@@ -6,6 +6,7 @@ import (

 	"os/exec"

 	"strings"

 	"testing"

+	"time"

 	"github.com/docker/docker/pkg/iptables"

 )

@@ -177,3 +178,39 @@ func TestLinksNotStartedParentNotFail(t *testing.T) {

 	}

 	logDone("link - container start not failing on updating stopped parent links")

 }

+

+func TestLinksHostsFilesInject(t *testing.T) {

+	defer deleteAllContainers()

+

+	out, _, err := runCommandWithOutput(exec.Command(dockerBinary, "run", "-itd", "--name", "one", "busybox", "top"))

+	if err != nil {

+		t.Fatal(err, out)

+	}

+

+	idOne := strings.TrimSpace(out)

+

+	out, _, err = runCommandWithOutput(exec.Command(dockerBinary, "run", "-itd", "--name", "two", "--link", "one:onetwo", "busybox", "top"))

+	if err != nil {

+		t.Fatal(err, out)

+	}

+

+	idTwo := strings.TrimSpace(out)

+

+	time.Sleep(1 * time.Second)

+

+	contentOne, err := readContainerFile(idOne, "hosts")

+	if err != nil {

+		t.Fatal(err, string(contentOne))

+	}

+

+	contentTwo, err := readContainerFile(idTwo, "hosts")

+	if err != nil {

+		t.Fatal(err, string(contentTwo))

+	}

+

+	if !strings.Contains(string(contentTwo), "onetwo") {

+		t.Fatal("Host is not present in updated hosts file", string(contentTwo))

+	}

+

+	logDone("link - ensure containers hosts files are updated with the link alias.")

+}

@@ -736,10 +736,11 @@ func containerStorageFile(containerId, basename string) string {

 	return filepath.Join("/var/lib/docker/containers", containerId, basename)

 }

+// docker commands that use this function must be run with the '-d' switch.

 func runCommandAndReadContainerFile(filename string, cmd *exec.Cmd) ([]byte, error) {

 	out, _, err := runCommandWithOutput(cmd)

 	if err != nil {

-		return nil, err

+		return nil, fmt.Errorf("%v: %q", err, out)

 	}

 	time.Sleep(1 * time.Second)