refactor: server CLI interface

- add start/stop subcommands
- handle startup check when no clients attached

internal/server/serverapp.go

@@ -45,6 +45,10 @@ type Params struct {
 // defaultChanSize is the default size of the dispatch channel.
 const defaultChanSize = 64
 
+// ErrOtherInstanceDetected is returned when another instance of the app is
+// detected on startup.
+var ErrOtherInstanceDetected = errors.New("another instance is currently running")
+
 // New creates a new application instance.
 func New(params Params) *App {
 	return &App{
@@ -180,6 +184,10 @@ func (a *App) Run(ctx context.Context) error {
 		return startupErr
 	} else if ok {
 		startMediaServerC <- struct{}{}
+	} else if internalAPI.GetClientCount() == 0 {
+		// startup check failed, and there are no clients connected to the API so
+		// probably in server-only mode. In this case, we just bail out.
+		return ErrOtherInstanceDetected
 	}
 
 	for {
@@ -447,3 +455,14 @@ func buildNetAddr(src config.RTMPSource) mediaserver.OptionalNetAddr {
 
 	return mediaserver.OptionalNetAddr{Enabled: true, NetAddr: domain.NetAddr(src.NetAddr)}
 }
+
+// Stop stops all containers and networks created by any instance of the app.
+func (a *App) Stop(ctx context.Context) error {
+	containerClient, err := container.NewClient(ctx, a.dockerClient, a.logger.With("component", "container_client"))
+	if err != nil {
+		return fmt.Errorf("create container client: %w", err)
+	}
+	defer containerClient.Close()
+
+	return closeOtherInstances(ctx, containerClient)
+}

main.go

@@ -48,7 +48,48 @@ func (e errInterrupt) ExitCode() int {
 }
 
 func main() {
-	serverSubcommands := []*cli.Command{
+	app := &cli.App{
+		Name:  "Octoplex",
+		Usage: "Octoplex is a live video restreamer for Docker.",
+		Commands: []*cli.Command{
+			{
+				Name:  "client",
+				Usage: "Run the client",
+				Action: func(c *cli.Context) error {
+					return runClient(c.Context, c)
+				},
+			},
+			{
+				Name:  "server",
+				Usage: "Manage the standalone server.",
+				Action: func(c *cli.Context) error {
+					return c.App.Command("server").Subcommands[0].Action(c)
+				},
+				Subcommands: []*cli.Command{
+					{
+						Name:        "start",
+						Usage:       "Start the server",
+						Description: "Start the standalone server, without a CLI client attached.",
+						Action: func(c *cli.Context) error {
+							return runServer(c.Context, c, serverConfig{
+								stderrAvailable: true,
+								handleSigInt:    true,
+								waitForClient:   false,
+							})
+						},
+					},
+					{
+						Name:        "stop",
+						Usage:       "Stop the server",
+						Description: "Stop all containers and networks created by Octoplex, and exit.",
+						Action: func(c *cli.Context) error {
+							return runServer(c.Context, c, serverConfig{
+								stderrAvailable: true,
+								handleSigInt:    false,
+								waitForClient:   false,
+							})
+						},
+					},
 					{
 						Name:  "print-config",
 						Usage: "Print the config file path",
@@ -63,38 +104,15 @@ func main() {
 							return editConfig()
 						},
 					},
-	}
-
-	app := &cli.App{
-		Name:  "Octoplex",
-		Usage: "Octoplex is a live video restreamer for Docker.",
-		Commands: []*cli.Command{
-			{
-				Name:  "client",
-				Usage: "Run the client",
-				Action: func(c *cli.Context) error {
-					return runClient(c.Context, c)
 				},
 			},
-			{
-				Name:  "server",
-				Usage: "Run the server",
-				Action: func(c *cli.Context) error {
-					return runServer(c.Context, c, serverConfig{
-						stderrAvailable: true,
-						handleSigInt:    true,
-						waitForClient:   false,
-					})
-				},
-				Subcommands: serverSubcommands,
-			},
 			{
 				Name:        "run",
 				Usage:       "Run server and client in the same process",
+				Description: "Run the server and client in the same process. This is useful for testing, debugging or running for a single user.",
 				Action: func(c *cli.Context) error {
 					return runClientAndServer(c)
 				},
-				Subcommands: serverSubcommands,
 			},
 			{
 				Name:  "version",
@@ -159,7 +177,7 @@ type serverConfig struct {
 	waitForClient   bool
 }
 
-func runServer(ctx context.Context, _ *cli.Context, serverCfg serverConfig) error {
+func runServer(ctx context.Context, c *cli.Context, serverCfg serverConfig) error {
 	ctx, cancel := context.WithCancelCause(ctx)
 	defer cancel(nil)
 
@@ -224,6 +242,10 @@ func runServer(ctx context.Context, _ *cli.Context, serverCfg serverConfig) erro
 		Logger:         logger,
 	})
 
+	if c.Command.Name == "stop" {
+		return app.Stop(ctx)
+	}
+
 	logger.Info(
 		"Starting server",
 		"version",
@@ -240,6 +262,11 @@ func runServer(ctx context.Context, _ *cli.Context, serverCfg serverConfig) erro
 		if errors.Is(err, context.Canceled) && errors.Is(context.Cause(ctx), errInterrupt{}) {
 			return context.Cause(ctx)
 		}
+		if errors.Is(err, server.ErrOtherInstanceDetected) {
+			msg := "Another instance of the server may be running.\n" +
+				"To stop the server, run `octoplex server stop`."
+			return cli.Exit(msg, 1)
+		}
 		return err
 	}