feat(publisher): Check if app port is open before publishing it. Fixes 3115

Check if the port that container exposes is open before adding to Etcd.

Author: glogiotatidis

publisher/server/publisher.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"log"
+	"net"
 	"os"
 	"regexp"
 	"strconv"
@@ -91,8 +92,9 @@ func (s *Server) publishContainer(container *docker.APIContainers, ttl time.Dura
 		keyPath := fmt.Sprintf("/deis/services/%s/%s", appName, containerName)
 		for _, p := range container.Ports {
 			port := strconv.Itoa(int(p.PublicPort))
-			if s.IsPublishableApp(containerName) {
-				s.setEtcd(keyPath, host+":"+port, uint64(ttl.Seconds()))
+			hostAndPort := host + ":" + port
+			if s.IsPublishableApp(containerName) && s.IsPortOpen(hostAndPort) {
+				s.setEtcd(keyPath, hostAndPort, uint64(ttl.Seconds()))
 			}
 			// TODO: support multiple exposed ports
 			break
@@ -113,12 +115,23 @@ func (s *Server) IsPublishableApp(name string) bool {
 		log.Println(err)
 		return false
 	}
+
 	if version >= latestRunningVersion(s.EtcdClient, appName) {
 		return true
 	}
 	return false
 }
 
+func (s *Server) IsPortOpen(hostAndPort string) bool {
+	portOpen := false
+	conn, err := net.Dial("tcp", hostAndPort)
+	if err == nil {
+		portOpen = true
+		defer conn.Close()
+	}
+	return portOpen
+}
+
 // latestRunningVersion retrieves the highest version of the application published
 // to etcd. If no app has been published, returns 0.
 func latestRunningVersion(client *etcd.Client, appName string) int {

publisher/server/publisher_test.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"net"
 	"testing"
 )
 
@@ -28,3 +29,19 @@ func TestIsPublishableApp(t *testing.T) {
 		t.Errorf("%s should be publishable", futureVersion)
 	}
 }
+
+func TestIsPortOpen(t *testing.T) {
+	ln, err := net.Listen("tcp4", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("Listen failed: %v", err)
+	}
+	defer ln.Close()
+
+	s := &Server{nil, nil}
+	if !s.IsPortOpen(ln.Addr().String()) {
+		t.Errorf("Port should be open")
+	}
+	if s.IsPortOpen("127.0.0.1:-1") {
+		t.Errorf("Port should be closed")
+	}
+}