Add plugins required flag (#40)

* add required plugins flag.

* update plugins logs.

* add plugins subcommand.

* move preflight to prerun.

cmd/plugins.go

@@ -0,0 +1,49 @@
+package cmd
+
+import (
+	"encoding/json"
+	"os"
+
+	"github.com/demodesk/neko/internal/config"
+	"github.com/demodesk/neko/internal/plugins"
+	"github.com/rs/zerolog/log"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	command := &cobra.Command{
+		Use:   "plugins [directory]",
+		Short: "load, verify and list plugins",
+		Long:  `load, verify and list plugins`,
+		Run:   pluginsCmd,
+		Args:  cobra.MaximumNArgs(1),
+	}
+	root.AddCommand(command)
+}
+
+func pluginsCmd(cmd *cobra.Command, args []string) {
+	pluginDir := "/etc/neko/plugins"
+	if len(args) > 0 {
+		pluginDir = args[0]
+	}
+	log.Info().Str("dir", pluginDir).Msg("plugins directory")
+
+	plugs := plugins.New(&config.Plugins{
+		Enabled:  true,
+		Required: true,
+		Dir:      pluginDir,
+	})
+
+	meta := plugs.Metadata()
+	if len(meta) == 0 {
+		log.Fatal().Msg("no plugins found")
+	}
+
+	// marshal indent to stdout
+	dec := json.NewEncoder(os.Stdout)
+	dec.SetIndent("", "  ")
+	err := dec.Encode(meta)
+	if err != nil {
+		log.Fatal().Err(err).Msg("unable to marshal metadata")
+	}
+}

cmd/serve.go

@@ -27,11 +27,10 @@ func init() {
 		Use:    "serve",
 		Short:  "serve neko streaming server",
 		Long:   `serve neko streaming server`,
-		Run:   service.Command,
+		PreRun: service.PreRun,
+		Run:    service.Run,
 	}
 
-	cobra.OnInitialize(service.Preflight)
-
 	if err := service.Init(command); err != nil {
 		log.Panic().Err(err).Msg("unable to initialize configuration")
 	}
@@ -91,7 +90,7 @@ func (c *serve) Init(cmd *cobra.Command) error {
 	return nil
 }
 
-func (c *serve) Preflight() {
+func (c *serve) PreRun(cmd *cobra.Command, args []string) {
 	c.logger = log.With().Str("service", "neko").Logger()
 
 	c.configs.Desktop.Set()
@@ -198,7 +197,7 @@ func (c *serve) Shutdown() {
 	c.logger.Err(err).Msg("member manager disconnect")
 }
 
-func (c *serve) Command(cmd *cobra.Command, args []string) {
+func (c *serve) Run(cmd *cobra.Command, args []string) {
 	c.logger.Info().Msg("starting neko server")
 	c.Start(cmd)
 	c.logger.Info().Msg("neko ready")

internal/config/plugins.go

@@ -8,6 +8,7 @@ import (
 type Plugins struct {
 	Enabled  bool
 	Dir      string
+	Required bool
 }
 
 func (Plugins) Init(cmd *cobra.Command) error {
@@ -21,10 +22,16 @@ func (Plugins) Init(cmd *cobra.Command) error {
 		return err
 	}
 
+	cmd.PersistentFlags().Bool("plugins.required", false, "if true, neko will exit if there is an error when loading a plugin")
+	if err := viper.BindPFlag("plugins.required", cmd.PersistentFlags().Lookup("plugins.required")); err != nil {
+		return err
+	}
+
 	return nil
 }
 
 func (s *Plugins) Set() {
 	s.Enabled = viper.GetBool("plugins.enabled")
 	s.Dir = viper.GetString("plugins.dir")
+	s.Required = viper.GetBool("plugins.required")
 }

internal/plugins/dependency.go

@@ -15,88 +15,113 @@ type dependency struct {
 	logger    zerolog.Logger
 }
 
+func (a *dependency) findPlugin(name string) (*dependency, bool) {
+	if a == nil {
+		return nil, false
+	}
+
+	if a.plugin.Name() == name {
+		return a, true
+	}
+
+	for _, dep := range a.dependsOn {
+		plug, ok := dep.findPlugin(name)
+		if ok {
+			return plug, true
+		}
+	}
+
+	return nil, false
+}
+
+func (a *dependency) startPlugin(pm types.PluginManagers) error {
+	if a.invoked {
+		return nil
+	}
+
+	a.invoked = true
+
+	for _, do := range a.dependsOn {
+		if err := do.startPlugin(pm); err != nil {
+			return fmt.Errorf("plugin's '%s' dependency: %w", a.plugin.Name(), err)
+		}
+	}
+
+	err := a.plugin.Start(pm)
+	if err != nil {
+		return fmt.Errorf("plugin '%s' failed to start: %w", a.plugin.Name(), err)
+	}
+
+	a.logger.Info().Str("plugin", a.plugin.Name()).Msg("plugin started")
+	return nil
+}
+
 type dependiencies struct {
 	deps   map[string]*dependency
 	logger zerolog.Logger
 }
 
 func (d *dependiencies) addPlugin(plugin types.Plugin) error {
-	plug, ok := d.deps[plugin.Name()]
+	pluginName := plugin.Name()
+
+	plug, ok := d.deps[pluginName]
 	if !ok {
 		plug = &dependency{}
 	} else if plug.plugin != nil {
-		return fmt.Errorf("plugin '%s' already added", plugin.Name())
+		return fmt.Errorf("plugin '%s' already added", pluginName)
 	}
 
 	plug.plugin = plugin
 	plug.logger = d.logger
-	d.deps[plugin.Name()] = plug
+	d.deps[pluginName] = plug
 
 	dplug, ok := plugin.(types.DependablePlugin)
 	if !ok {
 		return nil
 	}
 
-	for _, dep := range dplug.DependsOn() {
-		var dependsOn *dependency
-		dependsOn, ok = d.deps[dep]
+	for _, depName := range dplug.DependsOn() {
+		dependsOn, ok := d.deps[depName]
 		if !ok {
 			dependsOn = &dependency{}
 		} else if dependsOn.plugin != nil {
 			// if there is a cyclical dependency, break it and return error
-			if tdep := dependsOn.findPlugin(plugin.Name()); tdep != nil {
+			if tdep, ok := dependsOn.findPlugin(pluginName); ok {
 				dependsOn.dependsOn = nil
-				delete(d.deps, plugin.Name())
-				return fmt.Errorf("cyclical dependency detected: '%s' <-> '%s'", plugin.Name(), tdep.plugin.Name())
+				delete(d.deps, pluginName)
+				return fmt.Errorf("cyclical dependency detected: '%s' <-> '%s'", pluginName, tdep.plugin.Name())
 			}
 		}
 
 		plug.dependsOn = append(plug.dependsOn, dependsOn)
-		d.deps[dep] = dependsOn
+		d.deps[depName] = dependsOn
 	}
 
 	return nil
 }
 
+func (d *dependiencies) findPlugin(name string) (*dependency, bool) {
+	for _, dep := range d.deps {
+		plug, ok := dep.findPlugin(name)
+		if ok {
+			return plug, true
+		}
+	}
+	return nil, false
+}
+
 func (d *dependiencies) start(pm types.PluginManagers) error {
-	for _, p := range d.deps {
-		if err := p.start(pm); err != nil {
+	for _, dep := range d.deps {
+		if err := dep.startPlugin(pm); err != nil {
 			return err
 		}
 	}
 	return nil
 }
 
-func (d *dependiencies) findPlugin(name string) (*dependency, bool) {
-	for _, p := range d.deps {
-		if found := p.findPlugin(name); found != nil {
-			return found, true
-		}
-	}
-	return nil, false
-}
-
-func (a *dependency) findPlugin(name string) *dependency {
-	if a == nil {
-		return nil
-	}
-
-	if a.plugin.Name() == name {
-		return a
-	}
-
-	for _, p := range a.dependsOn {
-		if found := p.findPlugin(name); found != nil {
-			return found
-		}
-	}
-
-	return nil
-}
-
 func (d *dependiencies) forEach(f func(*dependency) error) error {
-	for _, dp := range d.deps {
-		if err := f(dp); err != nil {
+	for _, dep := range d.deps {
+		if err := f(dep); err != nil {
 			return err
 		}
 	}
@@ -106,25 +131,3 @@ func (d *dependiencies) forEach(f func(*dependency) error) error {
 func (d *dependiencies) len() int {
 	return len(d.deps)
 }
-
-func (a *dependency) start(pm types.PluginManagers) error {
-	if a.invoked {
-		return nil
-	}
-
-	a.invoked = true
-
-	for _, do := range a.dependsOn {
-		if err := do.start(pm); err != nil {
-			return err
-		}
-	}
-
-	err := a.plugin.Start(pm)
-	a.logger.Err(err).Str("plugin", a.plugin.Name()).Msg("plugin start")
-	if err != nil {
-		return fmt.Errorf("plugin %s failed to start: %s", a.plugin.Name(), err)
-	}
-
-	return nil
-}

internal/plugins/manager.go

@@ -16,12 +16,14 @@ import (
 
 type ManagerCtx struct {
 	logger  zerolog.Logger
+	config  *config.Plugins
 	plugins dependiencies
 }
 
 func New(config *config.Plugins) *ManagerCtx {
 	manager := &ManagerCtx{
 		logger: log.With().Str("module", "plugins").Logger(),
+		config: config,
 		plugins: dependiencies{
 			deps: make(map[string]*dependency),
 		},
@@ -31,7 +33,13 @@ func New(config *config.Plugins) *ManagerCtx {
 
 	if config.Enabled {
 		err := manager.loadDir(config.Dir)
-		manager.logger.Err(err).Msgf("loading finished, total %d plugins", manager.plugins.len())
+
+		// only log error if plugin is not required
+		if err != nil && config.Required {
+			manager.logger.Fatal().Err(err).Msg("error loading plugins")
+		}
+
+		manager.logger.Info().Msgf("loading finished, total %d plugins", manager.plugins.len())
 	}
 
 	return manager
@@ -48,6 +56,13 @@ func (manager *ManagerCtx) loadDir(dir string) error {
 		}
 
 		err = manager.load(path)
+
+		// return error if plugin is required
+		if err != nil && manager.config.Required {
+			return err
+		}
+
+		// otherwise only log error if plugin is not required
 		manager.logger.Err(err).Str("plugin", path).Msg("loading a plugin")
 		return nil
 	})
@@ -70,25 +85,24 @@ func (manager *ManagerCtx) load(path string) error {
 	}
 
 	if err = manager.plugins.addPlugin(p); err != nil {
-		return fmt.Errorf("failed to add plugin '%s': %w", p.Name(), err)
+		return fmt.Errorf("failed to add plugin: %w", err)
 	}
 
-	manager.logger.Info().Msgf("loaded plugin '%s', total %d plugins", p.Name(), manager.plugins.len())
 	return nil
 }
 
 func (manager *ManagerCtx) InitConfigs(cmd *cobra.Command) {
-	_ = manager.plugins.forEach(func(plug *dependency) error {
-		if err := plug.plugin.Config().Init(cmd); err != nil {
-			log.Err(err).Str("plugin", plug.plugin.Name()).Msg("unable to initialize configuration")
+	_ = manager.plugins.forEach(func(d *dependency) error {
+		if err := d.plugin.Config().Init(cmd); err != nil {
+			log.Err(err).Str("plugin", d.plugin.Name()).Msg("unable to initialize configuration")
 		}
 		return nil
 	})
 }
 
 func (manager *ManagerCtx) SetConfigs() {
-	_ = manager.plugins.forEach(func(plug *dependency) error {
-		plug.plugin.Config().Set()
+	_ = manager.plugins.forEach(func(d *dependency) error {
+		d.plugin.Config().Set()
 		return nil
 	})
 }
@@ -98,18 +112,26 @@ func (manager *ManagerCtx) Start(
 	webSocketManager types.WebSocketManager,
 	apiManager types.ApiManager,
 ) {
-	_ = manager.plugins.start(types.PluginManagers{
+	err := manager.plugins.start(types.PluginManagers{
 		SessionManager:        sessionManager,
 		WebSocketManager:      webSocketManager,
 		ApiManager:            apiManager,
 		LoadServiceFromPlugin: manager.LookupService,
 	})
+
+	if err != nil {
+		if manager.config.Required {
+			manager.logger.Fatal().Err(err).Msg("failed to start plugins, exiting...")
+		} else {
+			manager.logger.Err(err).Msg("failed to start plugins, skipping...")
+		}
+	}
 }
 
 func (manager *ManagerCtx) Shutdown() error {
-	_ = manager.plugins.forEach(func(plug *dependency) error {
-		err := plug.plugin.Shutdown()
-		manager.logger.Err(err).Str("plugin", plug.plugin.Name()).Msg("plugin shutdown")
+	_ = manager.plugins.forEach(func(d *dependency) error {
+		err := d.plugin.Shutdown()
+		manager.logger.Err(err).Str("plugin", d.plugin.Name()).Msg("plugin shutdown")
 		return nil
 	})
 	return nil
@@ -128,3 +150,28 @@ func (manager *ManagerCtx) LookupService(pluginName string) (any, error) {
 
 	return expPlug.ExposeService(), nil
 }
+
+func (manager *ManagerCtx) Metadata() []types.PluginMetadata {
+	var plugins []types.PluginMetadata
+
+	_ = manager.plugins.forEach(func(d *dependency) error {
+		dependsOn := make([]string, 0)
+		deps, isDependalbe := d.plugin.(types.DependablePlugin)
+		if isDependalbe {
+			dependsOn = deps.DependsOn()
+		}
+
+		_, isExposable := d.plugin.(types.ExposablePlugin)
+
+		plugins = append(plugins, types.PluginMetadata{
+			Name:         d.plugin.Name(),
+			IsDependable: isDependalbe,
+			IsExposable:  isExposable,
+			DependsOn:    dependsOn,
+		})
+
+		return nil
+	})
+
+	return plugins
+}

pkg/types/plugins.go

@@ -28,6 +28,13 @@ type PluginConfig interface {
 	Set()
 }
 
+type PluginMetadata struct {
+	Name         string
+	IsDependable bool
+	IsExposable  bool
+	DependsOn    []string `json:",omitempty"`
+}
+
 type PluginManagers struct {
 	SessionManager        SessionManager
 	WebSocketManager      WebSocketManager