fix: allow resource.Exec to correctly wait for process completion

dockertest.go

@@ -117,15 +117,25 @@ func (r *Resource) Exec(cmd []string, opts ExecOptions) (exitCode int, err error
 		Container:    r.Container.ID,
 		Cmd:          cmd,
 		Env:          opts.Env,
-		AttachStderr: opts.StdErr != nil,
-		AttachStdout: opts.StdOut != nil,
+		AttachStderr: true,
+		AttachStdout: true,
 		AttachStdin:  opts.StdIn != nil,
 		Tty:          opts.TTY,
 	})
 	if err != nil {
 		return -1, errors.Wrap(err, "Create exec failed")
 	}
 
+	// Always attach stderr/stdout, even if not specified, to ensure that exec
+	// waits with opts.Detach as false (default)
+	// ref: https://github.com/fsouza/go-dockerclient/issues/838
+	if opts.StdErr == nil {
+		opts.StdErr = io.Discard
+	}
+	if opts.StdOut == nil {
+		opts.StdOut = io.Discard
+	}
+
 	err = r.pool.Client.StartExec(exec.ID, dc.StartExecOptions{
 		InputStream:  opts.StdIn,
 		OutputStream: opts.StdOut,

dockertest_test.go

@@ -20,8 +20,10 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-var docker = os.Getenv("DOCKER_URL")
-var pool *Pool
+var (
+	docker = os.Getenv("DOCKER_URL")
+	pool   *Pool
+)
 
 func TestMain(m *testing.M) {
 	var err error
@@ -65,7 +67,6 @@ func TestMongo(t *testing.T) {
 
 	err = pool.Retry(func() error {
 		response, err := http.Get(fmt.Sprintf("http://127.0.0.1:%s", port))
-
 		if err != nil {
 			return err
 		}
@@ -197,7 +198,7 @@ func TestBuildImage(t *testing.T) {
 	dockerfilePath := dir + "/Dockerfile"
 	ioutil.WriteFile(dockerfilePath,
 		[]byte("FROM postgres:9.5"),
-		0644,
+		0o644,
 	)
 
 	resource, err := pool.BuildAndRun("postgres-test", dockerfilePath, nil)
@@ -219,7 +220,7 @@ ARG foo
 RUN echo -n $foo > /build-time-value
 CMD sleep 10
 `)),
-		0644,
+		0o644,
 	)
 
 	resource, err := pool.BuildAndRunWithBuildOptions(
@@ -467,3 +468,19 @@ func TestClientRaceCondition(t *testing.T) {
 		})
 	}
 }
+
+func TestExecStatus(t *testing.T) {
+	resource, err := pool.RunWithOptions(&RunOptions{
+		Repository: "alpine",
+		Tag:        "3.16",
+		Cmd:        []string{"tail", "-f", "/dev/null"},
+	})
+	defer resource.Close()
+	require.Nil(t, err)
+	exitCode, err := resource.Exec([]string{"/bin/false"}, ExecOptions{})
+	require.Nil(t, err)
+	require.Equal(t, 1, exitCode)
+	exitCode, err = resource.Exec([]string{"/bin/sh", "-c", "/bin/sleep 2 && exit 42"}, ExecOptions{})
+	require.Nil(t, err)
+	require.Equal(t, 42, exitCode)
+}