Fix sync bug

@@ -147,6 +147,19 @@ class EMRClusterScanner(object):
             return False
         else:
             return True
+
+    def checkDNS(self):
+        check_cmd = 'ansible-playbook -i {0} {1} --check'.format(self.inventoryFile,self.playbook_resolv)
+        execute_cmd = 'ansible-playbook -i {0} {1}'.format(self.inventoryFile,self.playbook_resolv)
+        output = os.popen(check_cmd).read()
+        if 'changed=1' in output:
+            print '检测到未变更主机!'
+            print '开始执行变更'
+            os.popen(execute_cmd)
+        else:
+            print '主机配置已最新'
+        return True
+        
     
     def updateEMRInventory(self, emrName):
         #比对当前与最新的Inventory ip列表，相同则pass不同则更新
@@ -182,6 +195,9 @@ class EMRClusterScanner(object):
                 print 'Running playbook to sync DNS...'
                 syncResult = self.syncDNS(emrName)
                 if syncResult:
+                print 'Running playbook to sync DNS...'
+                syncResult = self.syncDNS(emrName)
+                if syncResult:
                     print 'DNS synced'
                 else:
                     print 'DNS sync failed'
@@ -192,6 +208,7 @@ class EMRClusterScanner(object):
     def start_daemon(self):
         #以守护进程的状态运行此EMR扫描程序
         while True:
+            self.checkDNS()
             for emrName in self.emrNameMap:
                 try:
                     result = self.updateEMRInventory(emrName)