feat(prometheus): add metrics to Subsonic API and Plugins (#4266)

* Add prometheus metrics to subsonic and plugins

* address feedback, do not log error if operation is not supported

* add missing timestamp and client to stats

* remove .view from subsonic route

* directly inject DataStore in Prometheus, to avoid having to pass it in every call

Signed-off-by: Deluan <deluan@navidrome.org>

---------

Signed-off-by: Deluan <deluan@navidrome.org>
Co-authored-by: Deluan <deluan@navidrome.org>

plugins/adapter_media_agent.go

@@ -10,22 +10,23 @@ import (
 )
 
 // NewWasmMediaAgent creates a new adapter for a MetadataAgent plugin
-func newWasmMediaAgent(wasmPath, pluginID string, runtime api.WazeroNewRuntime, mc wazero.ModuleConfig) WasmPlugin {
+func newWasmMediaAgent(wasmPath, pluginID string, m *Manager, runtime api.WazeroNewRuntime, mc wazero.ModuleConfig) WasmPlugin {
 	loader, err := api.NewMetadataAgentPlugin(context.Background(), api.WazeroRuntime(runtime), api.WazeroModuleConfig(mc))
 	if err != nil {
 		log.Error("Error creating media metadata service plugin", "plugin", pluginID, "path", wasmPath, err)
 		return nil
 	}
 	return &wasmMediaAgent{
-		wasmBasePlugin: &wasmBasePlugin[api.MetadataAgent, *api.MetadataAgentPlugin]{
-			wasmPath:   wasmPath,
-			id:         pluginID,
-			capability: CapabilityMetadataAgent,
-			loader:     loader,
-			loadFunc: func(ctx context.Context, l *api.MetadataAgentPlugin, path string) (api.MetadataAgent, error) {
+		wasmBasePlugin: newWasmBasePlugin[api.MetadataAgent, *api.MetadataAgentPlugin](
+			wasmPath,
+			pluginID,
+			CapabilityMetadataAgent,
+			m.metrics,
+			loader,
+			func(ctx context.Context, l *api.MetadataAgentPlugin, path string) (api.MetadataAgent, error) {
 				return l.Load(ctx, path)
 			},
-		},
+		),
 	}
 }
 

plugins/adapter_media_agent_test.go

@@ -23,7 +23,7 @@ var _ = Describe("Adapter Media Agent", func() {
 		DeferCleanup(configtest.SetupConfig())
 		conf.Server.Plugins.Folder = testDataDir
 
-		mgr = createManager(nil)
+		mgr = createManager(nil, nil)
 		mgr.ScanPlugins()
 	})
 

plugins/adapter_scheduler_callback.go

@@ -9,22 +9,23 @@ import (
 )
 
 // newWasmSchedulerCallback creates a new adapter for a SchedulerCallback plugin
-func newWasmSchedulerCallback(wasmPath, pluginID string, runtime api.WazeroNewRuntime, mc wazero.ModuleConfig) WasmPlugin {
+func newWasmSchedulerCallback(wasmPath, pluginID string, m *Manager, runtime api.WazeroNewRuntime, mc wazero.ModuleConfig) WasmPlugin {
 	loader, err := api.NewSchedulerCallbackPlugin(context.Background(), api.WazeroRuntime(runtime), api.WazeroModuleConfig(mc))
 	if err != nil {
 		log.Error("Error creating scheduler callback plugin", "plugin", pluginID, "path", wasmPath, err)
 		return nil
 	}
 	return &wasmSchedulerCallback{
-		wasmBasePlugin: &wasmBasePlugin[api.SchedulerCallback, *api.SchedulerCallbackPlugin]{
-			wasmPath:   wasmPath,
-			id:         pluginID,
-			capability: CapabilitySchedulerCallback,
-			loader:     loader,
-			loadFunc: func(ctx context.Context, l *api.SchedulerCallbackPlugin, path string) (api.SchedulerCallback, error) {
+		wasmBasePlugin: newWasmBasePlugin[api.SchedulerCallback, *api.SchedulerCallbackPlugin](
+			wasmPath,
+			pluginID,
+			CapabilitySchedulerCallback,
+			m.metrics,
+			loader,
+			func(ctx context.Context, l *api.SchedulerCallbackPlugin, path string) (api.SchedulerCallback, error) {
 				return l.Load(ctx, path)
 			},
-		},
+		),
 	}
 }
 

plugins/adapter_scrobbler.go

@@ -12,22 +12,23 @@ import (
 	"github.com/tetratelabs/wazero"
 )
 
-func newWasmScrobblerPlugin(wasmPath, pluginID string, runtime api.WazeroNewRuntime, mc wazero.ModuleConfig) WasmPlugin {
+func newWasmScrobblerPlugin(wasmPath, pluginID string, m *Manager, runtime api.WazeroNewRuntime, mc wazero.ModuleConfig) WasmPlugin {
 	loader, err := api.NewScrobblerPlugin(context.Background(), api.WazeroRuntime(runtime), api.WazeroModuleConfig(mc))
 	if err != nil {
 		log.Error("Error creating scrobbler service plugin", "plugin", pluginID, "path", wasmPath, err)
 		return nil
 	}
 	return &wasmScrobblerPlugin{
-		wasmBasePlugin: &wasmBasePlugin[api.Scrobbler, *api.ScrobblerPlugin]{
-			wasmPath:   wasmPath,
-			id:         pluginID,
-			capability: CapabilityScrobbler,
-			loader:     loader,
-			loadFunc: func(ctx context.Context, l *api.ScrobblerPlugin, path string) (api.Scrobbler, error) {
+		wasmBasePlugin: newWasmBasePlugin[api.Scrobbler, *api.ScrobblerPlugin](
+			wasmPath,
+			pluginID,
+			CapabilityScrobbler,
+			m.metrics,
+			loader,
+			func(ctx context.Context, l *api.ScrobblerPlugin, path string) (api.Scrobbler, error) {
 				return l.Load(ctx, path)
 			},
-		},
+		),
 	}
 }
 

plugins/adapter_websocket_callback.go

@@ -9,22 +9,23 @@ import (
 )
 
 // newWasmWebSocketCallback creates a new adapter for a WebSocketCallback plugin
-func newWasmWebSocketCallback(wasmPath, pluginID string, runtime api.WazeroNewRuntime, mc wazero.ModuleConfig) WasmPlugin {
+func newWasmWebSocketCallback(wasmPath, pluginID string, m *Manager, runtime api.WazeroNewRuntime, mc wazero.ModuleConfig) WasmPlugin {
 	loader, err := api.NewWebSocketCallbackPlugin(context.Background(), api.WazeroRuntime(runtime), api.WazeroModuleConfig(mc))
 	if err != nil {
 		log.Error("Error creating WebSocket callback plugin", "plugin", pluginID, "path", wasmPath, err)
 		return nil
 	}
 	return &wasmWebSocketCallback{
-		wasmBasePlugin: &wasmBasePlugin[api.WebSocketCallback, *api.WebSocketCallbackPlugin]{
-			wasmPath:   wasmPath,
-			id:         pluginID,
-			capability: CapabilityWebSocketCallback,
-			loader:     loader,
-			loadFunc: func(ctx context.Context, l *api.WebSocketCallbackPlugin, path string) (api.WebSocketCallback, error) {
+		wasmBasePlugin: newWasmBasePlugin[api.WebSocketCallback, *api.WebSocketCallbackPlugin](
+			wasmPath,
+			pluginID,
+			CapabilityWebSocketCallback,
+			m.metrics,
+			loader,
+			func(ctx context.Context, l *api.WebSocketCallbackPlugin, path string) (api.WebSocketCallback, error) {
 				return l.Load(ctx, path)
 			},
-		},
+		),
 	}
 }
 

plugins/host_scheduler_test.go

@@ -16,7 +16,7 @@ var _ = Describe("SchedulerService", func() {
 	)
 
 	BeforeEach(func() {
-		manager = createManager(nil)
+		manager = createManager(nil, nil)
 		ss = manager.schedulerService
 	})
 

plugins/host_websocket_test.go

@@ -84,7 +84,7 @@ var _ = Describe("WebSocket Host Service", func() {
 		DeferCleanup(server.Close)
 
 		// Create a new manager and websocket service
-		manager = createManager(nil)
+		manager = createManager(nil, nil)
 		wsService = newWebsocketService(manager)
 	})
 

plugins/manager.go

@@ -20,6 +20,7 @@ import (
 
 	"github.com/navidrome/navidrome/conf"
 	"github.com/navidrome/navidrome/core/agents"
+	"github.com/navidrome/navidrome/core/metrics"
 	"github.com/navidrome/navidrome/core/scrobbler"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
@@ -39,7 +40,7 @@ const (
 )
 
 // pluginCreators maps capability types to their respective creator functions
-type pluginConstructor func(wasmPath, pluginID string, runtime api.WazeroNewRuntime, mc wazero.ModuleConfig) WasmPlugin
+type pluginConstructor func(wasmPath, pluginID string, m *Manager, runtime api.WazeroNewRuntime, mc wazero.ModuleConfig) WasmPlugin
 
 var pluginCreators = map[string]pluginConstructor{
 	CapabilityMetadataAgent:     newWasmMediaAgent,
@@ -95,21 +96,23 @@ type Manager struct {
 	lifecycle        *pluginLifecycleManager        // Manages plugin lifecycle and initialization
 	adapters         map[string]WasmPlugin          // Map of plugin folder name + capability to adapter
 	ds               model.DataStore                // DataStore for accessing persistent data
+	metrics          metrics.Metrics
 }
 
 // GetManager returns the singleton instance of Manager
-func GetManager(ds model.DataStore) *Manager {
+func GetManager(ds model.DataStore, metrics metrics.Metrics) *Manager {
 	return singleton.GetInstance(func() *Manager {
-		return createManager(ds)
+		return createManager(ds, metrics)
 	})
 }
 
 // createManager creates a new Manager instance. Used in tests
-func createManager(ds model.DataStore) *Manager {
+func createManager(ds model.DataStore, metrics metrics.Metrics) *Manager {
 	m := &Manager{
 		plugins:   make(map[string]*plugin),
 		lifecycle: newPluginLifecycleManager(),
 		ds:        ds,
+		metrics:   metrics,
 	}
 
 	// Create the host services
@@ -174,7 +177,7 @@ func (m *Manager) registerPlugin(pluginID, pluginDir, wasmPath string, manifest
 			}
 			continue
 		}
-		adapter := constructor(wasmPath, pluginID, customRuntime, mc)
+		adapter := constructor(wasmPath, pluginID, m, customRuntime, mc)
 		if adapter == nil {
 			log.Error("Failed to create plugin adapter", "plugin", pluginID, "capability", capabilityStr, "path", wasmPath)
 			continue

plugins/manager_test.go

@@ -27,7 +27,7 @@ var _ = Describe("Plugin Manager", func() {
 		conf.Server.Plugins.Folder = testDataDir
 
 		ctx = GinkgoT().Context()
-		mgr = createManager(nil)
+		mgr = createManager(nil, nil)
 		mgr.ScanPlugins()
 	})
 
@@ -85,7 +85,7 @@ var _ = Describe("Plugin Manager", func() {
 			})
 
 			conf.Server.Plugins.Folder = tempPluginsDir
-			m = createManager(nil)
+			m = createManager(nil, nil)
 		})
 
 		// Helper to create a complete valid plugin for manager testing

plugins/manifest_permissions_test.go

@@ -55,7 +55,7 @@ var _ = Describe("Plugin Permissions", func() {
 	BeforeEach(func() {
 		DeferCleanup(configtest.SetupConfig())
 		ctx = context.Background()
-		mgr = createManager(nil)
+		mgr = createManager(nil, nil)
 		tempDir = GinkgoT().TempDir()
 	})
 

plugins/runtime_test.go

@@ -40,7 +40,7 @@ var _ = Describe("CachingRuntime", func() {
 
 	BeforeEach(func() {
 		ctx = GinkgoT().Context()
-		mgr = createManager(nil)
+		mgr = createManager(nil, nil)
 		// Add permissions for the test plugin using typed struct
 		permissions := schema.PluginManifestPermissions{
 			Http: &schema.PluginManifestPermissionsHttp{
@@ -58,6 +58,7 @@ var _ = Describe("CachingRuntime", func() {
 		plugin = newWasmScrobblerPlugin(
 			filepath.Join(testDataDir, "fake_scrobbler", "plugin.wasm"),
 			"fake_scrobbler",
+			mgr,
 			rtFunc,
 			wazero.NewModuleConfig().WithStartFunctions("_initialize"),
 		).(*wasmScrobblerPlugin)

plugins/wasm_base_plugin.go

@@ -2,13 +2,28 @@ package plugins
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"time"
 
+	"github.com/navidrome/navidrome/core/agents"
+	"github.com/navidrome/navidrome/core/metrics"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model/id"
 )
 
+// newWasmBasePlugin creates a new instance of wasmBasePlugin with the required parameters.
+func newWasmBasePlugin[S any, P any](wasmPath, id, capability string, m metrics.Metrics, loader P, loadFunc loaderFunc[S, P]) *wasmBasePlugin[S, P] {
+	return &wasmBasePlugin[S, P]{
+		wasmPath:   wasmPath,
+		id:         id,
+		capability: capability,
+		loader:     loader,
+		loadFunc:   loadFunc,
+		metrics:    m,
+	}
+}
+
 // LoaderFunc is a generic function type that loads a plugin instance.
 type loaderFunc[S any, P any] func(ctx context.Context, loader P, path string) (S, error)
 
@@ -20,6 +35,7 @@ type wasmBasePlugin[S any, P any] struct {
 	capability string
 	loader     P
 	loadFunc   loaderFunc[S, P]
+	metrics    metrics.Metrics
 }
 
 func (w *wasmBasePlugin[S, P]) PluginID() string {
@@ -34,6 +50,10 @@ func (w *wasmBasePlugin[S, P]) serviceName() string {
 	return w.id + "_" + w.capability
 }
 
+func (w *wasmBasePlugin[S, P]) getMetrics() metrics.Metrics {
+	return w.metrics
+}
+
 // getInstance loads a new plugin instance and returns a cleanup function.
 func (w *wasmBasePlugin[S, P]) getInstance(ctx context.Context, methodName string) (S, func(), error) {
 	start := time.Now()
@@ -57,7 +77,9 @@ func (w *wasmBasePlugin[S, P]) getInstance(ctx context.Context, methodName strin
 }
 
 type wasmPlugin[S any] interface {
+	PluginID() string
 	getInstance(ctx context.Context, methodName string) (S, func(), error)
+	getMetrics() metrics.Metrics
 }
 
 type errorMapper interface {
@@ -73,10 +95,25 @@ func callMethod[S any, R any](ctx context.Context, w wasmPlugin[S], methodName s
 	if err != nil {
 		return r, err
 	}
+	start := time.Now()
 	defer done()
 	r, err = fn(inst)
+	elapsed := time.Since(start)
+
 	if em, ok := any(w).(errorMapper); ok {
-		return r, em.mapError(err)
+		mappedErr := em.mapError(err)
+
+		if !errors.Is(mappedErr, agents.ErrNotFound) {
+			id := w.PluginID()
+			isOk := mappedErr == nil
+			metrics := w.getMetrics()
+			if metrics != nil {
+				metrics.RecordPluginRequest(ctx, id, methodName, isOk, elapsed.Milliseconds())
+			}
+			log.Trace(ctx, "callMethod", "plugin", id, "method", methodName, "ok", isOk, elapsed)
+		}
+
+		return r, mappedErr
 	}
 	return r, err
 }