feat: Prometheus metrics

.gitignore

@@ -18,6 +18,7 @@ server/src/coverage.txt
 build
 server/src/main
 server/src/server
+server/src/tmp
 
 # misc
 .DS_Store

server/config_example.toml

@@ -75,3 +75,6 @@ disable-check-origin = true
 
 # Specify the URL for the feedback webhook.
 feedback-webhook-url = ""
+
+# Enable metrics for the backend server
+enable-metrics = true

server/docker-compose.dev.yml

@@ -16,3 +16,23 @@ services:
       - POSTGRES_PASSWORD=supersecret
       - POSTGRES_DB=scrumlr
       - POSTGRES_INITDB_ARGS=--encoding=UTF-8 --lc-collate=C --lc-ctype=C
+
+  prometheus:
+    image: prom/prometheus:v2.52.0
+    ports:
+      - 9090:9090
+    volumes:
+      - ./prometheus.yml:/etc/prometheus/prometheus.yml
+    command: --config.file=/etc/prometheus/prometheus.yml
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
+
+  grafana:
+    image: grafana/grafana:10.4.2
+    ports:
+      - 3001:3000
+    environment:
+      - GF_SECURITY_ADMIN_USER=test
+      - GF_SECURITY_ADMIN_PASSWORD=test
+    volumes:
+      - ./grafana.yml:/etc/grafana/provisioning/datasources/datasources.yml

server/grafana.yml

@@ -0,0 +1,6 @@
+apiVersion: 1
+datasources: 
+- name: Main
+  type: prometheus
+  url: http://prometheus:9090
+  isDefault: true

server/prometheus.yml

@@ -0,0 +1,15 @@
+global:
+  scrape_interval:     15s # By default, scrape targets every 15 seconds.
+
+scrape_configs:
+  - job_name: 'scrumlr-api'
+
+    # Override the global default and scrape targets from this job every 5 seconds.
+    scrape_interval: 5s
+    scrape_timeout: 5s
+    metrics_path: /metrics
+    scheme: http
+    follow_redirects: true
+
+    static_configs:
+      - targets: ['host.docker.internal:8080']

server/src/api/metrics.go

@@ -0,0 +1,79 @@
+package api
+
+import (
+	"context"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/go-chi/chi/middleware"
+	"github.com/prometheus/client_golang/prometheus"
+	"scrumlr.io/server/logger"
+)
+
+var (
+	endpointLatency = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "http_request_duration_seconds",
+			Help:    "HTTP request latency per endpoint.",
+			Buckets: []float64{0.1, 0.2, 0.5, 1, 3, 5, 10},
+		},
+		[]string{"method", "route", "status"},
+	)
+	requestCounter = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "http_request_counter",
+			Help: "Counter of HTTP requests",
+		}, []string{"method", "route", "status"},
+	)
+)
+
+func (s *Server) initMetrics() {
+	log := logger.FromContext(context.Background())
+	err := s.customMetrics.RegisterCounterVec(requestCounter)
+	if err != nil {
+		log.Errorw("unable to register counter for custom metrics", err)
+	}
+	err = s.customMetrics.RegisterHistogramVec(endpointLatency)
+	if err != nil {
+		log.Errorw("unable to register histogram for custom metrics", err)
+	}
+}
+
+func metricCounterMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
+		defer func() {
+			urlPath := generalizeURLPath(r.URL.Path)
+			requestCounter.WithLabelValues(r.Method, urlPath, strconv.Itoa(ww.Status())).Inc()
+		}()
+		next.ServeHTTP(ww, r)
+
+	})
+}
+
+func metricMeasureLatencyMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
+		defer func() {
+			duration := time.Since(start).Seconds()
+			urlPath := generalizeURLPath(r.URL.Path)
+			endpointLatency.WithLabelValues(r.Method, urlPath, strconv.Itoa(ww.Status())).Observe(duration)
+		}()
+		next.ServeHTTP(ww, r)
+
+	})
+}
+
+// Replaces UUID-like segments with a wildcard placeholder
+func generalizeURLPath(path string) string {
+	segments := strings.Split(path, "/")
+	for i, segment := range segments {
+		if len(segment) == 36 && strings.Contains(segment, "-") {
+			segments[i] = "*"
+		}
+	}
+	return strings.Join(segments, "/")
+}

server/src/api/notes.go

@@ -2,9 +2,10 @@ package api
 
 import (
 	"fmt"
+	"net/http"
+
 	"github.com/go-chi/render"
 	"github.com/google/uuid"
-	"net/http"
 	"scrumlr.io/server/common"
 	"scrumlr.io/server/common/dto"
 	"scrumlr.io/server/identifiers"

server/src/api/router.go

@@ -10,6 +10,7 @@ import (
 	"github.com/go-chi/render"
 	"github.com/google/uuid"
 	"github.com/gorilla/websocket"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 
 	"scrumlr.io/server/auth"
 	"scrumlr.io/server/logger"
@@ -36,6 +37,8 @@ type Server struct {
 	feedback       services.Feedback
 	boardReactions services.BoardReactions
 	boardTemplates services.BoardTemplates
+	customMetrics  services.CustomMetrics
+
 
 	upgrader websocket.Upgrader
 
@@ -61,7 +64,7 @@ func New(
 	feedback services.Feedback,
 	boardReactions services.BoardReactions,
 	boardTemplates services.BoardTemplates,
-
+	customMetrics services.CustomMetrics,
 	verbose bool,
 	checkOrigin bool,
 	anonymousLoginDisabled bool,
@@ -71,6 +74,8 @@ func New(
 	r.Use(middleware.RequestID)
 	r.Use(logger.RequestIDMiddleware)
 	r.Use(render.SetContentType(render.ContentTypeJSON))
+	r.Use(metricCounterMiddleware)
+	r.Use(metricMeasureLatencyMiddleware)
 
 	if !checkOrigin {
 		r.Use(cors.Handler(cors.Options{
@@ -105,7 +110,7 @@ func New(
 		feedback:                         feedback,
 		boardReactions:                   boardReactions,
 		boardTemplates:                   boardTemplates,
-
+		customMetrics:                    customMetrics,
 		anonymousLoginDisabled: anonymousLoginDisabled,
 	}
 
@@ -115,6 +120,11 @@ func New(
 		WriteBufferSize: 1024,
 	}
 
+	// Registers needed metrics for prometheus
+	if s.customMetrics != nil {
+		s.initMetrics()
+	}
+
 	if checkOrigin {
 		s.upgrader.CheckOrigin = nil
 	} else {
@@ -148,6 +158,7 @@ func (s *Server) publicRoutes(r chi.Router) chi.Router {
 				r.Get("/callback", s.verifyAuthProviderCallback)
 			})
 		})
+		s.initCustomMetricResources(r)
 	})
 }
 
@@ -332,3 +343,12 @@ func (s *Server) initBoardReactionResources(r chi.Router) {
 		r.Post("/", s.createBoardReaction)
 	})
 }
+
+func (s *Server) initCustomMetricResources(r chi.Router) {
+	if s.customMetrics != nil {
+		r.Handle("/metrics", promhttp.HandlerFor(
+			s.customMetrics.Registry(),
+			promhttp.HandlerOpts{Registry: s.customMetrics.Registry()},
+		))
+	}
+}

server/src/go.mod

@@ -6,6 +6,7 @@ go 1.22
 replace github.com/opencontainers/runc v1.1.0 => github.com/opencontainers/runc v1.1.2
 
 require (
+	github.com/go-chi/chi v1.5.5
 	github.com/go-chi/chi/v5 v5.1.0
 	github.com/go-chi/cors v1.2.1
 	github.com/go-chi/httprate v0.12.0
@@ -20,6 +21,7 @@ require (
 	github.com/nats-io/nats.go v1.36.0
 	github.com/ory/dockertest/v3 v3.10.0
 	github.com/pkg/errors v0.9.1
+	github.com/prometheus/client_golang v1.19.1
 	github.com/stretchr/testify v1.9.0
 	github.com/uptrace/bun v1.1.17
 	github.com/uptrace/bun/dbfixture v1.1.17
@@ -39,6 +41,7 @@ require (
 	github.com/Microsoft/go-winio v0.6.1 // indirect
 	github.com/Nvveen/Gotty v0.0.0-20120604004816-cd527374f1e5 // indirect
 	github.com/ajg/form v1.5.1 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cenkalti/backoff/v4 v4.1.3 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/containerd/continuity v0.3.0 // indirect
@@ -83,6 +86,9 @@ require (
 	github.com/opencontainers/image-spec v1.0.2 // indirect
 	github.com/opencontainers/runc v1.1.12 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_model v0.5.0 // indirect
+	github.com/prometheus/common v0.48.0 // indirect
+	github.com/prometheus/procfs v0.12.0 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
 	github.com/segmentio/asm v1.2.0 // indirect
 	github.com/sirupsen/logrus v1.9.2 // indirect

server/src/go.sum

@@ -14,6 +14,8 @@ github.com/Nvveen/Gotty v0.0.0-20120604004816-cd527374f1e5/go.mod h1:lmUJ/7eu/Q8
 github.com/ProtonMail/go-crypto v0.0.0-20230217124315-7d5c6f04bbb8/go.mod h1:I0gYDMZ6Z5GRU7l58bNFSkPTFN6Yl12dsUlAZ8xy98g=
 github.com/ajg/form v1.5.1 h1:t9c7v8JUKu/XxOGBU0yjNpaMloxGEJhUkqFRq0ibGeU=
 github.com/ajg/form v1.5.1/go.mod h1:uL1WgH+h2mgNtvBq0339dVnzXdBETtL2LeUXaIv25UY=
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/bwesterb/go-ristretto v1.2.0/go.mod h1:fUIoIZaG73pV5biE2Blr2xEzDoMj7NFEuV9ekS419A0=
 github.com/cenkalti/backoff/v4 v4.1.3 h1:cFAlzYUlVYDysBEH2T5hyJZMh3+5+WCBvSnK6Q8UtC4=
 github.com/cenkalti/backoff/v4 v4.1.3/go.mod h1:scbssz8iZGpm3xbr14ovlUdkxfGXNInqkPWOWmG2CLw=
@@ -52,6 +54,8 @@ github.com/fatih/color v1.16.0/go.mod h1:fL2Sau1YI5c0pdGEVCbKQbLXB6edEj1ZgiY4Nij
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/fsnotify/fsnotify v1.4.9 h1:hsms1Qyu0jgnwNXIxa+/V/PDsU6CfLf6CNO8H7IWoS4=
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
+github.com/go-chi/chi v1.5.5 h1:vOB/HbEMt9QqBqErz07QehcOKHaWFtuj87tTDVz2qXE=
+github.com/go-chi/chi v1.5.5/go.mod h1:C9JqLr3tIYjDOZpzn+BCuxY8z8vmca43EeMgyZt7irw=
 github.com/go-chi/chi/v5 v5.1.0 h1:acVI1TYaD+hhedDJ3r54HyA6sExp3HfXq7QWEEY/xMw=
 github.com/go-chi/chi/v5 v5.1.0/go.mod h1:DslCQbL2OYiznFReuXYUmQ2hGd1aDpCnlMNITLSKoi8=
 github.com/go-chi/cors v1.2.1 h1:xEC8UT3Rlp2QuWNEr4Fs/c2EAGVKBwy/1vHx3bppil4=
@@ -180,6 +184,14 @@ github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/prometheus/client_golang v1.19.1 h1:wZWJDwK+NameRJuPGDhlnFgx8e8HN3XHQeLaYJFJBOE=
+github.com/prometheus/client_golang v1.19.1/go.mod h1:mP78NwGzrVks5S2H6ab8+ZZGJLZUq1hoULYBAYBw1Ho=
+github.com/prometheus/client_model v0.5.0 h1:VQw1hfvPvk3Uv6Qf29VrPF32JB6rtbgI6cYPYQjL0Qw=
+github.com/prometheus/client_model v0.5.0/go.mod h1:dTiFglRmd66nLR9Pv9f0mZi7B7fk5Pm3gvsjB5tr+kI=
+github.com/prometheus/common v0.48.0 h1:QO8U2CdOzSn1BBsmXJXduaaW+dY/5QLjfB8svtSzKKE=
+github.com/prometheus/common v0.48.0/go.mod h1:0/KsvlIEfPQCQ5I2iNSAWKPZziNCvRs5EC6ILDTlAPc=
+github.com/prometheus/procfs v0.12.0 h1:jluTpSng7V9hY0O2R9DzzJHYb2xULk9VTR1V1R/k6Bo=
+github.com/prometheus/procfs v0.12.0/go.mod h1:pcuDEFsWDnvcgNzo4EEweacyhjeA9Zk3cnaOZAZEfOo=
 github.com/rogpeppe/go-internal v1.12.0 h1:exVL4IDcn6na9z1rAb56Vxr+CgyK3nn3O+epU5NdKM8=
 github.com/rogpeppe/go-internal v1.12.0/go.mod h1:E+RYuTGaKKdloAfM02xzb0FW3Paa99yedzYV+kq4uf4=
 github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=

server/src/main.go

@@ -8,6 +8,8 @@ import (
 	"strings"
 
 	"scrumlr.io/server/auth"
+	"scrumlr.io/server/services"
+	"scrumlr.io/server/services/custom_metrics"
 	"scrumlr.io/server/services/health"
 
 	"scrumlr.io/server/api"
@@ -206,6 +208,13 @@ func main() {
 				Usage:    "TOML `filepath` to be loaded ",
 				Required: false,
 			},
+			altsrc.NewBoolFlag(&cli.BoolFlag{
+				Name:     "enable-metrics",
+				Aliases:  []string{"m"},
+				EnvVars:  []string{"ENABLE_SCRUMLR_METRICS"},
+				Usage:    "enables metrics and its endpoint",
+				Required: false,
+			}),
 		},
 	}
 	app.Before = altsrc.InitInputSourceWithContext(app.Flags, altsrc.NewTomlSourceFromFlagFunc("config"))
@@ -296,6 +305,12 @@ func run(c *cli.Context) error {
 			RedirectUri:  fmt.Sprintf("%s%s/login/apple/callback", strings.TrimSuffix(c.String("auth-callback-host"), "/"), strings.TrimSuffix(basePath, "/")),
 		}
 	}
+	var customMetricService services.CustomMetrics
+	if c.IsSet("enable-metrics") {
+		customMetricService = custom_metrics.NewCustomMetricService(true)
+	} else {
+		customMetricService = nil
+	}
 
 	dbConnection := database.New(db, c.Bool("verbose"))
 
@@ -329,7 +344,7 @@ func run(c *cli.Context) error {
 		feedbackService,
 		boardReactionService,
 		boardTemplateService,
-
+		customMetricService,
 		c.Bool("verbose"),
 		!c.Bool("disable-check-origin"),
 		c.Bool("disable-anonymous-login"),

server/src/services/custom_metrics/metrics.go

@@ -0,0 +1,34 @@
+package custom_metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
+	"scrumlr.io/server/services"
+)
+
+type CustomMetricService struct {
+	registry prometheus.Registry
+}
+
+func NewCustomMetricService(enabled bool) services.CustomMetrics {
+	if enabled {
+		m := &CustomMetricService{}
+		m.registry = *prometheus.NewRegistry()
+		m.registry.Unregister(collectors.NewGoCollector()) // Unregister the default bloat of metrics
+		return m
+	}
+
+	return nil
+}
+
+func (cms *CustomMetricService) RegisterHistogramVec(histo *prometheus.HistogramVec) error {
+	return cms.registry.Register(histo)
+}
+
+func (cms *CustomMetricService) RegisterCounterVec(ctr *prometheus.CounterVec) error {
+	return cms.registry.Register(ctr)
+}
+
+func (cms *CustomMetricService) Registry() *prometheus.Registry {
+	return &cms.registry
+}

server/src/services/services.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"github.com/google/uuid"
+	"github.com/prometheus/client_golang/prometheus"
 	"scrumlr.io/server/common/dto"
 	"scrumlr.io/server/common/filter"
 )
@@ -114,3 +115,9 @@ type BoardTemplates interface {
 	UpdateColumnTemplate(ctx context.Context, body dto.ColumnTemplateUpdateRequest) (*dto.ColumnTemplate, error)
 	DeleteColumnTemplate(ctx context.Context, boar, column, user uuid.UUID) error
 }
+
+type CustomMetrics interface {
+	RegisterHistogramVec(hist *prometheus.HistogramVec) error
+	RegisterCounterVec(ctr *prometheus.CounterVec) error
+	Registry() *prometheus.Registry
+}