portmap integration test: echo server runs in separate process

this way we're not mixing goroutines and namespaces

plugins/meta/portmap/portmap_suite_test.go

@@ -15,89 +15,64 @@
 package main
 
 import (
-	"fmt"
+	"math/rand"
 	"net"
-	"time"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
 
 	"github.com/containernetworking/plugins/pkg/ns"
 
 	. "github.com/onsi/ginkgo"
+	"github.com/onsi/ginkgo/config"
 	. "github.com/onsi/gomega"
+	"github.com/onsi/gomega/gbytes"
+	"github.com/onsi/gomega/gexec"
 
 	"testing"
 )
 
 func TestPortmap(t *testing.T) {
+	rand.Seed(config.GinkgoConfig.RandomSeed)
+
 	RegisterFailHandler(Fail)
 	RunSpecs(t, "portmap Suite")
 }
 
-// OpenEchoServer opens a server that listens until closeChan is closed.
-// It opens on a random port and sends the port number on portChan when
-// the server is up and running. If an error is encountered, closes portChan.
-// If closeChan is closed, closes the socket.
-func OpenEchoServer(portChan chan<- int, closeChan <-chan interface{}) error {
-	laddr, err := net.ResolveTCPAddr("tcp", "0.0.0.0:0")
-	if err != nil {
-		close(portChan)
-		return err
-	}
-	sock, err := net.ListenTCP("tcp", laddr)
-	if err != nil {
-		close(portChan)
-		return err
-	}
-	defer sock.Close()
+var echoServerBinaryPath string
 
-	switch addr := sock.Addr().(type) {
-	case *net.TCPAddr:
-		portChan <- addr.Port
-	default:
-		close(portChan)
-		return fmt.Errorf("addr cast failed!")
-	}
-	for {
-		select {
-		case <-closeChan:
-			break
-		default:
-		}
+var _ = SynchronizedBeforeSuite(func() []byte {
+	binaryPath, err := gexec.Build("github.com/containernetworking/plugins/plugins/meta/portmap/echosvr")
+	Expect(err).NotTo(HaveOccurred())
+	return []byte(binaryPath)
+}, func(data []byte) {
+	echoServerBinaryPath = string(data)
+})
 
-		sock.SetDeadline(time.Now().Add(time.Second))
-		con, err := sock.AcceptTCP()
-		if err != nil {
-			if opErr, ok := err.(*net.OpError); ok && opErr.Timeout() {
-				continue
-			}
-			continue
-		}
+var _ = SynchronizedAfterSuite(func() {}, func() {
+	gexec.CleanupBuildArtifacts()
+})
 
-		buf := make([]byte, 512)
-		con.Read(buf)
-		con.Write(buf)
-		con.Close()
-	}
+func startInNetNS(binPath string, netNS ns.NetNS) (*gexec.Session, error) {
+	baseName := filepath.Base(netNS.Path())
+	// we are relying on the netNS path living in /var/run/netns
+	// where `ip netns exec` can find it
+	cmd := exec.Command("ip", "netns", "exec", baseName, binPath)
+	session, err := gexec.Start(cmd, GinkgoWriter, GinkgoWriter)
+	return session, err
 }
 
-func RunEchoServerInNS(netNS ns.NetNS) (int, chan interface{}, error) {
-	portChan := make(chan int)
-	closeChan := make(chan interface{})
+func StartEchoServerInNamespace(netNS ns.NetNS) (int, *gexec.Session, error) {
+	session, err := startInNetNS(echoServerBinaryPath, netNS)
+	Expect(err).NotTo(HaveOccurred())
 
-	go func() {
-		err := netNS.Do(func(ns.NetNS) error {
-			OpenEchoServer(portChan, closeChan)
-			return nil
-		})
-		// Somehow the ns.Do failed
-		if err != nil {
-			close(portChan)
-		}
-	}()
+	// wait for it to print it's address on stdout
+	Eventually(session.Out).Should(gbytes.Say("\n"))
+	_, portString, err := net.SplitHostPort(strings.TrimSpace(string(session.Out.Contents())))
+	Expect(err).NotTo(HaveOccurred())
 
-	portNum := <-portChan
-	if portNum == 0 {
-		return 0, nil, fmt.Errorf("failed to execute server")
-	}
-
-	return portNum, closeChan, nil
+	port, err := strconv.Atoi(portString)
+	Expect(err).NotTo(HaveOccurred())
+	return port, session, nil
 }