DHCP timeout when creating instances for specific tenants

Grant Morley grant at civo.com
Thu Dec 5 11:38:36 UTC 2019

Hi all,

It looks like the issue was actually with the Ubuntu image for both 
16.04 and 18.04. We changed the dhcp timeout in 
"/etc/dhcp/dhclient.conf" from 300 seconds down to 2 seconds and the 
instances then worked absolutely fine. Not sure why it was only 
happening for some tenants and not others but that has resolved it.

I am still going to look into the metadata service as the fix doesn't 
feel right to me still.

Thanks again for all your help.


On 05/12/2019 00:09, Laurent Dumont wrote:
> Maybe the following could provide a bit more data :
>   * Launch a test instance in the tenant project experiencing the issue.
>   * tcpdump directly on the instance TAP interface - confirm if you
>   * Would also allow you to see the Cloudinit traffic.
> On Wed, Dec 4, 2019 at 7:06 PM Grant Morley <grant at civo.com 
> <mailto:grant at civo.com>> wrote:
>     Hi Cory,
>     Thanks for the response. I'll take a look at the metadata service
>     from the instance and from OpenStack itself tomorrow now. It's
>     midnight here in the UK and I need to get some rest. Thanks for
>     the tip, hopefully I'll find something useful to go on from there.
>     Grant,
>     On 04/12/2019 23:49, Cory Hawkless wrote:
>>     Are they failing to contact the metadata service and hanging
>>     during the boot process while they try and receive metadata?
>>     From the VM can you hit – That’s the
>>     default IP of the metadata server, it should respond with a basic
>>     page showing some date based subdirectories
>>     If it doesn’t respond you can start following the metadata
>>     service path instead of DHCP
>>     Given that the machines come up with an IP eventually leads me to
>>     think the DHCP service is actually working ok.
>>     *From:*Grant Morley [mailto:grant at civo.com]
>>     *Sent:* Thursday, 5 December 2019 10:10 AM
>>     *To:* Eric K. Miller <emiller at genesishosting.com>
>>     <mailto:emiller at genesishosting.com>;
>>     openstack-operators at lists.openstack.org
>>     <mailto:openstack-operators at lists.openstack.org>
>>     *Cc:* Ian Banks <ian at civo.com> <mailto:ian at civo.com>
>>     *Subject:* Re: DHCP timeout when creating instances for specific
>>     tenants
>>     Hi Eric,
>>     Thanks for getting back to me. I am fairly sure it is a DHCP
>>     error. The instances are getting an IP when they eventually boot,
>>     it is just taking a long time for them to bring up networking.
>>     The strange thing is, it only seems to be new tenants. All
>>     existing tenants are absolutely fine.
>>     I can check DNS as well just to be on the safe side, however I
>>     wasn't seeing any errors in the Nova or Neutron logs when the
>>     instance(s) were being created.
>>     Regards,
>>     On 04/12/2019 22:47, Eric K. Miller wrote:
>>         Hi Grant,
>>         Are you sure this is a DHCP timeout and not a DNS resolution
>>         issue?  I ask because we have seen a strange DNS issue occur
>>         that can cause something similar.
>>         Are the VMs being assigned an IP after they finally boot?
>>         Eric K. Miller
>>         Genesis Hosting Solutions, LLC
>>         Try our Genesis Public Cloud - powered by OpenStack!eut
>>         https://genesishosting.com/
>>         *From:*Grant Morley [mailto:grant at civo.com]
>>         *Sent:* Wednesday, December 04, 2019 11:00 AM
>>         *To:* openstack-operators at lists.openstack.org
>>         <mailto:openstack-operators at lists.openstack.org>
>>         *Cc:* Ian Banks
>>         *Subject:* DHCP timeout when creating instances for specific
>>         tenants
>>         Hi all,
>>         I wonder if anyone can help shed any light on an odd issue we
>>         are seeing with only a couple of specific tenants. Basically
>>         if they launch an instance they are taking about 5 minutes to
>>         launch rather than our usual 30 second or so launch.
>>         We are seeing the following on the instance logs:
>>         https://pastebin.com/hDstsd8G
>>         Weirdly it only seems to be happening for 1 or 2 new tenants.
>>         I have tested this on our personal account and a few other
>>         customers have tested and their instances launch really
>>         quickly as expected.
>>         Is there anything specific during the tenant creation that
>>         can cause this issue? Or are there any logs in nova / neutron
>>         I should be looking out for that might shed some light?
>>         I haven't seen anything that is obvious. Any help would be
>>         much appreciated as we are a little stumped at the moment.
>>         Many thanks,
>>         -- 
>>         Grant Morley
>>         Cloud Lead, Civo Ltd
>>         www.civo.com <https://www.civo.com/>| Signup for an account!
>>         <https://www.civo.com/signup>

Grant Morley
Cloud Lead, Civo Ltd
www.civo.com <https://www.civo.com/>| Signup for an account! 
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