.logger = logger
}
// Handler creates a new HTTP handler.
func (hc *HealthCheck) Handler() http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
state := hc.getState()
template := hc.responses[state.status]
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(template.statusCode)
w.Write(hc.createRespBody(state, template))
})
}
func (hc *HealthCheck) createRespBody(state state, template healthCheckResponse) []byte {
resp := template // clone
if state.status == Ready {
resp.UpSince = state.upSince
resp.Uptime = fmt.Sprintf("%v", time.Since(state.upSince))
}
healthCheckStatus, _ := json.Marshal(resp)
return healthCheckStatus
}
// Set a new health check status
func (hc *HealthCheck) Set(status Status) {
oldState := hc.getState()
newState := state{status: status}
if status == Ready {
if oldState.status != Ready {
newState.upSince = time.Now()
}
}
hc.state.Store(newState)
hc.logger.Info("Health Check state change", zap.Stringer("status", status))
}
// Get the current status of this health check
func (hc *HealthCheck) Get() Status {
return hc.getState().status
}
func (hc *HealthCheck) getState() state {
return hc.state.Load().(state)
}
// Ready is a shortcut for Set(Ready) (kept for backwards compatibility)
func (hc *HealthCheck) Ready() {
hc.Set(Ready)
}