Better error for missing container runtime

cmd/root.go

@@ -29,7 +29,9 @@ var rootCmd = &cobra.Command{
 		}
 
 		if err := runStart(cmd.Context(), rt); err != nil {
-			fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+			if !output.IsSilent(err) {
+				fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+			}
 			os.Exit(1)
 		}
 	},

cmd/start.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/localstack/lstk/internal/output"
 	"github.com/localstack/lstk/internal/runtime"
 	"github.com/spf13/cobra"
 )
@@ -21,7 +22,9 @@ var startCmd = &cobra.Command{
 		}
 
 		if err := runStart(cmd.Context(), rt); err != nil {
-			fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+			if !output.IsSilent(err) {
+				fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+			}
 			os.Exit(1)
 		}
 	},

internal/container/start.go

@@ -18,6 +18,11 @@ import (
 )
 
 func Start(ctx context.Context, rt runtime.Runtime, sink output.Sink, platformClient api.PlatformAPI, interactive bool) error {
+	if err := rt.IsHealthy(ctx); err != nil {
+		rt.EmitUnhealthyError(sink, err)
+		return output.NewSilentError(fmt.Errorf("runtime not healthy: %w", err))
+	}
+
 	tokenStorage, err := auth.NewTokenStorage()
 	if err != nil {
 		return fmt.Errorf("failed to initialize token storage: %w", err)

internal/container/start_test.go

@@ -0,0 +1,29 @@
+package container
+
+import (
+	"context"
+	"errors"
+	"io"
+	"testing"
+
+	"github.com/localstack/lstk/internal/output"
+	"github.com/localstack/lstk/internal/runtime"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/mock/gomock"
+)
+
+func TestStart_ReturnsEarlyIfRuntimeUnhealthy(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	mockRT := runtime.NewMockRuntime(ctrl)
+	mockRT.EXPECT().IsHealthy(gomock.Any()).Return(errors.New("cannot connect to Docker daemon"))
+	mockRT.EXPECT().EmitUnhealthyError(gomock.Any(), gomock.Any())
+
+	sink := output.NewPlainSink(io.Discard)
+
+	err := Start(context.Background(), mockRT, sink, nil, false)
+
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "runtime not healthy")
+	assert.True(t, output.IsSilent(err), "error should be silent since it was already emitted")
+}

internal/output/errors.go

@@ -0,0 +1,28 @@
+package output
+
+import "errors"
+
+// SilentError wraps an error that has already been displayed to the user
+// through the sink mechanism. Callers should check for this type and skip
+// printing the error again.
+type SilentError struct {
+	Err error
+}
+
+func (e *SilentError) Error() string {
+	return e.Err.Error()
+}
+
+func (e *SilentError) Unwrap() error {
+	return e.Err
+}
+
+func NewSilentError(err error) *SilentError {
+	return &SilentError{Err: err}
+}
+
+// IsSilent returns true if the error (or any error in its chain) is a SilentError.
+func IsSilent(err error) bool {
+	var silent *SilentError
+	return errors.As(err, &silent)
+}

internal/output/events.go

@@ -118,8 +118,8 @@ func EmitNote(sink Sink, text string) {
 	Emit(sink, MessageEvent{Severity: SeverityNote, Text: text})
 }
 
-func EmitWarning(sink Sink, message string) {
-	Emit(sink, MessageEvent{Severity: SeverityWarning, Text: message})
+func EmitWarning(sink Sink, text string) {
+	Emit(sink, MessageEvent{Severity: SeverityWarning, Text: text})
 }
 
 func EmitStatus(sink Sink, phase, container, detail string) {

internal/runtime/docker.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	stdruntime "runtime"
 	"strconv"
 	"strings"
 
@@ -15,6 +16,7 @@ import (
 	"github.com/docker/docker/client"
 	"github.com/docker/docker/pkg/stdcopy"
 	"github.com/docker/go-connections/nat"
+	"github.com/localstack/lstk/internal/output"
 )
 
 // DockerRuntime implements Runtime using the Docker API.
@@ -30,6 +32,33 @@ func NewDockerRuntime() (*DockerRuntime, error) {
 	return &DockerRuntime{client: cli}, nil
 }
 
+func (d *DockerRuntime) IsHealthy(ctx context.Context) error {
+	_, err := d.client.Ping(ctx)
+	if err != nil {
+		return fmt.Errorf("cannot connect to Docker daemon: %w", err)
+	}
+	return nil
+}
+
+func (d *DockerRuntime) EmitUnhealthyError(sink output.Sink, err error) {
+	actions := []output.ErrorAction{
+		{Label: "Install Docker:", Value: "https://docs.docker.com/get-docker/"},
+	}
+	switch stdruntime.GOOS {
+	case "darwin":
+		actions = append([]output.ErrorAction{{Label: "Start Docker Desktop:", Value: "open -a Docker"}}, actions...)
+	case "linux":
+		actions = append([]output.ErrorAction{{Label: "Start Docker:", Value: "sudo systemctl start docker"}}, actions...)
+	case "windows":
+		actions = append([]output.ErrorAction{{Label: "Start Docker Desktop:", Value: "Start-Process 'Docker Desktop'"}}, actions...)
+	}
+	output.EmitError(sink, output.ErrorEvent{
+		Title:   "Docker is not available",
+		Summary: err.Error(),
+		Actions: actions,
+	})
+}
+
 func (d *DockerRuntime) PullImage(ctx context.Context, imageName string, progress chan<- PullProgress) error {
 	reader, err := d.client.ImagePull(ctx, imageName, image.PullOptions{})
 	if err != nil {

internal/runtime/runtime.go

@@ -3,6 +3,8 @@ package runtime
 import (
 	"context"
 	"io"
+
+	"github.com/localstack/lstk/internal/output"
 )
 
 type ContainerConfig struct {
@@ -24,6 +26,8 @@ type PullProgress struct {
 
 // Runtime abstracts container runtime operations (Docker, Podman, Kubernetes, etc.)
 type Runtime interface {
+	IsHealthy(ctx context.Context) error
+	EmitUnhealthyError(sink output.Sink, err error)
 	PullImage(ctx context.Context, image string, progress chan<- PullProgress) error
 	Start(ctx context.Context, config ContainerConfig) (string, error)
 	Stop(ctx context.Context, containerName string) error