Added Go pprof handlers

Signed-off-by: Fred Heinecke <fred.heinecke@yahoo.com>

transcoder/.env.example

@@ -20,6 +20,12 @@ GOCODER_VAAPI_RENDERER="/dev/dri/renderD128"
 # the qsv device path (only used with GOCODER_HWACCEL=qsv)
 GOCODER_QSV_RENDERER="/dev/dri/renderD128"
 
+# Performance tuning
+# Set to true to enable pprof endpoints for profiling (/debug/pprof/). It is not recommended to expose
+# this to users or the Internet, as this could be used to leak information via a side-channel attack.
+# It is recommended to use a reverse proxy to restrict access to this endpoint, if enabled.
+ENABLE_PPROF_ENDPOINT="false"
+
 # Database things
 # Setting this ignores the below connection variables and overrides any default values
 # POSTGRES_URL=postgres://user:password@host:port/dbname?sslmode=disable

transcoder/main.go

@@ -6,6 +6,7 @@ import (
 	"strconv"
 
 	"github.com/zoriya/kyoo/transcoder/src"
+	"github.com/zoriya/kyoo/transcoder/src/api"
 
 	"github.com/labstack/echo/v4"
 	"github.com/labstack/echo/v4/middleware"
@@ -322,5 +323,7 @@ func main() {
 	g.GET("/:path/attachment/:name", h.GetAttachment)
 	g.GET("/:path/subtitle/:name", h.GetSubtitle)
 
+	api.RegisterPProfHandlers(e)
+
 	e.Logger.Fatal(e.Start(":7666"))
 }

transcoder/src/api/pprof.go

@@ -0,0 +1,60 @@
+package api
+
+import (
+	// Important: simply import the pprof package to register its with a default HTTP mux, if one is defined.
+	// This is done in the init function of the pprof package, and is unavoidable.
+	// This package should not use the default HTTP mux to prevent accidentially enabling these endpoints.
+	"net/http"
+	"net/http/pprof"
+	"os"
+	runtimepprof "runtime/pprof"
+	"strconv"
+
+	"github.com/labstack/echo/v4"
+)
+
+// This is similar to https://github.com/sevennt/echo-pprof/blob/master/pprof.go.
+// Unfortunately, this library is not maintained anymore and doesn't support echo v4.
+// It also hard-codes codes all pprof handlers, which sometimes change when new profiles are added.
+
+func RegisterPProfHandlers(e *echo.Echo) {
+	enablePProf := false
+	if enablePProfVar, ok := os.LookupEnv("ENABLE_PPROF_ENDPOINT"); ok {
+		enablePProf, _ = strconv.ParseBool(enablePProfVar)
+	}
+
+	if !enablePProf {
+		return
+	}
+
+	prefix := "/debug/pprof" // Standard prefix for pprof
+	g := e.Group(prefix)
+
+	routers := map[string]http.HandlerFunc{
+		"":         pprof.Index,
+		"/":        pprof.Index,
+		"/cmdline": pprof.Cmdline,
+		"/profile": pprof.Profile,
+		"/symbol":  pprof.Symbol,
+		"/trace":   pprof.Trace,
+	}
+
+	// Handle all profiles supported by the Go runtime
+	// These are not hard-coded so that this function does not need to be updated
+	// when new profiles are added in the future.
+	for _, profile := range runtimepprof.Profiles() {
+		profileName := profile.Name()
+		path := "/" + profileName
+		routers[path] = pprof.Handler(profileName).ServeHTTP
+	}
+
+	for path, handler := range routers {
+		handler := func(ctx echo.Context) error {
+			handler(ctx.Response().Writer, ctx.Request())
+			return nil
+		}
+
+		// The pprof handlers will accept/reject specific methods if needed.
+		g.Any(path, handler)
+	}
+}