cmd/coordinator: disable Kubernetes mode in local "dev" mode

Restore the local "dev" mode after the refactor in CL 422956.
The development environment doesn't have KubeServices set to
anything, so KubeServices.Location() was otherwise panicking.

While here, also do fewer things in background of "dev" mode
unless appropriate dev flags are turned on.

For golang/go#65913.

Change-Id: Ib7409c28e39f2dbf98e08a4bcbd21cd45cb81aa1
Reviewed-on: https://go-review.googlesource.com/c/build/+/567496
Reviewed-by: Dmitri Shuralyov <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>
Auto-Submit: Dmitri Shuralyov <[email protected]>

Author: dmitshur

cmd/coordinator/coordinator.go

@@ -247,16 +247,20 @@ func main() {
 
 	gce := pool.NewGCEConfiguration()
 
-	goKubeClient, err := gke.NewClient(context.Background(),
-		gce.BuildEnv().KubeServices.Name,
-		gce.BuildEnv().KubeServices.Location(),
-		gke.OptNamespace(gce.BuildEnv().KubeServices.Namespace),
-		gke.OptProject(gce.BuildEnv().ProjectName),
-		gke.OptTokenSource(gce.GCPCredentials().TokenSource))
-	if err != nil {
-		log.Fatalf("connecting to GKE failed: %v", err)
+	if gce.BuildEnv().KubeServices.Name != "" {
+		goKubeClient, err := gke.NewClient(context.Background(),
+			gce.BuildEnv().KubeServices.Name,
+			gce.BuildEnv().KubeServices.Location(),
+			gke.OptNamespace(gce.BuildEnv().KubeServices.Namespace),
+			gke.OptProject(gce.BuildEnv().ProjectName),
+			gke.OptTokenSource(gce.GCPCredentials().TokenSource))
+		if err != nil {
+			log.Fatalf("connecting to GKE failed: %v", err)
+		}
+		go monitorGitMirror(goKubeClient)
+	} else {
+		log.Println("Kubernetes services disabled due to empty KubeServices.Name")
 	}
-	go monitorGitMirror(goKubeClient)
 
 	if *mode == "prod" || (*mode == "dev" && *devEnableEC2) {
 		// TODO(golang.org/issues/38337) the coordinator will use a package scoped pool
@@ -364,7 +368,9 @@ func main() {
 	if *mode == "dev" {
 		// TODO(crawshaw): do more in dev mode
 		gce.BuildletPool().SetEnabled(*devEnableGCE)
-		go findWorkLoop()
+		if *devEnableGCE || *devEnableEC2 {
+			go findWorkLoop()
+		}
 	} else {
 		go gce.BuildletPool().CleanUpOldVMs()