// Copyright (c) 2015 Arista Networks, Inc.
// Use of this source code is governed by the Apache License 2.0
// that can be found in the COPYING file.
// Package monitor provides an embedded HTTP server to expose
// metrics for monitoring
package monitor
import (
"expvar"
"fmt"
"net"
"net/http"
_ "net/http/pprof" // Go documentation recommended usage
"github.com/aristanetworks/goarista/netns"
"github.com/aristanetworks/glog"
)
// Server represents a monitoring server
type Server interface {
Run(serveMux *http.ServeMux)
}
// server contains information for the monitoring server
type server struct {
vrfName string
// Server name e.g. host[:port]
serverName string
}
// NewServer creates a new server struct
func NewServer(address string) Server {
vrfName, addr, err := netns.ParseAddress(address)
if err != nil {
glog.Errorf("Failed to parse address: %s", err)
}
return &server{
vrfName: vrfName,
serverName: addr,
}
}
func debugHandler(w http.ResponseWriter, r *http.Request) {
indexTmpl := `
/debug
/debug
`
fmt.Fprintf(w, indexTmpl)
}
// PrintableHistogram represents a Histogram that can be printed as
// a chart.
type PrintableHistogram interface {
Print() string
}
// Pretty prints the latency histograms
func histogramHandler(w http.ResponseWriter, r *http.Request) {
expvar.Do(func(kv expvar.KeyValue) {
if hist, ok := kv.Value.(PrintableHistogram); ok {
w.Write([]byte(hist.Print()))
}
})
}
// Run sets up the HTTP server and any handlers
func (s *server) Run(serveMux *http.ServeMux) {
serveMux.HandleFunc("/debug", debugHandler)
serveMux.HandleFunc("/debug/histograms", histogramHandler)
var listener net.Listener
err := netns.Do(s.vrfName, func() error {
var err error
listener, err = net.Listen("tcp", s.serverName)
return err
})
if err != nil {
glog.Fatalf("Could not start monitor server in VRF %q: %s", s.vrfName, err)
}
err = http.Serve(listener, serveMux)
if err != nil {
glog.Fatal("http serve returned with error:", err)
}
}