feat: Expose pprof endpoints in debug mode (#2503)

* feat: Expose pprof endpoints in debug mode

* Adding documentation

* fix linter issue

* Change port

---------

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

cmd/relayproxy/api/routes_monitoring.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"github.com/labstack/echo-contrib/echoprometheus"
+	"github.com/labstack/echo-contrib/pprof"
 	"github.com/labstack/echo/v4"
 	"github.com/labstack/echo/v4/middleware"
 	custommiddleware "github.com/thomaspoignant/go-feature-flag/cmd/relayproxy/api/middleware"
@@ -39,4 +40,8 @@ func (s *Server) initMonitoringEndpoint(echoInstance *echo.Echo) {
 	// health Routes
 	echoInstance.GET("/health", cHealth.Handler)
 	echoInstance.GET("/info", cInfo.Handler)
+
+	if s.config.Debug {
+		pprof.Register(echoInstance)
+	}
 }

cmd/relayproxy/api/routes_monitoring_test.go

@@ -0,0 +1,79 @@
+package api_test
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/thomaspoignant/go-feature-flag/cmd/relayproxy/api"
+	"github.com/thomaspoignant/go-feature-flag/cmd/relayproxy/config"
+	"github.com/thomaspoignant/go-feature-flag/cmd/relayproxy/metric"
+	"github.com/thomaspoignant/go-feature-flag/cmd/relayproxy/service"
+	"github.com/thomaspoignant/go-feature-flag/notifier"
+	"go.uber.org/zap"
+)
+
+func TestPprofEndpointsStarts(t *testing.T) {
+	type test struct {
+		name               string
+		MonitoringPort     int
+		Debug              bool
+		expectedStatusCode int
+	}
+	tests := []test{
+		{
+			name:               "pprof available in proxy port",
+			Debug:              true,
+			expectedStatusCode: http.StatusOK,
+		},
+		{
+			name:               "pprof available in monitoring port",
+			Debug:              true,
+			MonitoringPort:     1032,
+			expectedStatusCode: http.StatusOK,
+		},
+		{
+			name:               "pprof not available ii debug not enabled",
+			Debug:              false,
+			MonitoringPort:     1032,
+			expectedStatusCode: http.StatusNotFound,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			z, err := zap.NewProduction()
+			require.NoError(t, err)
+			c := &config.Config{
+				Retriever: &config.RetrieverConf{
+					Kind: "file",
+					Path: "../../../testdata/flag-config.yaml",
+				},
+				MonitoringPort: tt.MonitoringPort,
+				ListenPort:     1031,
+				Debug:          tt.Debug,
+			}
+
+			goff, err := service.NewGoFeatureFlagClient(c, z, []notifier.Notifier{})
+			require.NoError(t, err)
+			apiServer := api.New(c, service.Services{
+				MonitoringService:    service.NewMonitoring(goff),
+				WebsocketService:     service.NewWebsocketService(),
+				GOFeatureFlagService: goff,
+				Metrics:              metric.Metrics{},
+			}, z)
+
+			portToCheck := c.ListenPort
+			if tt.MonitoringPort != 0 {
+				portToCheck = tt.MonitoringPort
+			}
+
+			go apiServer.Start()
+			defer apiServer.Stop()
+			resp, err := http.Get(fmt.Sprintf("http://localhost:%d/debug/pprof/heap", portToCheck))
+			require.NoError(t, err)
+			require.Equal(t, tt.expectedStatusCode, resp.StatusCode)
+		})
+	}
+}

cmd/relayproxy/config/config.go

@@ -146,7 +146,9 @@ type Config struct {
 	// HideBanner (optional) if true, we don't display the go-feature-flag relay proxy banner
 	HideBanner bool `mapstructure:"hideBanner" koanf:"hidebanner"`
 
-	// Debug (optional) if true, go-feature-flag relay proxy will run on debug mode, with more logs and custom responses
+	// Debug (optional) if true, go-feature-flag relay proxy will run on debug mode, with more logs and custom responses.
+	// It will also start the pprof endpoints on the same port as the monitoring.
+	// Default: false
 	Debug bool `mapstructure:"debug" koanf:"debug"`
 
 	// EnableSwagger (optional) to have access to the swagger

cmd/relayproxy/docs/docs.go

@@ -63,6 +63,26 @@ const docTemplate = `{
                 }
             }
         },
+        "/debug/pprof/": {
+            "get": {
+                "description": "This endpoint is provided by the echo pprof middleware.\nTo know more please check this blogpost from the GO team https://go.dev/blog/pprof.\nVisit the page /debug/pprof/ to see the available endpoints, all endpoint are not in the swagger documentation because they are standard pprof endpoints.\nThis endpoint is only available in debug mode.",
+                "produces": [
+                    "text/plain"
+                ],
+                "tags": [
+                    "Profiling"
+                ],
+                "summary": "pprof endpoint",
+                "responses": {
+                    "200": {
+                        "description": "OK",
+                        "schema": {
+                            "type": "string"
+                        }
+                    }
+                }
+            }
+        },
         "/health": {
             "get": {
                 "description": "Making a **GET** request to the URL path ` + "`" + `/health` + "`" + ` will tell you if the relay proxy is ready to serve\ntraffic.\n\nThis is useful especially for loadbalancer to know that they can send traffic to the service.",

cmd/relayproxy/docs/swagger.json

@@ -55,6 +55,26 @@
                 }
             }
         },
+        "/debug/pprof/": {
+            "get": {
+                "description": "This endpoint is provided by the echo pprof middleware.\nTo know more please check this blogpost from the GO team https://go.dev/blog/pprof.\nVisit the page /debug/pprof/ to see the available endpoints, all endpoint are not in the swagger documentation because they are standard pprof endpoints.\nThis endpoint is only available in debug mode.",
+                "produces": [
+                    "text/plain"
+                ],
+                "tags": [
+                    "Profiling"
+                ],
+                "summary": "pprof endpoint",
+                "responses": {
+                    "200": {
+                        "description": "OK",
+                        "schema": {
+                            "type": "string"
+                        }
+                    }
+                }
+            }
+        },
         "/health": {
             "get": {
                 "description": "Making a **GET** request to the URL path `/health` will tell you if the relay proxy is ready to serve\ntraffic.\n\nThis is useful especially for loadbalancer to know that they can send traffic to the service.",

cmd/relayproxy/docs/swagger.yaml

@@ -444,6 +444,23 @@ paths:
       summary: This endpoint is used to force the refresh of the flags in the cache.
       tags:
       - Admin API to manage GO Feature Flag
+  /debug/pprof/:
+    get:
+      description: |-
+        This endpoint is provided by the echo pprof middleware.
+        To know more please check this blogpost from the GO team https://go.dev/blog/pprof.
+        Visit the page /debug/pprof/ to see the available endpoints, all endpoint are not in the swagger documentation because they are standard pprof endpoints.
+        This endpoint is only available in debug mode.
+      produces:
+      - text/plain
+      responses:
+        "200":
+          description: OK
+          schema:
+            type: string
+      summary: pprof endpoint
+      tags:
+      - Profiling
   /health:
     get:
       description: |-

cmd/relayproxy/modeldocs/metricsController.go

@@ -2,7 +2,7 @@ package modeldocs
 
 import "github.com/labstack/echo/v4"
 
-// FakeMetricsController is the entry point for the allFlags endpoint
+// FakeMetricsController is a fake entry point for swagger documentation
 //
 // @Summary      Prometheus endpoint
 // @Tags Monitoring

cmd/relayproxy/modeldocs/pprofController.go

@@ -0,0 +1,19 @@
+// nolint: lll
+package modeldocs
+
+import "github.com/labstack/echo/v4"
+
+// FakePprofController is a fake endpoint for swagger documentation of pprof endpoint
+//
+// @Summary      pprof endpoint
+// @Tags Profiling
+// @Description  This endpoint is provided by the echo pprof middleware.
+// @Description  To know more please check this blogpost from the GO team https://go.dev/blog/pprof.
+// @Description  Visit the page /debug/pprof/ to see the available endpoints, all endpoint are not in the swagger documentation because they are standard pprof endpoints.
+// @Description  This endpoint is only available in debug mode.
+// @Produce      plain
+// @Success      200 {object}	string
+// @Router       /debug/pprof/ [get]
+func FakePprofController(_ echo.Context) {
+	// This is a fake controller, the real entry point is provided by the prometheus middleware.
+}

website/docs/relay_proxy/profiling.md

@@ -0,0 +1,32 @@
+---
+sidebar_position: 81
+title: Profiling
+description: Profiling of the relay proxy.
+---
+
+## Profiling
+
+The **relay proxy** is able to expose profiling information.  
+This is useful to understand the performance of the service and solve potential issues.
+
+The information are exposed on the `/debug/pprof` endpoint, and we are using the default `net/http/pprof` package
+to expose the information.
+
+:::warning
+By default the profiling endpoints are disabled.  
+You have to run the relay proxy in debug mode if you want to enable them.
+:::
+
+List of endpoints exposed is available http://localhost:1031/debug/pprof/
+
+### Enable profiling
+
+In your relay proxy configuration file you need to set the `debug` field to `true`.
+
+```yaml {5}
+retriever:
+  kind: file
+  path: /goff/flags.yaml # Location of your feature flag files
+#  ...
+debug: true
+```