[Openstack-operators] [openstack-dev][openstack-operators][neutron[dhcp][dnsmask]: duplicate entries in addn_hosts causing no IP allocation

Neil Jerram Neil.Jerram at metaswitch.com
Mon Jun 8 16:53:13 UTC 2015


My team has seen a problem that could be related: in a churn test where 
VMs are created and terminated at a constant rate - but so that the 
number of active VMs should remain roughly constant - the size of the 
host and addn_hosts files keeps increasing.

In other words, it appears that the config for VMs that have actually 
been terminated is not being removed from the config file.  Clearly, if 
you have a limited pool of IP addresses, this can eventually lead to the 
problem that you have described.

For your case - i.e. with Icehouse - the problem might be 
https://bugs.launchpad.net/neutron/+bug/1192381.  I'm not sure if the 
fix for that problem - i.e. sending port-create and port-delete 
notifications to DHCP agents even when the server thinks they are down - 
was merged before the Icehouse release, or not.

But there must be at least one other cause as well, because my team was 
seeing this with Juno-level code.

Therefore I, too, would be interested in any other insights about this 
problem.

Regards,
	Neil



On 08/06/15 16:26, Daniel Comnea wrote:
> Any help, ideas please?
>
> Thx,
> Dani
>
> On Mon, Jun 8, 2015 at 9:25 AM, Daniel Comnea <comnea.dani at gmail.com
> <mailto:comnea.dani at gmail.com>> wrote:
>
>     + Operators
>
>     Much thanks in advance,
>     Dani
>
>
>
>
>     On Sun, Jun 7, 2015 at 6:31 PM, Daniel Comnea <comnea.dani at gmail.com
>     <mailto:comnea.dani at gmail.com>> wrote:
>
>         Hi all,
>
>         I'm running IceHouse (build using Fuel 5.1.1) on Ubuntu where
>         dnsmask version 2.59-4.
>         I have a very basic network layout where i have a private net
>         which has 2 subnets
>
>           2fb7de9d-d6df-481f-acca-2f7860cffa60 | private-net
>                                     |
>         e79c3477-d3e5-471c-a728-8d881cf31bee 192.168.110.0/24
>         <http://192.168.110.0/24> |
>         |
>         |                                                         |
>         f48c3223-8507-455c-9c13-8b727ea5f441 192.168.111.0/24
>         <http://192.168.111.0/24> |
>
>         and i'm creating VMs via HEAT.
>         What is happening is that sometimes i get duplicated entries in
>         [1] and because of that the VM which was spun up doesn't get an ip.
>         The Dnsmask processes are running okay [2] and i can't see
>         anything special/ wrong in it.
>
>         Any idea why this is happening? Or are you aware of any bugs
>         around this area? Do you see a problems with having 2 subnets
>         mapped to 1 private-net?
>
>
>
>         Thanks,
>         Dani
>
>         [1]
>         /var/lib/neutron/dhcp/2fb7de9d-d6df-481f-acca-2f7860cffa60/addn_hosts
>
>         [2]
>
>         nobody    5664     1  0 Jun02 ?        00:00:08 dnsmasq
>         --no-hosts --no-resolv --strict-order --bind-interfaces
>         --interface=tapc9164734-0c --except-interface=lo
>         --pid-file=/var/lib/neutron/dhcp/2fb7de9d-d6df-481f-acca-2f7860cffa60/pid
>         --dhcp-hostsfile=/var/lib/neutron/dhcp/2fb7de9d-d6df-481f-acca-2f7860cffa60/host
>         --addn-hosts=/var/lib/neutron/dhcp/2fb7de9d-d6df-481f-acca-2f7860cffa60/addn_hosts
>         --dhcp-optsfile=/var/lib/neutron/dhcp/2fb7de9d-d6df-481f-acca-2f7860cffa60/opts
>         --leasefile-ro --dhcp-authoritative
>         --dhcp-range=set:tag0,192.168.110.0,static,86400s
>         --dhcp-range=set:tag1,192.168.111.0,static,86400s
>         --dhcp-lease-max=512 --conf-file= --server=10.0.0.31
>         --server=10.0.0.32 --domain=openstacklocal
>
>
>
>
>
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