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monitoring.go
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/
monitoring.go
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// Copyright 2017 Istio 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 monitoring
import (
"fmt"
"net"
"net/http"
"net/http/pprof"
"time"
"github.com/prometheus/client_golang/prometheus"
ocprom "go.opencensus.io/exporter/prometheus"
"go.opencensus.io/stats/view"
"istio.io/istio/pkg/log"
"istio.io/istio/pkg/version"
)
// Monitor is the server that exposes Prometheus metrics about Citadel.
type Monitor struct {
monitoringServer *http.Server
port int
closed chan bool
}
const (
metricsPath = "/metrics"
versionPath = "/version"
)
// NewMonitor creates a monitor.
func NewMonitor(port int, enableProfiling bool) (*Monitor, error) {
m := &Monitor{
port: port,
closed: make(chan bool),
}
mux := http.NewServeMux()
exporter, err := ocprom.NewExporter(ocprom.Options{Registry: prometheus.DefaultRegisterer.(*prometheus.Registry)})
if err != nil {
return nil, fmt.Errorf("could not set up prometheus exporter: %v", err)
}
view.RegisterExporter(exporter)
mux.Handle(metricsPath, exporter)
mux.HandleFunc(versionPath, func(out http.ResponseWriter, req *http.Request) {
if _, err := out.Write([]byte(version.Info.String())); err != nil {
log.Errorf("Unable to write version string: %v", err)
}
})
if enableProfiling {
mux.HandleFunc("/debug/pprof/", pprof.Index)
mux.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
mux.HandleFunc("/debug/pprof/profile", pprof.Profile)
mux.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
mux.HandleFunc("/debug/pprof/trace", pprof.Trace)
}
m.monitoringServer = &http.Server{
Handler: mux,
}
return m, nil
}
// Start starts the monitor server.
func (m *Monitor) Start(errCh chan<- error) {
// get the network stuff setup
listener, lErr := net.Listen("tcp", fmt.Sprintf(":%d", m.port))
if lErr != nil {
errCh <- fmt.Errorf("unable to listen on socket: %v", lErr)
return
}
log.Info("Monitor server started.")
err := m.monitoringServer.Serve(listener)
errCh <- fmt.Errorf("monitor server error: %v", err)
close(m.closed)
}
// Close stops the Monitoring server for Citadel.
func (m *Monitor) Close() error {
var err error
// This works around a race condition between Serve() and Close() functions.
// If Close() is called before Serve(), Serve() never returns.
// m.closed channel is used by Serve() to indicate that is has processed the Close signal
// and exited the function. Until Serve() exists, Close() periodically issues monitoringServer.Close().
L:
for {
err = m.monitoringServer.Close()
select {
case <-m.closed:
break L
default:
time.Sleep(20 * time.Millisecond)
}
}
return err
}