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>

server/subsonic/album_lists_test.go

@@ -25,7 +25,7 @@ var _ = Describe("Album Lists", func() {
 	BeforeEach(func() {
 		ds = &tests.MockDataStore{}
 		mockRepo = ds.Album(ctx).(*tests.MockAlbumRepo)
-		router = New(ds, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+		router = New(ds, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
 		w = httptest.NewRecorder()
 	})
 

server/subsonic/api.go

@@ -13,6 +13,7 @@ import (
 	"github.com/navidrome/navidrome/core"
 	"github.com/navidrome/navidrome/core/artwork"
 	"github.com/navidrome/navidrome/core/external"
+	"github.com/navidrome/navidrome/core/metrics"
 	"github.com/navidrome/navidrome/core/playback"
 	"github.com/navidrome/navidrome/core/scrobbler"
 	"github.com/navidrome/navidrome/log"
@@ -43,11 +44,13 @@ type Router struct {
 	scrobbler scrobbler.PlayTracker
 	share     core.Share
 	playback  playback.PlaybackServer
+	metrics   metrics.Metrics
 }
 
 func New(ds model.DataStore, artwork artwork.Artwork, streamer core.MediaStreamer, archiver core.Archiver,
 	players core.Players, provider external.Provider, scanner scanner.Scanner, broker events.Broker,
 	playlists core.Playlists, scrobbler scrobbler.PlayTracker, share core.Share, playback playback.PlaybackServer,
+	metrics metrics.Metrics,
 ) *Router {
 	r := &Router{
 		ds:        ds,
@@ -62,6 +65,7 @@ func New(ds model.DataStore, artwork artwork.Artwork, streamer core.MediaStreame
 		scrobbler: scrobbler,
 		share:     share,
 		playback:  playback,
+		metrics:   metrics,
 	}
 	r.Handler = r.routes()
 	return r
@@ -69,6 +73,11 @@ func New(ds model.DataStore, artwork artwork.Artwork, streamer core.MediaStreame
 
 func (api *Router) routes() http.Handler {
 	r := chi.NewRouter()
+
+	if conf.Server.Prometheus.Enabled {
+		r.Use(recordStats(api.metrics))
+	}
+
 	r.Use(postFormToQueryParams)
 
 	// Public
@@ -223,7 +232,7 @@ func h(r chi.Router, path string, f handler) {
 	})
 }
 
-// Add a Subsonic handler that requires a http.ResponseWriter (ex: stream, getCoverArt...)
+// Add a Subsonic handler that requires an http.ResponseWriter (ex: stream, getCoverArt...)
 func hr(r chi.Router, path string, f handlerRaw) {
 	handle := func(w http.ResponseWriter, r *http.Request) {
 		res, err := f(w, r)

server/subsonic/media_annotation_test.go

@@ -27,7 +27,7 @@ var _ = Describe("MediaAnnotationController", func() {
 		ds = &tests.MockDataStore{}
 		playTracker = &fakePlayTracker{}
 		eventBroker = &fakeEventBroker{}
-		router = New(ds, nil, nil, nil, nil, nil, nil, eventBroker, nil, playTracker, nil, nil)
+		router = New(ds, nil, nil, nil, nil, nil, nil, eventBroker, nil, playTracker, nil, nil, nil)
 	})
 
 	Describe("Scrobble", func() {

server/subsonic/media_retrieval_test.go

@@ -33,7 +33,7 @@ var _ = Describe("MediaRetrievalController", func() {
 			MockedMediaFile: mockRepo,
 		}
 		artwork = &fakeArtwork{data: "image data"}
-		router = New(ds, artwork, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+		router = New(ds, artwork, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
 		w = httptest.NewRecorder()
 		DeferCleanup(configtest.SetupConfig())
 		conf.Server.LyricsPriority = "embedded,.lrc"

server/subsonic/middlewares.go

@@ -11,12 +11,15 @@ import (
 	"net/http"
 	"net/url"
 	"strings"
+	"time"
 
+	"github.com/go-chi/chi/v5/middleware"
 	ua "github.com/mileusna/useragent"
 	"github.com/navidrome/navidrome/conf"
 	"github.com/navidrome/navidrome/consts"
 	"github.com/navidrome/navidrome/core"
 	"github.com/navidrome/navidrome/core/auth"
+	"github.com/navidrome/navidrome/core/metrics"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/request"
@@ -222,3 +225,23 @@ func playerIDCookieName(userName string) string {
 	cookieName := fmt.Sprintf("nd-player-%x", userName)
 	return cookieName
 }
+
+func recordStats(metrics metrics.Metrics) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		fn := func(w http.ResponseWriter, r *http.Request) {
+			ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
+
+			start := time.Now()
+			defer func() {
+				// We want to get the client name (even if not present for certain endpoints)
+				p := req.Params(r)
+				client, _ := p.String("c")
+
+				metrics.RecordRequest(r.Context(), strings.Replace(r.URL.Path, ".view", "", 1), r.Method, client, ww.Status(), time.Since(start).Milliseconds())
+			}()
+
+			next.ServeHTTP(ww, r)
+		}
+		return http.HandlerFunc(fn)
+	}
+}

server/subsonic/opensubsonic_test.go

@@ -19,7 +19,7 @@ var _ = Describe("GetOpenSubsonicExtensions", func() {
 	)
 
 	BeforeEach(func() {
-		router = subsonic.New(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+		router = subsonic.New(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
 		w = httptest.NewRecorder()
 		r = httptest.NewRequest("GET", "/getOpenSubsonicExtensions?f=json", nil)
 	})

server/subsonic/playlists_test.go

@@ -20,7 +20,7 @@ var _ = Describe("UpdatePlaylist", func() {
 	BeforeEach(func() {
 		ds = &tests.MockDataStore{}
 		playlists = &fakePlaylists{}
-		router = New(ds, nil, nil, nil, nil, nil, nil, nil, playlists, nil, nil, nil)
+		router = New(ds, nil, nil, nil, nil, nil, nil, nil, playlists, nil, nil, nil, nil)
 	})
 
 	It("clears the comment when parameter is empty", func() {