Move TCP UDP start up into server.Start()

CHANGELOG.asciidoc

@@ -67,6 +67,7 @@ https://github.com/elastic/beats/compare/v6.0.0-beta1...master[Check the HEAD di
 
 - Update init scripts to use the `test config` subcommand instead of the deprecated `-configtest` flag. {issue}4600[4600]
 - Get by default the credentials for connecting to Kibana from the Elasticsearch output configuration. {pull}4867[4867]
+- Move TCP UDP start up into `server.Start()` {pull}4903[4903]
 
 *Auditbeat*
 

metricbeat/helper/server/http/http.go

@@ -57,7 +57,7 @@ func NewHttpServer(mb mb.BaseMetricSet) (server.Server, error) {
 	return h, nil
 }
 
-func (h *HttpServer) Start() {
+func (h *HttpServer) Start() error {
 	go func() {
 
 		logp.Info("Starting http server on %s", h.server.Addr)
@@ -67,6 +67,7 @@ func (h *HttpServer) Start() {
 		}
 	}()
 
+	return nil
 }
 
 func (h *HttpServer) Stop() {

metricbeat/helper/server/server.go

@@ -11,7 +11,7 @@ const (
 // Server is an interface that can be used to implement servers which can accept data.
 type Server interface {
 	// Start is used to start the server at a well defined port.
-	Start()
+	Start() error
 	// Stop the server.
 	Stop()
 	// Get a channel of events.

metricbeat/helper/server/tcp/tcp.go

@@ -4,13 +4,16 @@ import (
 	"fmt"
 	"net"
 
+	"github.com/pkg/errors"
+
 	"github.com/elastic/beats/libbeat/common"
 	"github.com/elastic/beats/libbeat/logp"
 	"github.com/elastic/beats/metricbeat/helper/server"
 	"github.com/elastic/beats/metricbeat/mb"
 )
 
 type TcpServer struct {
+	tcpAddr           *net.TCPAddr
 	listener          *net.TCPListener
 	receiveBufferSize int
 	done              chan struct{}
@@ -42,25 +45,27 @@ func NewTcpServer(base mb.BaseMetricSet) (server.Server, error) {
 		return nil, err
 	}
 
-	listener, err := net.ListenTCP("tcp", addr)
-	if err != nil {
-		return nil, err
-	}
-
-	logp.Info("Started listening for TCP on: %s:%d", config.Host, config.Port)
 	return &TcpServer{
-		listener:          listener,
+		tcpAddr:           addr,
 		receiveBufferSize: config.ReceiveBufferSize,
 		done:              make(chan struct{}),
 		eventQueue:        make(chan server.Event),
 	}, nil
 }
 
-func (g *TcpServer) Start() {
-	go g.WatchMetrics()
+func (g *TcpServer) Start() error {
+	listener, err := net.ListenTCP("tcp", g.tcpAddr)
+	if err != nil {
+		return errors.Wrap(err, "failed to start TCP server")
+	}
+	g.listener = listener
+	logp.Info("Started listening for TCP on: %s", g.tcpAddr.String())
+
+	go g.watchMetrics()
+	return nil
 }
 
-func (g *TcpServer) WatchMetrics() {
+func (g *TcpServer) watchMetrics() {
 	buffer := make([]byte, g.receiveBufferSize)
 	for {
 		select {

metricbeat/helper/server/tcp/tcp_test.go

@@ -20,14 +20,9 @@ func GetTestTcpServer(host string, port int) (server.Server, error) {
 		return nil, err
 	}
 
-	listener, err := net.ListenTCP("tcp", addr)
-	if err != nil {
-		return nil, err
-	}
-
 	logp.Info("Started listening for TCP on: %s:%d", host, port)
 	return &TcpServer{
-		listener:          listener,
+		tcpAddr:           addr,
 		receiveBufferSize: 1024,
 		done:              make(chan struct{}),
 		eventQueue:        make(chan server.Event),
@@ -43,7 +38,12 @@ func TestTcpServer(t *testing.T) {
 		t.FailNow()
 	}
 
-	svc.Start()
+	err = svc.Start()
+	if err != nil {
+		t.Error(err)
+		t.FailNow()
+	}
+
 	defer svc.Stop()
 	writeToServer(t, "test1", host, port)
 	msg := <-svc.GetEvents()

metricbeat/helper/server/udp/udp.go

@@ -4,13 +4,16 @@ import (
 	"fmt"
 	"net"
 
+	"github.com/pkg/errors"
+
 	"github.com/elastic/beats/libbeat/common"
 	"github.com/elastic/beats/libbeat/logp"
 	"github.com/elastic/beats/metricbeat/helper/server"
 	"github.com/elastic/beats/metricbeat/mb"
 )
 
 type UdpServer struct {
+	udpaddr           *net.UDPAddr
 	listener          *net.UDPConn
 	receiveBufferSize int
 	done              chan struct{}
@@ -43,25 +46,28 @@ func NewUdpServer(base mb.BaseMetricSet) (server.Server, error) {
 		return nil, err
 	}
 
-	listener, err := net.ListenUDP("udp", addr)
-	if err != nil {
-		return nil, err
-	}
-
-	logp.Info("Started listening for UDP on: %s:%d", config.Host, config.Port)
 	return &UdpServer{
-		listener:          listener,
+		udpaddr:           addr,
 		receiveBufferSize: config.ReceiveBufferSize,
 		done:              make(chan struct{}),
 		eventQueue:        make(chan server.Event),
 	}, nil
 }
 
-func (g *UdpServer) Start() {
-	go g.WatchMetrics()
+func (g *UdpServer) Start() error {
+	listener, err := net.ListenUDP("udp", g.udpaddr)
+	if err != nil {
+		return errors.Wrap(err, "failed to start UDP server")
+	}
+
+	logp.Info("Started listening for UDP on: %s", g.udpaddr.String())
+	g.listener = listener
+
+	go g.watchMetrics()
+	return nil
 }
 
-func (g *UdpServer) WatchMetrics() {
+func (g *UdpServer) watchMetrics() {
 	buffer := make([]byte, g.receiveBufferSize)
 	for {
 		select {

metricbeat/helper/server/udp/udp_test.go

@@ -20,14 +20,9 @@ func GetTestUdpServer(host string, port int) (server.Server, error) {
 		return nil, err
 	}
 
-	listener, err := net.ListenUDP("udp", addr)
-	if err != nil {
-		return nil, err
-	}
-
 	logp.Info("Started listening for UDP on: %s:%d", host, port)
 	return &UdpServer{
-		listener:          listener,
+		udpaddr:           addr,
 		receiveBufferSize: 1024,
 		done:              make(chan struct{}),
 		eventQueue:        make(chan server.Event),
@@ -44,6 +39,11 @@ func TestUdpServer(t *testing.T) {
 	}
 
 	svc.Start()
+	if err != nil {
+		t.Error(err)
+		t.FailNow()
+	}
+
 	defer svc.Stop()
 	writeToServer(t, "test1", host, port)
 	msg := <-svc.GetEvents()

metricbeat/module/graphite/server/server.go

@@ -1,7 +1,10 @@
 package server
 
 import (
+	"github.com/pkg/errors"
+
 	"github.com/elastic/beats/libbeat/common/cfgwarn"
+	"github.com/elastic/beats/libbeat/logp"
 	serverhelper "github.com/elastic/beats/metricbeat/helper/server"
 	"github.com/elastic/beats/metricbeat/helper/server/tcp"
 	"github.com/elastic/beats/metricbeat/helper/server/udp"
@@ -61,7 +64,12 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 // Run method provides the Graphite server with a reporter with which events can be reported.
 func (m *MetricSet) Run(reporter mb.PushReporter) {
 	// Start event watcher
-	m.server.Start()
+	if err := m.server.Start(); err != nil {
+		err = errors.Wrap(err, "failed to start graphite server")
+		logp.Err("%v", err)
+		reporter.Error(err)
+		return
+	}
 
 	for {
 		select {