change the listening port

Dockerfile

@@ -8,6 +8,6 @@ RUN echo "deb http://apt-trace.datad0g.com.s3.amazonaws.com/ stable main" > /etc
  && apt-get clean \
  && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
-EXPOSE 7777/tcp
+EXPOSE 7777/tcp 8126/tcp
 
 ENTRYPOINT ["/opt/datadog-agent/bin/trace-agent"]

agent/main.go

@@ -35,6 +35,13 @@ func handleSignal(exit chan struct{}) {
 	}
 }
 
+// die logs an error message and makes the program exit immediately.
+func die(format string, args ...interface{}) {
+	log.Errorf(format, args...)
+	log.Flush()
+	os.Exit(1)
+}
+
 // opts are the command-line options
 var opts struct {
 	ddConfigFile string
@@ -126,6 +133,7 @@ func main() {
 	legacyConf, err := config.NewIfExists(opts.configFile)
 	if err != nil {
 		log.Errorf("%s: %v", opts.configFile, err)
+		log.Warnf("ignoring %s", opts.configFile)
 	}
 	if legacyConf != nil {
 		log.Infof("using legacy configuration from %s", opts.configFile)
@@ -134,14 +142,15 @@ func main() {
 	conf, err := config.NewIfExists(opts.ddConfigFile)
 	if err != nil {
 		log.Errorf("%s: %v", opts.ddConfigFile, err)
+		log.Warnf("ignoring %s", opts.ddConfigFile)
 	}
 	if conf != nil {
 		log.Infof("using configuration from %s", opts.ddConfigFile)
 	}
 
 	agentConf, err = config.NewAgentConfig(conf, legacyConf)
 	if err != nil {
-		panic(err)
+		die("%v", err)
 	}
 
 	// Exit if tracing is not enabled
@@ -164,13 +173,13 @@ func main() {
 	// replace the default logger
 	err = config.NewLoggerLevelCustom(level, agentConf.LogFilePath)
 	if err != nil {
-		panic(fmt.Errorf("error with logger: %v", err))
+		die("cannot create logger: %v", err)
 	}
 
 	// Initialize dogstatsd client
 	err = statsd.Configure(agentConf)
 	if err != nil {
-		fmt.Printf("Error configuring dogstatsd: %v", err)
+		die("cannot configure dogstatsd: %v", err)
 	}
 
 	// Seed rand

agent/receiver.go

@@ -14,6 +14,10 @@ import (
 	log "github.com/cihub/seelog"
 )
 
+// The trace agent used to listen on port 7777, but now uses port 8126. Keep
+// listening on 7777 during the transition.
+const legacyReceiverPort = 7777
+
 // APIVersion is a dumb way to version our collector handlers
 type APIVersion int
 
@@ -87,29 +91,47 @@ func (r *HTTPReceiver) Run() {
 	http.HandleFunc("/v0.3/services", r.httpHandleWithVersion(v03, r.handleServices))
 
 	addr := fmt.Sprintf("%s:%d", r.conf.ReceiverHost, r.conf.ReceiverPort)
-	log.Infof("listening for traces at http://%s/", addr)
+	if err := r.Listen(addr, ""); err != nil {
+		die("%v", err)
+	}
+
+	legacyAddr := fmt.Sprintf("%s:%d", r.conf.ReceiverHost, legacyReceiverPort)
+	if err := r.Listen(legacyAddr, " (legacy)"); err != nil {
+		log.Error(err)
+	}
+
+	go r.logStats()
+}
 
-	tcpL, err := net.Listen("tcp", addr)
+// Listen creates a new HTTP server listening on the provided address.
+func (r *HTTPReceiver) Listen(addr, logExtra string) error {
+	listener, err := net.Listen("tcp", addr)
 	if err != nil {
-		log.Error("could not create TCP listener")
-		panic(err)
+		return fmt.Errorf("cannot listen on %s: %v", addr, err)
 	}
 
-	sl, err := NewStoppableListener(tcpL, r.exit, r.conf.ConnectionLimit)
-	// some clients might use keep-alive and keep open their connections too long
-	// avoid leaks
-	timeout := 5
+	stoppableListener, err := NewStoppableListener(listener, r.exit,
+		r.conf.ConnectionLimit)
+	if err != nil {
+		return fmt.Errorf("cannot create stoppable listener: %v", err)
+	}
+
+	timeout := 5 * time.Second
 	if r.conf.ReceiverTimeout > 0 {
-		timeout = r.conf.ReceiverTimeout
+		timeout = time.Duration(r.conf.ReceiverTimeout) * time.Second
 	}
+
 	server := http.Server{
 		ReadTimeout:  time.Second * time.Duration(timeout),
 		WriteTimeout: time.Second * time.Duration(timeout),
 	}
 
-	go r.logStats()
-	go sl.Refresh(r.conf.ConnectionLimit)
-	go server.Serve(sl)
+	log.Infof("listening for traces at http://%s%s", addr, logExtra)
+
+	go stoppableListener.Refresh(r.conf.ConnectionLimit)
+	go server.Serve(stoppableListener)
+
+	return nil
 }
 
 func (r *HTTPReceiver) httpHandle(fn http.HandlerFunc) http.HandlerFunc {

agent/trace-agent.ini

@@ -68,6 +68,6 @@ oldest_span_cutoff_seconds=30
 ###################################################
 [trace.receiver]
 # the port that the Receiver should listen
-receiver_port=7777
+receiver_port=8126
 # how many unique connections to allow during one 30 second lease period
 connection_limit=2000

config/README.md

@@ -57,7 +57,7 @@ max_traces_per_second=10
 
 [trace.receiver]
 # the port that the Receiver should listen on
-receiver_port=7777
+receiver_port=8126
 # how many unique client connections to allow during one 30 second lease period
 connection_limit=2000
 

config/agent.go

@@ -121,7 +121,7 @@ func NewDefaultAgentConfig() *AgentConfig {
 		MaxTPS:          10,
 
 		ReceiverHost:    "localhost",
-		ReceiverPort:    7777,
+		ReceiverPort:    8126,
 		ConnectionLimit: 2000,
 
 		StatsdHost: "localhost",

config/config_test.go

@@ -30,7 +30,7 @@ func TestDefaultConfig(t *testing.T) {
 
 	// assert that some sane defaults are set
 	assert.Equal(agentConfig.ReceiverHost, "localhost")
-	assert.Equal(agentConfig.ReceiverPort, 7777)
+	assert.Equal(agentConfig.ReceiverPort, 8126)
 
 	assert.Equal(agentConfig.StatsdHost, "localhost")
 	assert.Equal(agentConfig.StatsdPort, 8125)