/
status.go
193 lines (170 loc) · 4.77 KB
/
status.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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
// Copyright 2016 Google, 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 status
import (
"bytes"
"fmt"
"html"
"html/template"
"io"
"net/http"
"os"
"path/filepath"
"sync"
"time"
"golang.org/x/net/context"
log "github.com/golang/glog"
)
var (
binaryName = filepath.Base(os.Args[0])
hostname string
serverStart = time.Now()
statusMu sync.RWMutex
statusSections []section
statusTmpl = template.Must(reparse(nil))
statusFuncMap = make(template.FuncMap)
)
type section struct {
Banner string
Fragment string
F func() interface{}
}
// AddStatusFuncs merges the provided functions into the set of
// functions used to render /debug/status. Call this before AddStatusPart
// if your template requires custom functions.
func AddStatusFuncs(fmap template.FuncMap) {
statusMu.Lock()
defer statusMu.Unlock()
for name, fun := range fmap {
if _, ok := statusFuncMap[name]; ok {
panic("duplicate status func registered: " + name)
}
statusFuncMap[name] = fun
}
}
var statusHTML = `<!DOCTYPE html>
<html>
<head>
<title>Status for {{.BinaryName}}</title>
<style>
body {
font-family: sans-serif;
}
h1 {
clear: both;
width: 100%;
text-align: center;
font-size: 120%;
background: #eef;
}
.lefthand {
float: left;
width: 80%;
}
.righthand {
text-align: right;
}
</style>
</head>
<h1>Status for {{.BinaryName}}</h1>
<div>
<div class=lefthand>
Started: {{.StartTime}}<br>
</div>
<div class=righthand>
Running on {{.Hostname}}<br>
View <a href=/debug/vars>variables</a>,
<a href=/debug/pprof>debugging profiles</a>,
<a href=/debug/resources>resources</a>,
</div>
</div>`
func reparse(sections []section) (*template.Template, error) {
var buf bytes.Buffer
io.WriteString(&buf, `{{define "status"}}`)
io.WriteString(&buf, statusHTML)
for i, sec := range sections {
fmt.Fprintf(&buf, "<h1>%s</h1>\n", html.EscapeString(sec.Banner))
fmt.Fprintf(&buf, "{{$sec := index .Sections %d}}\n", i)
fmt.Fprintf(&buf, `{{template "sec-%d" call $sec.F}}`+"\n", i)
}
fmt.Fprintf(&buf, `</html>`)
io.WriteString(&buf, "{{end}}\n")
for i, sec := range sections {
fmt.Fprintf(&buf, `{{define "sec-%d"}}%s{{end}}\n`, i, sec.Fragment)
}
return template.New("").Funcs(statusFuncMap).Parse(buf.String())
}
// AddStatusPart adds a new section to status. frag is used as a
// subtemplate of the template used to render /debug/status, and will
// be executed using the value of invoking f at the time of the
// /debug/status request. frag is parsed and executed with the
// html/template package. Functions registered with AddStatusFuncs
// may be used in the template.
func AddStatusPart(banner, frag string, f func(context.Context) interface{}) {
statusMu.Lock()
defer statusMu.Unlock()
secs := append(statusSections, section{
Banner: banner,
Fragment: frag,
F: func() interface{} { return f(context.Background()) },
})
var err error
statusTmpl, err = reparse(secs)
if err != nil {
secs[len(secs)-1] = section{
Banner: banner,
Fragment: "<code>bad status template: {{.}}</code>",
F: func() interface{} { return err },
}
}
statusTmpl, _ = reparse(secs)
statusSections = secs
}
// AddStatusSection registers a function that generates extra
// information for /debug/status. If banner is not empty, it will be
// used as a header before the information. If more complex output
// than a simple string is required use AddStatusPart instead.
func AddStatusSection(banner string, f func(context.Context) string) {
AddStatusPart(banner, `{{.}}`, func(ctx context.Context) interface{} { return f(ctx) })
}
func statusHandler(w http.ResponseWriter, r *http.Request) {
statusMu.Lock()
defer statusMu.Unlock()
data := struct {
Sections []section
BinaryName string
Hostname string
StartTime string
}{
Sections: statusSections,
BinaryName: binaryName,
Hostname: hostname,
StartTime: serverStart.Format(time.RFC1123),
}
if err := statusTmpl.ExecuteTemplate(w, "status", data); err != nil {
log.Errorf("servenv: couldn't execute template: %v", err)
}
}
// StatusURLPath returns the path to the status page.
func StatusURLPath() string {
return "/debug/status"
}
func init() {
var err error
hostname, err = os.Hostname()
if err != nil {
log.Fatalf("os.Hostname: %v", err)
}
http.HandleFunc("/debug/status", statusHandler)
}