BUG: Fix race between initSignalHandler() and cfgInitOnce()

Configuration gets on first Get() through cfgInitOnce.Do(), however if
any signal gets received during initalization and before
InitWithConfiguration() that initializes logging, log calls will race
with ongoing log initialization. Patch moves cfg.initSignalHandler()
below log.InitWithConfiguration().

Author: dkorunic

cmd/dataplaneapi/main.go

@@ -176,6 +176,8 @@ func startServer(cfg *configuration.Configuration) (reload configuration.AtomicB
 		os.Exit(1)
 	}
 
+	cfg.InitSignalHandler()
+
 	log.Infof("HAProxy Data Plane API %s %s%s", GitTag, GitCommit, GitDirty)
 	log.Infof("Build from: %s", GitRepo)
 	log.Infof("Build date: %s", BuildTime)

configuration/configuration.go

@@ -160,7 +160,6 @@ var (
 func Get() *Configuration {
 	cfgInitOnce.Do(func() {
 		cfg = &Configuration{}
-		cfg.initSignalHandler()
 		cfg.Notify.BootstrapKeyChanged = NewChanNotify()
 		cfg.Notify.ServerStarted = NewChanNotify()
 		cfg.Notify.CertificateRefresh = NewChanNotify()

configuration/signals.go

@@ -80,7 +80,7 @@ func (cn *ChanNotify) notify(numTry int) {
 	}
 }
 
-func (c *Configuration) initSignalHandler() {
+func (c *Configuration) InitSignalHandler() {
 	osSignals := make(chan os.Signal, 1)
 	signal.Notify(osSignals, syscall.SIGINT, syscall.SIGTERM)