Merge pull request #32 from apcera/allow-external-listener

Allow nats to choose a random port when given port -1

server/const.go

@@ -13,6 +13,11 @@ const (
 	// DEFAULT_PORT is the deault port for client connections.
 	DEFAULT_PORT = 4222
 
+	// RANDOM_PORT is the value for port that, when supplied, will cause the
+	// server to listen on a randomly-chosen available port. The resolved port
+	// is available via the Addr() method.
+	RANDOM_PORT = -1
+
 	// DEFAULT_HOST defaults to all interfaces.
 	DEFAULT_HOST = "0.0.0.0"
 

server/opts.go

@@ -213,6 +213,9 @@ func processOptions(opts *Options) {
 	}
 	if opts.Port == 0 {
 		opts.Port = DEFAULT_PORT
+	} else if opts.Port == RANDOM_PORT {
+		// Choose randomly inside of net.Listen
+		opts.Port = 0
 	}
 	if opts.MaxConn == 0 {
 		opts.MaxConn = DEFAULT_MAX_CONNECTIONS

server/opts_test.go

@@ -31,6 +31,16 @@ func TestDefaultOptions(t *testing.T) {
 	}
 }
 
+func TestOptions_RandomPort(t *testing.T) {
+	opts := &Options{Port: RANDOM_PORT}
+	processOptions(opts)
+
+	if opts.Port != 0 {
+		t.Fatalf("Process of options should have resolved random port to "+
+			"zero.\nexpected: %d\ngot: %d\n", 0, opts.Port)
+	}
+}
+
 func TestConfigFile(t *testing.T) {
 	golden := &Options{
 		Host:        "apcera.me",

server/server.go

@@ -274,6 +274,19 @@ func (s *Server) AcceptLoop() {
 	s.listener = l
 	s.mu.Unlock()
 
+	// Write resolved port back to options.
+	_, port, err := net.SplitHostPort(l.Addr().String())
+	if err != nil {
+		Fatalf("Error parsing server address (%s): %s", l.Addr().String(), e)
+		return
+	}
+	portNum, err := strconv.Atoi(port)
+	if err != nil {
+		Fatalf("Error parsing server address (%s): %s", l.Addr().String(), e)
+		return
+	}
+	s.opts.Port = portNum
+
 	tmpDelay := ACCEPT_MIN_SLEEP
 
 	for s.isRunning() {

test/port_test.go

@@ -0,0 +1,41 @@
+// Copyright 2014 Apcera Inc. All rights reserved.
+
+package test
+
+import (
+	"net"
+	"strconv"
+	"testing"
+
+	"github.com/apcera/gnatsd/server"
+)
+
+func TestResolveRandomPort(t *testing.T) {
+	opts := &server.Options{Port: server.RANDOM_PORT}
+	s := RunServer(opts)
+	defer s.Shutdown()
+
+	addr := s.Addr()
+	_, port, err := net.SplitHostPort(addr.String())
+	if err != nil {
+		t.Fatalf("Expected no error: Got %v\n", err)
+	}
+
+	portNum, err := strconv.Atoi(port)
+	if err != nil {
+		t.Fatalf("Expected no error: Got %v\n", err)
+	}
+
+	if portNum == server.DEFAULT_PORT {
+		t.Fatalf("Expected server to choose a random port\nGot: %d", server.DEFAULT_PORT)
+	}
+
+	if portNum == server.RANDOM_PORT {
+		t.Fatalf("Expected server to choose a random port\nGot: %d", server.RANDOM_PORT)
+	}
+
+	if opts.Port != portNum {
+		t.Fatalf("Options port (%d) should have been overridden by chosen random port (%d)",
+			opts.Port, portNum)
+	}
+}

test/test.go

@@ -56,10 +56,16 @@ func RunServer(opts *server.Options) *server.Server {
 	go s.Start()
 
 	// Make sure we are running and can bind before returning.
-	addr := fmt.Sprintf("%s:%d", opts.Host, opts.Port)
 	end := time.Now().Add(10 * time.Second)
 	for time.Now().Before(end) {
-		conn, err := net.Dial("tcp", addr)
+		addr := s.Addr()
+		if addr == nil {
+			time.Sleep(10 * time.Millisecond)
+			// Retry. We might take a little while to open a connection.
+			continue
+		}
+
+		conn, err := net.Dial("tcp", addr.String())
 		if err != nil {
 			time.Sleep(50 * time.Millisecond)
 			// Retry