Wednesday, September 11, 2013

How to determine the specific DHCP agent assigned to a Quantum/Neutron network in OpenStack

This is a quick post to remind me how to figure out which DHCP agent is assigned to a specific subnet in OpenStack. These steps aren't specific to a version but do expect that namespaces are being used.

SSH to the server hosting the OpenStack DHCP agent service. Make sure you either source a credentials file OR you add the required authentication arguments to the commands.
Using the Quantum or Neutron CLI query for list of networks and filter for the IP network the DHCP agent is assigned.

quantum net-list | grep 192.168.20.0
| 384ab6b5-202a-454e-972b-0e0fadecd58b | test-mgmt | 20bcb936-c033-4e4d-bd08-e54e6a54312b 192.168.20.0/24 | 

Copy the first octet of characters, in this case they are 384ab6b5.

To locate the DHCP agent's name query the Linux namespaces on the network node and filter on the character string you copied to the clipboard.
ip netns | grep 384ab6b5
qdhcp-384ab6b5-202a-454e-972b-0e0fadecd58b