Fix --link to a container which net mode is container mode

Signed-off-by: Lei Jitang <leijitang@huawei.com>

daemon/daemon.go

@@ -774,6 +774,13 @@ func (daemon *Daemon) RegisterLinks(container *Container, hostConfig *runconfig.
 				//An error from daemon.Get() means this name could not be found
 				return fmt.Errorf("Could not get container for %s", parts["name"])
 			}
+			for child.hostConfig.NetworkMode.IsContainer() {
+				parts := strings.SplitN(string(child.hostConfig.NetworkMode), ":", 2)
+				child, err = daemon.Get(parts[1])
+				if err != nil {
+					return fmt.Errorf("Could not get container for %s", parts[1])
+				}
+			}
 			if child.hostConfig.NetworkMode.IsHost() {
 				return runconfig.ErrConflictHostNetworkAndLinks
 			}

integration-cli/docker_cli_run_test.go

@@ -379,6 +379,39 @@ func TestRunLinksContainerWithContainerId(t *testing.T) {
 	logDone("run - use a container id to link target work")
 }
 
+func TestRunLinkToContainerNetMode(t *testing.T) {
+	defer deleteAllContainers()
+
+	cmd := exec.Command(dockerBinary, "run", "--name", "test", "-d", "busybox", "top")
+	out, _, err := runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatalf("failed to run container: %v, output: %q", err, out)
+	}
+	cmd = exec.Command(dockerBinary, "run", "--name", "parent", "-d", "--net=container:test", "busybox", "top")
+	out, _, err = runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatalf("failed to run container: %v, output: %q", err, out)
+	}
+	cmd = exec.Command(dockerBinary, "run", "-d", "--link=parent:parent", "busybox", "top")
+	out, _, err = runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatalf("failed to run container: %v, output: %q", err, out)
+	}
+
+	cmd = exec.Command(dockerBinary, "run", "--name", "child", "-d", "--net=container:parent", "busybox", "top")
+	out, _, err = runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatalf("failed to run container: %v, output: %q", err, out)
+	}
+	cmd = exec.Command(dockerBinary, "run", "-d", "--link=child:child", "busybox", "top")
+	out, _, err = runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatalf("failed to run container: %v, output: %q", err, out)
+	}
+
+	logDone("run - link to a container which net mode is container success")
+}
+
 // Regression test for #4741
 func TestRunWithVolumesAsFiles(t *testing.T) {
 	defer deleteAllContainers()