cpud: add an option to sleep before serving

When cpud runs as init, and serves mDNS, it can start serving before
mDNS will work. It is still not clear why this fails, but adding a
5 second sleep before serve() resolves it for now. Such a sleep
is obviously undesirable, but the default is 0.

To set the timeout when cpud runs as init, add -- --sleepBeforeServing=5s
to the kernel command line.

Signed-off-by: Ronald G Minnich <[email protected]>

cmds/cpud/main_linux.go

@@ -36,6 +36,11 @@ var (
 	registerAddr = flag.String("register", "", "address and port to register with after listen on cpu server port")
 	registerTO   = flag.Duration("registerTO", time.Duration(5*time.Second), "time.Duration for Dial address for registering")
 
+	// if we start up too quickly, mDNS won't work correctly.
+	// This sleep may be useful for other cases, so it is here,
+	// not specifically for mDNS uses.
+	sleepBeforeServing = flag.Duration("sleepBeforeServing", 0, "add a sleep before serving -- usually only needed if cpud runs as init with mDNS")
+
 	pid1 bool
 )
 
@@ -89,9 +94,10 @@ func main() {
 			log.Fatal(err)
 		}
 	}
-	pid1 = os.Getpid() == 1
+	pid := os.Getpid()
+	pid1 = pid == 1
 	*runAsInit = *runAsInit || pid1
-	verbose("Args %v pid %d *runasinit %v *remote %v env %v", os.Args, os.Getpid(), *runAsInit, *remote, os.Environ())
+	verbose("Args %v pid %d *runasinit %v *remote %v env %v", os.Args, pid, *runAsInit, *remote, os.Environ())
 	args := flag.Args()
 	if *remote {
 		verbose("args %q, port9p %v", args, *port9p)
@@ -110,12 +116,14 @@ func main() {
 			log.Fatalf("CPUD(remote): %v", err)
 		}
 	} else {
-		log.Printf("CPUD:running as a server (a.k.a. starter of cpud's for sessions)")
+		log.Printf("CPUD:PID(%d):running as a server (a.k.a. starter of cpud's for sessions)", pid)
 		if *runAsInit {
+			log.Printf("CPUD:also running as init")
 			if err := initsetup(); err != nil {
 				log.Fatal(err)
 			}
 		}
+		time.Sleep(*sleepBeforeServing)
 		if err := serve(os.Args[0]); err != nil {
 			log.Fatal(err)
 		}