[Openstack-operators] RHEL 7 / CentOS 7 instances losing their network gateway

Kris G. Lindgren klindgren at godaddy.com
Tue Jan 27 16:25:32 UTC 2015

I can't help as we use config-drive to set networking and are just starting to roll out Cent7 vm's.  However, a huge change from Cent6 to Cent7 was the switch from upstart/dhclient to systemd/systemd-dhcp.

Kris Lindgren
Senior Linux Systems Engineer
GoDaddy, LLC.

From: Joe Topjian <joe at topjian.net<mailto:joe at topjian.net>>
Date: Tuesday, January 27, 2015 at 9:08 AM
To: "openstack-operators at lists.openstack.org<mailto:openstack-operators at lists.openstack.org>" <openstack-operators at lists.openstack.org<mailto:openstack-operators at lists.openstack.org>>
Subject: [Openstack-operators] RHEL 7 / CentOS 7 instances losing their network gateway


I have run into two different OpenStack clouds where instances running either RHEL 7 or CentOS 7 images are randomly losing their network gateway.

There's nothing in the logs that show any indication of why. There's no DHCP hiccup or anything like that. The gateway has just disappeared.

If I log into the instance via another instance (so on the same subnet since there's no gateway), I can manually re-add the gateway and everything works... until it loses it again.

One cloud is running Havana and the other is running Icehouse. Both are using nova-network and both are Ubuntu 12.04.

On the Havana cloud, we decided to install the dnsmasq package from Ubuntu 14.04. This looks to have resolved the issue as this was back in November and I haven't heard an update since.

However, we don't want to do that just yet on the Icehouse cloud. We'd like to understand exactly why this is happening and why updating dnsmasq resolves an issue that only one specific type of image is having.

I can make my way around CentOS, but I'm not as familiar with it as I am with Ubuntu (especially CentOS 7). Does anyone know what change in RHEL7/CentOS7 might be causing this? Or does anyone have any other ideas on how to troubleshoot the issue?

I currently have access to two instances in this state, so I'd be happy to act as remote hands and eyes. :)

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