feat: improve Docker connection error handling

internal/app/app.go

@@ -14,6 +14,7 @@ import (
 	"git.netflux.io/rob/octoplex/internal/mediaserver"
 	"git.netflux.io/rob/octoplex/internal/replicator"
 	"git.netflux.io/rob/octoplex/internal/terminal"
+	"github.com/docker/docker/client"
 )
 
 // RunParams holds the parameters for running the application.
@@ -69,7 +70,15 @@ func Run(ctx context.Context, params RunParams) error {
 	containerClient, err := container.NewClient(ctx, params.DockerClient, logger.With("component", "container_client"))
 	if err != nil {
 		err = fmt.Errorf("create container client: %w", err)
-		ui.ShowFatalErrorModal(err)
+
+		var errString string
+		if client.IsErrConnectionFailed(err) {
+			errString = "Could not connect to Docker. Is Docker installed and running?"
+		} else {
+			errString = err.Error()
+		}
+		ui.ShowFatalErrorModal(errString)
+
 		emptyUI()
 		<-ui.C()
 		return err
@@ -86,7 +95,7 @@ func Run(ctx context.Context, params RunParams) error {
 	})
 	if err != nil {
 		err = fmt.Errorf("create mediaserver: %w", err)
-		ui.ShowFatalErrorModal(err)
+		ui.ShowFatalErrorModal(err.Error())
 		emptyUI()
 		<-ui.C()
 		return err

internal/app/integration_test.go

@@ -791,3 +791,42 @@ func TestIntegrationDockerClientError(t *testing.T) {
 
 	<-done
 }
+func TestIntegrationDockerConnectionError(t *testing.T) {
+	ctx, cancel := context.WithTimeout(t.Context(), 10*time.Minute)
+	defer cancel()
+
+	logger := testhelpers.NewTestLogger(t).With("component", "integration")
+	dockerClient, err := dockerclient.NewClientWithOpts(dockerclient.WithHost("http://docker.example.com"))
+	require.NoError(t, err)
+
+	configService := setupConfigService(t, config.Config{Sources: config.Sources{RTMP: config.RTMPSource{Enabled: true}}})
+	screen, screenCaptureC, getContents := setupSimulationScreen(t)
+
+	done := make(chan struct{})
+	go func() {
+		defer func() {
+			done <- struct{}{}
+		}()
+
+		err := app.Run(ctx, buildAppParams(t, configService, dockerClient, screen, screenCaptureC, logger))
+		require.ErrorContains(t, err, "dial tcp: lookup docker.example.com")
+		require.ErrorContains(t, err, "no such host")
+	}()
+
+	require.EventuallyWithT(
+		t,
+		func(t *assert.CollectT) {
+			assert.True(t, contentsIncludes(getContents(), "An error occurred:"), "expected to see error message")
+			assert.True(t, contentsIncludes(getContents(), "Could not connect to Docker. Is Docker installed"), "expected to see message")
+		},
+		5*time.Second,
+		time.Second,
+		"expected to see fatal error modal",
+	)
+	printScreen(t, getContents, "Ater displaying the fatal error modal")
+
+	// Quit the app, this should cause the done channel to receive.
+	sendKey(t, screen, tcell.KeyEnter, ' ')
+
+	<-done
+}

internal/terminal/terminal.go

@@ -386,13 +386,13 @@ func (ui *UI) ShowDestinationErrorModal(name string, err error) {
 
 // ShowFatalErrorModal displays the provided error. It sends a CommandQuit to the
 // command channel when the user selects the Quit button.
-func (ui *UI) ShowFatalErrorModal(err error) {
+func (ui *UI) ShowFatalErrorModal(errString string) {
 	ui.app.QueueUpdateDraw(func() {
 		ui.showModal(
 			pageNameModalFatalError,
 			fmt.Sprintf(
 				"An error occurred:\n\n%s",
-				err,
+				errString,
 			),
 			[]string{"Quit"},
 			false,