DHCP agent fails to configure routed networks due to failure generating subnet options

[Miguel Lavalle]

In a routed networks environment, after the merge of https://review.openstack.org/#/c/468744, the dhcp agent attempts to generate subnet options for both local and non local subnets. If one of the non-local subnets is classified as isolated from the point of view of the metadata service, the following traceback occurs:

Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent [-] Unable to enable dhcp for 40dcd8c6-e4a1-4510-ac62-f37c11e65a5a.: KeyError: u'2cbde018-1c03-40f8-9d67-90a03c7ebd37'
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent Traceback (most recent call last):
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent File "/opt/stack/neutron/neutron/agent/dhcp/agent.py", line 144, in call_driver
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent getattr(driver, action)(**action_kwargs)
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent File "/opt/stack/neutron/neutron/agent/linux/dhcp.py", line 219, in enable
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent self.spawn_process()
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent File "/opt/stack/neutron/neutron/agent/linux/dhcp.py", line 446, in spawn_process
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent self._spawn_or_reload_process(reload_with_HUP=False)
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent File "/opt/stack/neutron/neutron/agent/linux/dhcp.py", line 455, in _spawn_or_reload_process
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent self._output_config_files()
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent File "/opt/stack/neutron/neutron/agent/linux/dhcp.py", line 499, in _output_config_files
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent self._output_opts_file()
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent File "/opt/stack/neutron/neutron/agent/linux/dhcp.py", line 872, in _output_opts_file
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent options, subnet_index_map = self._generate_opts_per_subnet()
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent File "/opt/stack/neutron/neutron/agent/linux/dhcp.py", line 933, in _generate_opts_per_subnet
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent subnet_dhcp_ip and subnet.ip_version == 4):
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent KeyError: u'2cbde018-1c03-40f8-9d67-90a03c7ebd37'
Mar 26 15:21:41 compute2 neutron-dhcp-agent[31181]: ERROR neutron.agent.dhcp.agent

This traceback is due to the fact that the non-local subnet in question has no interface in the DHCP agent namespace, so it is not found when:

subnet_dhcp_ip = subnet_to_interface_ip[subnet.id]

is executed

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/556584

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/556584
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=bb5138cff4e6c383d4d9e902423072a1493832b9
Submitter: Zuul
Branch: master

commit bb5138cff4e6c383d4d9e902423072a1493832b9
Author: Miguel Lavalle <email address hidden>
Date: Mon Mar 26 11:20:18 2018 -0500

    Fix DHCP isolated subnets with routed networks

    After the merge of [1], the DHCP agent will fail to configure a routed
    network when attempting to generate host routes for a non-local subnet
    that is also isolated from the point of view of the metadata service.
    This patch adds a check to make sure that the host route is not added
    for non-local subnets.

    [1] https://review.openstack.org/#/c/468744

    Change-Id: Ia03f538a7d2d10d600d9359da5b3a74532709d1f
    Closes-Bug: #1758952

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 13.0.0.0b1 development milestone.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/queens
Review: https://review.openstack.org/584264

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/584264
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=c7e80a656e3f3b3b103cb2ffed6171d10e6d4cad
Submitter: Zuul
Branch: stable/queens

commit c7e80a656e3f3b3b103cb2ffed6171d10e6d4cad
Author: Miguel Lavalle <email address hidden>
Date: Mon Mar 26 11:20:18 2018 -0500

    Fix DHCP isolated subnets with routed networks

    After the merge of [1], the DHCP agent will fail to configure a routed
    network when attempting to generate host routes for a non-local subnet
    that is also isolated from the point of view of the metadata service.
    This patch adds a check to make sure that the host route is not added
    for non-local subnets.

    [1] https://review.openstack.org/#/c/468744

    Change-Id: Ia03f538a7d2d10d600d9359da5b3a74532709d1f
    Closes-Bug: #1758952
    (cherry picked from commit bb5138cff4e6c383d4d9e902423072a1493832b9)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 12.0.4 release.