metrics: add paths_readers metric (#4473) (#4789)

README.md

@@ -2135,6 +2135,7 @@ Obtaining:
 paths{name="[path_name]",state="[state]"} 1
 paths_bytes_received{name="[path_name]",state="[state]"} 1234
 paths_bytes_sent{name="[path_name]",state="[state]"} 1234
+paths_readers{name="[path_name]",state="[state]"} 1234
 
 # metrics of every HLS muxer
 hls_muxers{name="[name]"} 1

internal/core/metrics_test.go

@@ -336,21 +336,27 @@ webrtc_sessions_bytes_sent 0
 			`^paths\{name=".*?",state="ready"\} 1`+"\n"+
 				`paths_bytes_received\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths_bytes_sent\{name=".*?",state="ready"\} [0-9]+`+"\n"+
+				`paths_readers\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths\{name=".*?",state="ready"\} 1`+"\n"+
 				`paths_bytes_received\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths_bytes_sent\{name=".*?",state="ready"\} [0-9]+`+"\n"+
+				`paths_readers\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths\{name=".*?",state="ready"\} 1`+"\n"+
 				`paths_bytes_received\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths_bytes_sent\{name=".*?",state="ready"\} [0-9]+`+"\n"+
+				`paths_readers\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths\{name=".*?",state="ready"\} 1`+"\n"+
 				`paths_bytes_received\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths_bytes_sent\{name=".*?",state="ready"\} [0-9]+`+"\n"+
+				`paths_readers\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths\{name=".*?",state="ready"\} 1`+"\n"+
 				`paths_bytes_received\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths_bytes_sent\{name=".*?",state="ready"\} [0-9]+`+"\n"+
+				`paths_readers\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths\{name=".*?",state="ready"\} 1`+"\n"+
 				`paths_bytes_received\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`paths_bytes_sent\{name=".*?",state="ready"\} [0-9]+`+"\n"+
+				`paths_readers\{name=".*?",state="ready"\} [0-9]+`+"\n"+
 				`hls_muxers\{name=".*?"\} 1`+"\n"+
 				`hls_muxers_bytes_sent\{name=".*?"\} 0`+"\n"+
 				`hls_muxers\{name=".*?"\} 1`+"\n"+

internal/metrics/metrics.go

@@ -162,6 +162,7 @@ func (m *Metrics) onMetrics(ctx *gin.Context) {
 			out += metric("paths", tags, 1)
 			out += metric("paths_bytes_received", tags, int64(i.BytesReceived))
 			out += metric("paths_bytes_sent", tags, int64(i.BytesSent))
+			out += metric("paths_readers", tags, int64(len(i.Readers)))
 		}
 	} else {
 		out += metric("paths", "", 0)

internal/metrics/metrics_test.go

@@ -7,21 +7,58 @@ import (
 	"time"
 
 	"github.com/bluenviron/mediamtx/internal/conf"
+	"github.com/bluenviron/mediamtx/internal/defs"
 	"github.com/bluenviron/mediamtx/internal/test"
 	"github.com/stretchr/testify/require"
 )
 
+func timePtr(t time.Time) *time.Time {
+	return &t
+}
+
+type dummyPathManager struct{}
+
+func (dummyPathManager) APIPathsList() (*defs.APIPathList, error) {
+	return &defs.APIPathList{
+		ItemCount: 20,
+		PageCount: 1,
+		Items: []*defs.APIPath{{
+			Name:     "mypath",
+			ConfName: "mypathconf",
+			Source: &defs.APIPathSourceOrReader{
+				Type: "testing",
+				ID:   "123324354",
+			},
+			Ready:         true,
+			ReadyTime:     timePtr(time.Date(2003, 11, 4, 23, 15, 7, 0, time.UTC)),
+			Tracks:        []string{"H264", "H265"},
+			BytesReceived: 123,
+			BytesSent:     456,
+			Readers: []defs.APIPathSourceOrReader{
+				{
+					Type: "testing",
+					ID:   "345234423",
+				},
+			},
+		}},
+	}, nil
+}
+
+func (dummyPathManager) APIPathsGet(string) (*defs.APIPath, error) {
+	panic("unused")
+}
+
 func TestPreflightRequest(t *testing.T) {
-	api := Metrics{
+	m := Metrics{
 		Address:     "localhost:9998",
 		AllowOrigin: "*",
 		ReadTimeout: conf.Duration(10 * time.Second),
 		AuthManager: test.NilAuthManager,
 		Parent:      test.NilLogger,
 	}
-	err := api.Initialize()
+	err := m.Initialize()
 	require.NoError(t, err)
-	defer api.Close()
+	defer m.Close()
 
 	tr := &http.Transport{}
 	defer tr.CloseIdleConnections()
@@ -47,3 +84,36 @@ func TestPreflightRequest(t *testing.T) {
 	require.Equal(t, "Authorization", res.Header.Get("Access-Control-Allow-Headers"))
 	require.Equal(t, byts, []byte{})
 }
+
+func TestMetrics(t *testing.T) {
+	m := Metrics{
+		Address:     "localhost:9998",
+		AllowOrigin: "*",
+		ReadTimeout: conf.Duration(10 * time.Second),
+		AuthManager: test.NilAuthManager,
+		Parent:      test.NilLogger,
+	}
+	err := m.Initialize()
+	require.NoError(t, err)
+	defer m.Close()
+
+	m.SetPathManager(&dummyPathManager{})
+
+	tr := &http.Transport{}
+	defer tr.CloseIdleConnections()
+	hc := &http.Client{Transport: tr}
+
+	res, err := hc.Get("http://localhost:9998/metrics")
+	require.NoError(t, err)
+	defer res.Body.Close()
+
+	byts, err := io.ReadAll(res.Body)
+	require.NoError(t, err)
+
+	require.Equal(t,
+		`paths{name="mypath",state="ready"} 1`+"\n"+
+			`paths_bytes_received{name="mypath",state="ready"} 123`+"\n"+
+			`paths_bytes_sent{name="mypath",state="ready"} 456`+"\n"+
+			`paths_readers{name="mypath",state="ready"} 1`+"\n",
+		string(byts))
+}