start the pprof based on an env variable in debug builds, otherwise remove the flag/release.go stuff

src/yggdrasil/debug.go

@@ -20,6 +20,20 @@ import "regexp"
 import _ "net/http/pprof"
 import "net/http"
 import "runtime"
+import "os"
+
+// Start the profiler in debug builds, if the required environment variable is set.
+func init() {
+	envVarName := "PPROFLISTEN"
+	hostPort := os.Getenv(envVarName)
+	switch {
+	case hostPort == "":
+		fmt.Printf("DEBUG: %s not set, profiler not started.\n", envVarName)
+	default:
+		fmt.Printf("DEBUG: Starting pprof on %s\n", hostPort)
+		go func() { fmt.Println(http.ListenAndServe(hostPort, nil)) }()
+	}
+}
 
 // Starts the function profiler. This is only supported when built with
 // '-tags build'.

src/yggdrasil/release.go

@@ -1,14 +0,0 @@
-// +build !debug
-
-package yggdrasil
-
-import (
-	"errors"
-	"log"
-)
-
-// Starts the function profiler. This is only supported when built with
-// '-tags build'.
-func StartProfiler(_ *log.Logger) error {
-	return errors.New("Release builds do not support -pprof, build using '-tags debug'")
-}