2 dnsmasq processes. Is it a concern?

Asked by Kenneth Jiang on 2011-12-09

My nova installation is working fine but I'm quite bothered by an observation: there are always 2 dnsmasq processes running at the same time, one being the sub-process of the other:

# ps -ef | grep dns
nobody 11435 1 0 06:09 ? 00:00:00 dnsmasq --strict-order --bind-interfaces --conf-file= --domain=novalocal --pid-file=/var/lib/nova/networks/nova-br100.pid --listen-address=172.16.0.4 --except-interface=lo --dhcp-range=172.16.0.3,static,120s --dhcp-lease-max=256 --dhcp-hostsfile=/var/lib/nova/networks/nova-br100.conf --dhcp-script=/usr/bin/nova-dhcpbridge --leasefile-ro
root 11436 11435 0 06:09 ? 00:00:00 dnsmasq --strict-order --bind-interfaces --conf-file= --domain=novalocal --pid-file=/var/lib/nova/networks/nova-br100.pid --listen-address=172.16.0.4 --except-interface=lo --dhcp-range=172.16.0.3,static,120s --dhcp-lease-max=256 --dhcp-hostsfile=/var/lib/nova/networks/nova-br100.conf --dhcp-script=/usr/bin/nova-dhcpbridge --leasefile-ro

I tried "killall dnsmasq; service nova-network restart" numerous times and the observation remained.

Nova admin guide states this as a problem that will prevent VMs from receiving IP addresses. I also experienced failed DHCP handshake with a Windows VM which I suspect is related with 2 dnsmasq proceses (see my previous question: https://answers.launchpad.net/nova/+question/167297).

So my questions are:
- Is it possible that 2 dnsmasq processes will cause sporadic DHCP handshake failure?
- If so, what can I do to fix it?

Again your help is highly appreciated!
Kenneth

Question information

Language:
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Status:
Solved
For:
OpenStack Compute (nova) Edit question
Assignee:
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Solved by:
Vish Ishaya
Solved:
2011-12-09
Last query:
2011-12-09
Last reply:
2011-12-09
Best Vish Ishaya (vishvananda) said : #1

There are always 2 processes running for each dhcp network. The subprocess is because dnsmasq setuids to nobocy to run the external script specified in --dhcp-script. This is expected behavior. You may run into issues if you have another dnsmasq processes running on the box, such as the one that is started by default if you apt-get install dnsmasq

On Dec 9, 2011, at 6:25 AM, Tianchen Jiang wrote:

> New question #181398 on OpenStack Compute (nova):
> https://answers.launchpad.net/nova/+question/181398
>
> My nova installation is working fine but I'm quite bothered by an observation: there are always 2 dnsmasq processes running at the same time, one being the sub-process of the other:
>
> # ps -ef | grep dns
> nobody 11435 1 0 06:09 ? 00:00:00 dnsmasq --strict-order --bind-interfaces --conf-file= --domain=novalocal --pid-file=/var/lib/nova/networks/nova-br100.pid --listen-address=172.16.0.4 --except-interface=lo --dhcp-range=172.16.0.3,static,120s --dhcp-lease-max=256 --dhcp-hostsfile=/var/lib/nova/networks/nova-br100.conf --dhcp-script=/usr/bin/nova-dhcpbridge --leasefile-ro
> root 11436 11435 0 06:09 ? 00:00:00 dnsmasq --strict-order --bind-interfaces --conf-file= --domain=novalocal --pid-file=/var/lib/nova/networks/nova-br100.pid --listen-address=172.16.0.4 --except-interface=lo --dhcp-range=172.16.0.3,static,120s --dhcp-lease-max=256 --dhcp-hostsfile=/var/lib/nova/networks/nova-br100.conf --dhcp-script=/usr/bin/nova-dhcpbridge --leasefile-ro
>
> I tried "killall dnsmasq; service nova-network restart" numerous times and the observation remained.
>
> Nova admin guide states this as a problem that will prevent VMs from receiving IP addresses. I also experienced failed DHCP handshake with a Windows VM which I suspect is related with 2 dnsmasq proceses (see my previous question: https://answers.launchpad.net/nova/+question/167297).
>
> So my questions are:
> - Is it possible that 2 dnsmasq processes will cause sporadic DHCP handshake failure?
> - If so, what can I do to fix it?
>
> Again your help is highly appreciated!
> Kenneth
>
> --
> You received this question notification because you are a member of Nova
> Core, which is an answer contact for OpenStack Compute (nova).

Kenneth Jiang (kenneth-jiang) said : #2

Thanks Vish Ishaya, that solved my question.