Implement lstk logs --follow

anisaoshafi · anisaoshafi · commit a90fc63654e1 · 2026-02-25T19:45:57.000+01:00
diff --git a/cmd/logs.go b/cmd/logs.go
@@ -11,18 +11,23 @@ import (
 
 var logsCmd = &cobra.Command{
 	Use:     "logs",
-	Short:   "Stream container logs",
-	Long:    "Stream logs from the LocalStack container in real-time. Press Ctrl+C to stop.",
+	Short:   "Show container logs",
+	Long:    "Show logs from the LocalStack container. Use --follow to stream in real-time.",
 	PreRunE: initConfig,
 	RunE: func(cmd *cobra.Command, args []string) error {
+		follow, err := cmd.Flags().GetBool("follow")
+		if err != nil {
+			return err
+		}
 		rt, err := runtime.NewDockerRuntime()
 		if err != nil {
 			return err
 		}
-		return container.Logs(cmd.Context(), rt, output.NewPlainSink(os.Stdout))
+		return container.Logs(cmd.Context(), rt, output.NewPlainSink(os.Stdout), follow)
 	},
 }
 
 func init() {
 	rootCmd.AddCommand(logsCmd)
+	logsCmd.Flags().BoolP("follow", "f", false, "Follow log output")
 }
diff --git a/internal/container/logs.go b/internal/container/logs.go
@@ -11,7 +11,7 @@ import (
 	"github.com/localstack/lstk/internal/runtime"
 )
 
-func Logs(ctx context.Context, rt runtime.Runtime, sink output.Sink) error {
+func Logs(ctx context.Context, rt runtime.Runtime, sink output.Sink, follow bool) error {
 	cfg, err := config.Get()
 	if err != nil {
 		return fmt.Errorf("failed to get config: %w", err)
@@ -26,7 +26,7 @@ func Logs(ctx context.Context, rt runtime.Runtime, sink output.Sink) error {
 	pr, pw := io.Pipe()
 	errCh := make(chan error, 1)
 	go func() {
-		err := rt.StreamLogs(ctx, c.Name(), pw)
+		err := rt.StreamLogs(ctx, c.Name(), pw, follow)
 		pw.CloseWithError(err)
 		errCh <- err
 	}()
diff --git a/internal/runtime/docker.go b/internal/runtime/docker.go
@@ -152,11 +152,11 @@ func (d *DockerRuntime) Logs(ctx context.Context, containerID string, tail int)
 	return string(logs), nil
 }
 
-func (d *DockerRuntime) StreamLogs(ctx context.Context, containerID string, out io.Writer) error {
+func (d *DockerRuntime) StreamLogs(ctx context.Context, containerID string, out io.Writer, follow bool) error {
 	reader, err := d.client.ContainerLogs(ctx, containerID, container.LogsOptions{
 		ShowStdout: true,
 		ShowStderr: true,
-		Follow:     true,
+		Follow:     follow,
 		Tail:       "all",
 	})
 	if err != nil {
diff --git a/internal/runtime/runtime.go b/internal/runtime/runtime.go
@@ -30,6 +30,6 @@ type Runtime interface {
 	Remove(ctx context.Context, containerName string) error
 	IsRunning(ctx context.Context, containerID string) (bool, error)
 	Logs(ctx context.Context, containerID string, tail int) (string, error)
-	StreamLogs(ctx context.Context, containerID string, out io.Writer) error
+	StreamLogs(ctx context.Context, containerID string, out io.Writer, follow bool) error
 	GetImageVersion(ctx context.Context, imageName string) (string, error)
 }
diff --git a/test/integration/logs_test.go b/test/integration/logs_test.go
@@ -13,22 +13,38 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestLogsCommandFailsWhenNotRunning(t *testing.T) {
+func TestLogsExitsByDefault(t *testing.T) {
 	requireDocker(t)
 	cleanup()
 	t.Cleanup(cleanup)
 
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 
+	startTestContainer(t, ctx)
+
 	cmd := exec.CommandContext(ctx, binaryPath(), "logs")
+	_, err := cmd.CombinedOutput()
+
+	require.NoError(t, err, "lstk logs should exit cleanly when container is running")
+}
+
+func TestLogsCommandFailsWhenNotRunning(t *testing.T) {
+	requireDocker(t)
+	cleanup()
+	t.Cleanup(cleanup)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, binaryPath(), "logs", "--follow")
 	out, err := cmd.CombinedOutput()
 
-	require.Error(t, err, "expected lstk logs to fail when container not running")
+	require.Error(t, err, "expected lstk logs --follow to fail when container not running")
 	assert.Contains(t, string(out), "emulator is not running")
 }
 
-func TestLogsCommandStreamsOutput(t *testing.T) {
+func TestLogsFollowStreamsOutput(t *testing.T) {
 	requireDocker(t)
 	cleanup()
 	t.Cleanup(cleanup)
@@ -40,12 +56,12 @@ func TestLogsCommandStreamsOutput(t *testing.T) {
 
 	const marker = "lstk-logs-test-marker"
 
-	logsCmd := exec.CommandContext(ctx, binaryPath(), "logs")
+	logsCmd := exec.CommandContext(ctx, binaryPath(), "logs", "--follow")
 	stdout, err := logsCmd.StdoutPipe()
 	require.NoError(t, err, "failed to get stdout pipe")
 
 	err = logsCmd.Start()
-	require.NoError(t, err, "failed to start lstk logs")
+	require.NoError(t, err, "failed to start lstk logs --follow")
 	t.Cleanup(func() { _ = logsCmd.Process.Kill() })
 
 	// Give lstk logs a moment to connect before generating output
@@ -74,6 +90,6 @@ func TestLogsCommandStreamsOutput(t *testing.T) {
 	select {
 	case <-found:
 	case <-ctx.Done():
-		t.Fatal("marker did not appear in lstk logs output within timeout")
+		t.Fatal("marker did not appear in lstk logs --follow output within timeout")
 	}
 }

Original file line number	Diff line number	Diff line change
`@@ -30,6 +30,6 @@ type Runtime interface {`
`30`	`30`	`Remove(ctx context.Context, containerName string) error`
`31`	`31`	`IsRunning(ctx context.Context, containerID string) (bool, error)`
`32`	`32`	`Logs(ctx context.Context, containerID string, tail int) (string, error)`
`33`		`- StreamLogs(ctx context.Context, containerID string, out io.Writer) error`
	`33`	`+ StreamLogs(ctx context.Context, containerID string, out io.Writer, follow bool) error`
`34`	`34`	`GetImageVersion(ctx context.Context, imageName string) (string, error)`
`35`	`35`	`}`