[Openstack] Guest VM IP configuration script
Van Leeuwen, Robert
rovanleeuwen at ebay.com
Wed Aug 31 06:15:06 UTC 2016
On 8/30/16, 4:44 PM, "Satish Patel" <satish.txt at gmail.com> wrote:
> I didn't find any related configuration which blacklist mac address on
> Mitaka. also i didn't find any document stated that DHCP agent only
> gives ip address to instance mac address.
I am not sure if there is any specific doc about this on the OpenStack pages.
However, neutron starts a dnsmasq process so you can have a look with ps on how that is running and configured.
I am no dnsmasq expert but I looking at the dnsmasq man page:
“The optional <mode> keyword may be static which tells dnsmasq to enable DHCP for the network specified, but not to dynamically allocate IP addresses: only hosts which have static addresses given via dhcp-host or from /etc/ethers will be served”
When you look at the dnsmasq process on a neutron server it is indeed set to static and uses the –dhcp-host options:
dnsmasq --dhcp-range=set:tag0,126.96.36.199,static,5529600s --dhcp-hostsfile=/var/lib/neutron/dhcp/123-4567/host --lots_of_other_options
Last time I had this scenario it was 2 years ago so my memory could be deceiving me but this was also the behavior I experienced.
(Not 100% sure but I think we did have a custom build dnsmasq because the centos 6 version did not support all the required options or something.
Since it was at a previous job I can no longer check but I am pretty sure it worked with 2 dhcp servers in the same range.
Although it also depends a bit on which DHCP responds quicker on what behavior you will see exactly. In theory our “LAN” dhcp just could have been consistently quicker)
Robert van Leeuwen
More information about the Openstack