multi: add pprof

This commit adds a config option that can be set inorder to spin up a
pprof profile server on the given port.

aperture.go

@@ -37,6 +37,9 @@ import (
 	"google.golang.org/grpc/keepalive"
 	"google.golang.org/protobuf/encoding/protojson"
 	"gopkg.in/yaml.v2"
+
+	// Blank import to set up profiling HTTP handlers.
+	_ "net/http/pprof"
 )
 
 const (
@@ -185,6 +188,27 @@ func (a *Aperture) Start(errChan chan error) error {
 			"exporter: %v", err)
 	}
 
+	// Enable http profiling and validate profile port number if requested.
+	if a.cfg.ProfilePort != 0 {
+		if a.cfg.ProfilePort < 1024 || a.cfg.ProfilePort > 65535 {
+			return fmt.Errorf("the profile port must be between " +
+				"1024 and 65535")
+		}
+
+		go func() {
+			http.Handle("/", http.RedirectHandler(
+				"/debug/pprof", http.StatusSeeOther,
+			))
+
+			listenAddr := fmt.Sprintf(
+				"localhost:%d", a.cfg.ProfilePort,
+			)
+
+			log.Infof("Starting profile server at %s", listenAddr)
+			fmt.Println(http.ListenAndServe(listenAddr, nil))
+		}()
+	}
+
 	// Initialize our etcd client.
 	a.etcdClient, err = clientv3.New(clientv3.Config{
 		Endpoints:   []string{a.cfg.Etcd.Host},

config.go

@@ -125,6 +125,9 @@ type Config struct {
 
 	// BaseDir is a custom directory to store all aperture flies.
 	BaseDir string `long:"basedir" description:"Directory to place all of aperture's files in."`
+
+	// ProfilePort is the port on which the pprof profile will be served.
+	ProfilePort uint16 `long:"profile" description:"Enable HTTP profiling on given port -- NOTE port must be between 1024 and 65535"`
 }
 
 func (c *Config) validate() error {

sample-conf.yaml

@@ -19,6 +19,10 @@ debuglevel: "debug"
 autocert: false
 servername: aperture.example.com
 
+# The port on which the pprof profile will be served. If no port is provided,
+# the profile will not be served.
+profile: 9999
+
 # Settings for the lnd node used to generate payment requests. All of these
 # options are required.
 authenticator: