cloud-init fails intermittently

Issue

• Upon boot up the cloud-init should complete so that the heat templates can update the hostname, IPs, routes, etc.., but cloud-init fails. The main interface is not configured and the VM can only be reached by the console. This is intermittent, deleting the VM and volumes usually fixes it, but not always. Sometimes 2 or 3 attempts are required.

• The following errors are seen in /var/log/messages:

[root@overcloud-compute-0 ~]# egrep cloud-init /var/log/messages
May 30 00:39:05 overcloud-compute-0 cloud-init[913362]:     if self.datasource and hasattr(self.datasource, 'network_config'):
May 30 00:39:01 overcloud-compute-0 systemd[1]: cloud-init.service: Main process exited, code=exited, status=1/FAILURE
May 30 00:39:09 overcloud-compute-0 cloud-init[913362]:   File "/usr/lib/python3.6/site-packages/cloudinit/sources/DataSourceConfigDrive.py", line 155, in network_config
May 30 00:39:09 overcloud-compute-0 cloud-init[913362]:     self.network_json, known_macs=self.known_macs)
May 30 00:39:09 overcloud-compute-0 cloud-init[913362]:   File "/usr/lib/python3.6/site-packages/cloudinit/sources/helpers/openstack.py", line 669, in convert_net_json
May 30 00:39:09 overcloud-compute-0 cloud-init[913362]:     raise ValueError("Unable to find a system nic for %s" % d)
May 30 00:39:09 overcloud-compute-0 cloud-init[913362]: ValueError: Unable to find a system nic for {'type': 'physical', 'mtu': 9000, 'subnets': [{'type': 'dhcp4'}], 'mac_address': '00:00:00:00:00:20'}