NM should not be restarted during hostname publish if NM_CONTROLLED=y

azurelinuxagent/common/osutil/redhat.py

@@ -117,11 +117,39 @@ def set_hostname(self, hostname):
             logger.warn("[{0}] failed, attempting fallback".format(' '.join(hostnamectl_cmd)))
             DefaultOSUtil.set_hostname(self, hostname)
 
+    def get_nm_controlled(self):
+        ifname = self.get_if_name()
+        filepath = "/etc/sysconfig/network-scripts/ifcfg-{0}".format(ifname)
+        nm_controlled_cmd = ['grep', 'NM_CONTROLLED=', filepath]
+        try:
+            result = shellutil.run_command(nm_controlled_cmd, log_error=False, encode_output=False).rstrip()
+
+            if result and len(result.split('=')) > 1:
+                # Remove trailing white space and ' or " characters
+                value = result.split('=')[1].replace("'", '').replace('"', '').rstrip()
+                if value == "n" or value == "no":
+                    return False
+        except shellutil.CommandError as e:
+            # Command might fail because NM_CONTROLLED value is not in interface config file (exit code 1).
+            # Log warning for any other exit code.
+            # NM_CONTROLLED=y by default if not specified.
+            if e.returncode != 1:
+                logger.warn("[{0}] failed: {1}.\nAgent will continue to publish hostname without NetworkManager restart".format(' '.join(nm_controlled_cmd), e))
+        except Exception as e:
+            logger.warn("Unexpected error while retrieving value of NM_CONTROLLED in {0}: {1}.\nAgent will continue to publish hostname without NetworkManager restart".format(filepath, e))
+
+        return True
+
     def publish_hostname(self, hostname):
         """
-        Restart NetworkManager first before publishing hostname
+        Restart NetworkManager first before publishing hostname, only if the network interface is not controlled by the
+        NetworkManager service (as determined by NM_CONTROLLED=n in the interface configuration). If the NetworkManager
+        service is restarted before the agent publishes the hostname, and NM_controlled=y, a race condition may happen
+        between the NetworkManager service and the Guest Agent making changes to the network interface configuration
+        simultaneously.
         """
-        shellutil.run("service NetworkManager restart")
+        if not self.get_nm_controlled():
+            shellutil.run("service NetworkManager restart")
         super(RedhatOSUtil, self).publish_hostname(hostname)
 
     def register_agent_service(self):