Sometimes instances launch with more than one IP

asked 2016-11-15 13:12:24 -0500

xdaxdb gravatar image

Sometimes when I launch an instance it will show as having more than one IP. When I log in to the instance it only has one interface, eth0 (and lo) and there is only one IP address configured on it. The second IP address is nowhere to be found inside the instance, I only see it on the dashboard.

It seems like this becomes more common when launching multiple instances at the same time, but I have had it happen when launching a single instance too.

What could cause this? I can't find any error messages, presumably because the instance launched successfully.

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answered 2016-11-16 09:20:32 -0500

eblock gravatar image

From my experience, this happened when an instance was about to fail or the first attempt to boot happened on a "wrong" hypervisor. I have two (xen) hypervisors and if I tried to launch an instance from an image without correct properties, I could see that nova tried to launch that instance on both hypervisors. But sometimes the instance booted successfully and Horizon showed two ip addresses, but I also could find only one of them within the instance. If the instance launched successfully, you can simply detach the wrong interface/address via Horizon. It's no real explanation, just sharing my experience.

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It was funny I was looking at the instance from the "admin" view and didn't see an option to remove interfaces. I was able to just remove it from the "project" view. Simple.

xdaxdb gravatar imagexdaxdb ( 2016-11-16 13:53:18 -0500 )edit

answered 2016-11-15 22:19:28 -0500

i had this occur when i had a few different things going on:

try checking your plugin configurations (openvswitch) try ensuring dhcp is not running on your physical versus what's running in openstack.

I know I had conflicting ip addresses / multiple addresses when i had a provider network with dhcp enabled and colliding dhcp scopes with physical network and openstack

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Asked: 2016-11-15 13:12:24 -0500

Seen: 200 times

Last updated: Nov 16 '16