Tenant cannot delete network when dhcp-agent is running

[Hisaharu Ishii]

dhcp-agent owns port on network and IP address on subnet.
There is no API for tenant to release port and IP adress owned by dhcp-agent.
When tenant requests to delete network or subnet, NetworkInUse or SubnetInUse exeptions must be caused.

[Nachi Ueno (nati-ueno)]

Hi Mark

IMO, a port for DHCP server should be created manually.
Because current DHCP agent creates port automatically, we can't delete network.

How do you think?

[Nachi Ueno (nati-ueno)]

Hi folks

I added analyze here
https://docs.google.com/presentation/d/1QV9rm553SC0IVX62BDH4XFc7-RFNKR2kM-TIHM9lRjI/edit#slide=id.g19a15eaa_0_20

[dan wendlandt (danwent)]

Its pretty important that we deal with this soon. I can see a couple of possibilities:

1) remove check that prevents us from deleting a network when ports are on it.
2) keep the check, but make sure that dhcp-agent tears down the port it creates on the network when there are no other ports on the network (and hence no need for a dhcp server).
3) keep the check, but have some way for DHCP ports to be marked as 'internal' or 'system' ports that should be ignored by the check.

We have a somewhat similar issue with ports created by routers in my L3 + floating IP patch, though in this case at least the tenant does have the ability to delete the port without it being automatically created again.

[Mark McClain (markmcclain)]

I did some work on this bug during lunch.

The DHCP agent listens for notifications and releases the port|fixed_ip when <network|subnet>_delete_start is broadcast. I also tweaked the base plugin to wait 2 seconds before proceeding. This should give the agents time to clean-up properly.

[Nachi Ueno (nati-ueno)]

Hi Mark

Now port has device_owner.
How about his spec?

1) When we delete network, it will be notified to the dhcp server.
quantum server will delete port.

2) When dhcp-agent get notify, it will cleanup port in local

[dan wendlandt (danwent)]

If we don't get this in today, its a must have for RC1

[Akihiro Motoki (amotoki)]

I confirmed that subnet can be deleted even when dhcp server is running
after Mark's patch "Convert DHCP from polling to RPC" (commit 96827953beba575a12acde5377adba95de00690a) is merged
with devstack (with https://review.openstack.org/#/c/11278/).

[Ian Wells (ijw-ubuntu)]

This even happens if there are no subnets assigned to the network.

[Mark McClain (markmcclain)]

@ijw-ubuntu

I've tried to reproduce this bug with an empty network using both bridging and OVS, but cannot. Which plugin are you running?
Can you provide some steps to reproduce?

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/11996

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/11996
Committed: http://github.com/openstack/quantum/commit/88e2551c69739d76a1802838adaae0d244aa5333
Submitter: Jenkins
Branch: master

commit 88e2551c69739d76a1802838adaae0d244aa5333
Author: Mark McClain <email address hidden>
Date: Mon Aug 27 12:04:21 2012 -0400

    fix bug where network owned resources block delete

    bug 1028174

    This patch fixes a bug in delete_network and delete_subnet where the InUse
    exception was being thrown for resources owned by the network and not
    the tenant. This patch force deletes network resources if they are the
    only blocker to deleting the parent resource.

    Change-Id: I822cc4a92cb05cdef88679bb628fad4e5063cddd