Use 9252 as default port for metrics server

commands/config.go

@@ -2,10 +2,13 @@ package commands
 
 import (
 	"fmt"
-	"gitlab.com/gitlab-org/gitlab-ci-multi-runner/common"
-	"gitlab.com/gitlab-org/gitlab-ci-multi-runner/network"
+	"net"
 	"os"
 	"path/filepath"
+	"strings"
+
+	"gitlab.com/gitlab-org/gitlab-ci-multi-runner/common"
+	"gitlab.com/gitlab-org/gitlab-ci-multi-runner/network"
 )
 
 func getDefaultConfigFile() string {
@@ -70,12 +73,22 @@ type configOptionsWithMetricsServer struct {
 	MetricsServerAddress string `long:"metrics-server" env:"METRICS_SERVER" description:"Metrics server listening address"`
 }
 
-func (c *configOptionsWithMetricsServer) metricsServerAddress() string {
+func (c *configOptionsWithMetricsServer) metricsServerAddress() (string, error) {
+	address := c.config.MetricsServerAddress
+
 	if c.MetricsServerAddress != "" {
-		return c.MetricsServerAddress
+		address = c.MetricsServerAddress
+	}
+
+	_, port, err := net.SplitHostPort(address)
+	if err != nil && !strings.Contains(err.Error(), "missing port in address") {
+		return address, err
 	}
 
-	return c.config.MetricsServerAddress
+	if len(port) == 0 {
+		return fmt.Sprintf("%s:%d", address, common.DefaultMetricsServerPort), nil
+	}
+	return c.config.MetricsServerAddress, nil
 }
 
 func init() {

commands/multi.go

@@ -370,14 +370,21 @@ func (mr *RunCommand) serveDebugData() {
 }
 
 func (mr *RunCommand) setupMetricsAndDebugServer() {
-	if mr.metricsServerAddress() == "" {
+	serverAddress, err := mr.metricsServerAddress()
+
+	if err != nil {
+		mr.log().Errorf("invalid metrics server address: %s", err.Error())
+		return
+	}
+
+	if serverAddress == "" {
 		log.Infoln("Metrics server disabled")
 		return
 	}
 
 	// We separate out the listener creation here so that we can return an error if
 	// the provided address is invalid or there is some other listener error.
-	listener, err := net.Listen("tcp", mr.metricsServerAddress())
+	listener, err := net.Listen("tcp", serverAddress)
 	if err != nil {
 		log.Fatalln(err)
 	}
@@ -389,7 +396,7 @@ func (mr *RunCommand) setupMetricsAndDebugServer() {
 	mr.serveMetrics()
 	mr.serveDebugData()
 
-	log.Infoln("Metrics server listening at", mr.metricsServerAddress())
+	log.Infoln("Metrics server listening at", serverAddress)
 }
 
 func (mr *RunCommand) Run() {

common/consts.go

@@ -22,5 +22,6 @@ const DefaultRestoreCacheAttempts = 1
 const KubernetesPollInterval = 3
 const KubernetesPollTimeout = 180
 const AfterScriptTimeout = 5 * time.Minute
+const DefaultMetricsServerPort = 9252
 
 var PreparationRetryInterval = 3 * time.Second