Network creation does not notify DHCP agent

[Gary Kotton]

When a new network is created, and the scheduling for the DHCP networks is supported, then DHCP agent is not selected (this would only happen if the DHCP agent was restarted).

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/27705

[yong sheng gong (gongysh)]

hi, this is by design!

[yong sheng gong (gongysh)]

when port is created, we will schedule the network auto. the design provides the administrator a chance to do scheduling manually between the network is created and the port is created.

[Gary Kotton (garyk)]

Thanks for the clarifications. This is not a bug!

[Assaf Muller (amuller)]

Since the DHCP agent isn't notified of network creation, but only of port creation, the first VM that boots on a network may fail to receive a DHCP response.

This is because of an inherent race between the VM booting and the port create notification reaching the DHCP agent (And notification processing time).

If the issue is a matter of manual scheduling - Isn't the admin capable of manually scheduling a network on a DHCP agent when it is created? If so, why not? Isn't that the better solution?

[Maru Newby (maru)]

Assaf: I would seem that the delay in agent scheduling would make dhcp configuration only slightly slower (because dnsmasq would have to be started instead of just SIGHUP'd). Given that, should fixing agent scheduling be a priority over ensuring that vm boot does not proceed until dhcp configuration is complete (via some kind of sync at vif plug)?