reject start and create early if grid unstable

Signed-off-by: Jeff Carr <jcarr@wit.com>

create.go

@@ -42,6 +42,15 @@ func create(w http.ResponseWriter, r *http.Request) (string, error) {
 	log.Info("Got msg:", string(msg))
 	log.Info("hostname =", d.Hostname)
 	name := d.Hostname
+
+	// don't continue past here if the grid is unstable anyway
+	// because this will add the droplet to cluster.Droplets
+	if s, err := isClusterStable(); err != nil {
+		log.Info(s)
+		fmt.Fprintln(w, s)
+		return s, err
+	}
+
 	tmpd := findDroplet(name)
 	if tmpd != nil {
 		result := "create error: Droplet " + name + " is already defined"

start.go

@@ -14,11 +14,29 @@ import (
 	pb "go.wit.com/lib/protobuf/virtbuf"
 )
 
+func isClusterStable() (string, error) {
+	// how long has the cluster been stable?
+	// wait until it is stable. use this to throttle droplet starts
+	dur := time.Since(me.unstable)
+	good := fmt.Sprintln("trying to start droplet here. grid stable for: ", shell.FormatDuration(dur))
+	if dur < me.unstableTimeout {
+		tmp := shell.FormatDuration(me.unstableTimeout)
+		err := "grid is still too unstable (unstable timeout = " + tmp + ")\n"
+		return good + err, errors.New(err)
+	}
+	return good, nil
+}
+
 // for now, because sometimes this should write to stdout and
 // sometimes to http socket, it returns a string
 func Start(name string) (string, error) {
 	var result string
 
+	if s, err := isClusterStable(); err != nil {
+		result += s
+		return result, err
+	}
+
 	// lookup the droplet by name
 	d := findDroplet(name)
 	if d == nil {
@@ -38,16 +56,6 @@ func Start(name string) (string, error) {
 		return result, errors.New(result)
 	}
 
-	// how long has the cluster been stable?
-	// wait until it is stable. use this to throttle droplet starts
-	dur := time.Since(me.unstable)
-	result = fmt.Sprintln("should start droplet", name, "here. grid stable for:", shell.FormatDuration(dur))
-	if dur < me.unstableTimeout {
-		tmp := shell.FormatDuration(me.unstableTimeout)
-		result += "grid is still too unstable (unstable timeout = " + tmp + ")"
-		return result, errors.New("grid is still unstable")
-	}
-
 	// make the list of hypervisors that are active and can start new droplets
 	var pool []*HyperT
 	for _, h := range me.hypers {