prometheus/web/web.go

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// Copyright 2013 The Prometheus Authors
// 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 web
import (
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"flag"
"fmt"
"html/template"
"io/ioutil"
"net"
"net/http"
"os"
"strings"
"time"
pprof_runtime "runtime/pprof"
"github.com/golang/glog"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/prometheus/web/api"
"github.com/prometheus/prometheus/web/blob"
)
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// Commandline flags.
var (
listenAddress = flag.String("web.listen-address", ":9090", "Address to listen on for the web interface, API, and telemetry.")
metricsPath = flag.String("web.telemetry-path", "/metrics", "Path under which to expose metrics.")
useLocalAssets = flag.Bool("web.use-local-assets", false, "Read assets/templates from file instead of binary.")
userAssetsPath = flag.String("web.user-assets", "", "Path to static asset directory, available at /user.")
enableQuit = flag.Bool("web.enable-remote-shutdown", false, "Enable remote service shutdown.")
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)
// WebService handles the HTTP endpoints with the exception of /api.
type WebService struct {
StatusHandler *PrometheusStatusHandler
MetricsHandler *api.MetricsService
AlertsHandler *AlertsHandler
ConsolesHandler *ConsolesHandler
GraphsHandler *GraphsHandler
QuitChan chan struct{}
}
// ServeForever serves the HTTP endpoints and only returns upon errors.
func (ws WebService) ServeForever(pathPrefix string) error {
http.Handle("/favicon.ico", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
http.Error(w, "", 404)
}))
http.Handle(pathPrefix, prometheus.InstrumentHandler(
pathPrefix, ws.StatusHandler,
))
http.Handle(pathPrefix + "alerts", prometheus.InstrumentHandler(
pathPrefix + "alerts", ws.AlertsHandler,
))
http.Handle(pathPrefix + "consoles/", prometheus.InstrumentHandler(
pathPrefix + "consoles/", http.StripPrefix(pathPrefix + "consoles/", ws.ConsolesHandler),
))
http.Handle(pathPrefix + "graph", prometheus.InstrumentHandler(
pathPrefix + "graph", ws.GraphsHandler,
))
http.Handle(pathPrefix + "heap", prometheus.InstrumentHandler(
pathPrefix + "heap", http.HandlerFunc(dumpHeap),
))
ws.MetricsHandler.RegisterHandler(pathPrefix)
http.Handle(pathPrefix + strings.TrimLeft(*metricsPath, "/"), prometheus.Handler())
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if *useLocalAssets {
http.Handle(pathPrefix + "static/", prometheus.InstrumentHandler(
pathPrefix + "static/", http.StripPrefix(pathPrefix + "static/", http.FileServer(http.Dir("web/static"))),
))
} else {
http.Handle(pathPrefix + "static/", prometheus.InstrumentHandler(
pathPrefix + "static/", http.StripPrefix(pathPrefix + "static/", new(blob.Handler)),
))
}
if *userAssetsPath != "" {
http.Handle(pathPrefix + "user/", prometheus.InstrumentHandler(
pathPrefix + "user/", http.StripPrefix(pathPrefix + "user/", http.FileServer(http.Dir(*userAssetsPath))),
))
}
if *enableQuit {
http.Handle(pathPrefix + "-/quit", http.HandlerFunc(ws.quitHandler))
}
if pathPrefix != "/" {
http.Handle("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
http.Redirect(w, r, pathPrefix, http.StatusFound)
}))
}
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glog.Info("listening on ", *listenAddress)
return http.ListenAndServe(*listenAddress, nil)
}
func (ws WebService) quitHandler(w http.ResponseWriter, r *http.Request) {
if r.Method != "POST" {
w.Header().Add("Allow", "POST")
w.WriteHeader(http.StatusMethodNotAllowed)
return
}
fmt.Fprintf(w, "Requesting termination... Goodbye!")
close(ws.QuitChan)
}
func getTemplateFile(name string) (string, error) {
if *useLocalAssets {
file, err := ioutil.ReadFile(fmt.Sprintf("web/templates/%s.html", name))
if err != nil {
glog.Errorf("Could not read %s template: %s", name, err)
return "", err
}
return string(file), nil
}
file, err := blob.GetFile(blob.TemplateFiles, name+".html")
if err != nil {
glog.Errorf("Could not read %s template: %s", name, err)
return "", err
}
return string(file), nil
}
func getConsoles(pathPrefix string) string {
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if _, err := os.Stat(*consoleTemplatesPath + "/index.html"); !os.IsNotExist(err) {
return pathPrefix + "consoles/index.html"
}
if *userAssetsPath != "" {
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if _, err := os.Stat(*userAssetsPath + "/index.html"); !os.IsNotExist(err) {
return pathPrefix + "user/index.html"
}
}
return ""
}
func getTemplate(name string, pathPrefix string) (t *template.Template, err error) {
t = template.New("_base")
t.Funcs(template.FuncMap{
"since": time.Since,
"getConsoles": func() string { return getConsoles(pathPrefix) },
"pathPrefix": func() string { return pathPrefix },
})
file, err := getTemplateFile("_base")
if err != nil {
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glog.Error("Could not read base template: ", err)
return nil, err
}
t.Parse(file)
file, err = getTemplateFile(name)
if err != nil {
glog.Error("Could not read base template: ", err)
return nil, err
}
t.Parse(file)
return
}
func executeTemplate(w http.ResponseWriter, name string, data interface{}, pathPrefix string) {
tpl, err := getTemplate(name, pathPrefix)
if err != nil {
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glog.Error("Error preparing layout template: ", err)
return
}
err = tpl.Execute(w, data)
if err != nil {
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glog.Error("Error executing template: ", err)
}
}
func dumpHeap(w http.ResponseWriter, r *http.Request) {
target := fmt.Sprintf("/tmp/%d.heap", time.Now().Unix())
f, err := os.Create(target)
if err != nil {
glog.Error("Could not dump heap: ", err)
}
fmt.Fprintf(w, "Writing to %s...", target)
defer f.Close()
pprof_runtime.WriteHeapProfile(f)
fmt.Fprintf(w, "Done")
}
// MustBuildServerURL returns the server URL and panics in case an error occurs.
func MustBuildServerURL(pathPrefix string) string {
_, port, err := net.SplitHostPort(*listenAddress)
if err != nil {
panic(err)
}
hostname, err := os.Hostname()
if err != nil {
panic(err)
}
return fmt.Sprintf("http://%s:%s%s", hostname, port, pathPrefix)
}