Merge pull request #546 from ryanbreen/master

Add a randomized start before running CheckMonitors.

command/agent/check.go

@@ -93,7 +93,10 @@ func (c *CheckMonitor) Stop() {
 
 // run is invoked by a goroutine to run until Stop() is called
 func (c *CheckMonitor) run() {
-	next := time.After(0)
+	// Get the randomized initial pause time
+	initialPauseTime := randomStagger(c.Interval)
+	c.Logger.Printf("[DEBUG] agent: pausing %v before first invocation of %s", initialPauseTime, c.Script)
+	next := time.After(initialPauseTime)
 	for {
 		select {
 		case <-next:

command/agent/check_test.go

@@ -65,6 +65,34 @@ func TestCheckMonitor_BadCmd(t *testing.T) {
 	expectStatus(t, "foobarbaz", structs.HealthCritical)
 }
 
+func TestCheckMonitor_RandomStagger(t *testing.T) {
+	mock := &MockNotify{
+		state:   make(map[string]string),
+		updates: make(map[string]int),
+		output:  make(map[string]string),
+	}
+	check := &CheckMonitor{
+		Notify:   mock,
+		CheckID:  "foo",
+		Script:   "exit 0",
+		Interval: 25 * time.Millisecond,
+		Logger:   log.New(os.Stderr, "", log.LstdFlags),
+	}
+	check.Start()
+	defer check.Stop()
+
+	time.Sleep(50 * time.Millisecond)
+
+	// Should have at least 1 update
+	if mock.updates["foo"] < 1 {
+		t.Fatalf("should have 1 or more updates %v", mock.updates)
+	}
+
+	if mock.state["foo"] != structs.HealthPassing {
+		t.Fatalf("should be %v %v", structs.HealthPassing, mock.state)
+	}
+}
+
 func TestCheckMonitor_LimitOutput(t *testing.T) {
 	mock := &MockNotify{
 		state:   make(map[string]string),