dhcp release fails when client_id is specified

[Steve Baker]

Since dhcp_release was migrated to oslo.privsep[1], specifying a client_id results in the command failing because the client_id string is appended to a list, exploding each character into a list item[2].

Here is the error in a CI log[3]:
Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: Stderr: 'usage: dhcp_release <interface> <addr> <mac> [<client_id>]\n' {{(pid=25342) _process_cmd /usr/local/lib/python3.6/dist-packages/oslo_privsep/daemon.py:490}}

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: Traceback (most recent call last):

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: File "/usr/local/lib/python3.6/dist-packages/oslo_privsep/daemon.py", line 485, in _process_cmd

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: ret = func(*f_args, **f_kwargs)

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: File "/usr/local/lib/python3.6/dist-packages/oslo_privsep/priv_context.py", line 249, in _wrap

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: return func(*args, **kwargs)

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: File "/opt/stack/neutron/neutron/privileged/agent/linux/dhcp.py", line 28, in dhcp_release

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: return processutils.execute(*cmd, log_errors=log_errors)

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: File "/usr/local/lib/python3.6/dist-packages/oslo_concurrency/processutils.py", line 434, in execute

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: cmd=sanitized_cmd)

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: oslo_concurrency.processutils.ProcessExecutionError: Unexpected error while running command.

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: Command: ip netns exec qdhcp-5885eb4e-3b5c-48e6-ae40-8a1eeb6629a1 dhcp_release tapa3753962-c7 10.1.0.27 52:54:00:f5:77:63 0 1 : 5 2 : 5 4 : 0 0 : f 5 : 7 7 : 6 3

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: Exit code: 1

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: Stdout: ''

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: Stderr: 'usage: dhcp_release <interface> <addr> <mac> [<client_id>]\n'

Sep 23 16:15:03.221252 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: DEBUG oslo.privsep.daemon [-] privsep: reply[140015332807184]: (5, 'oslo_concurrency.processutils.ProcessExecutionError', ('', 'usage: dhcp_release <interface> <addr> <mac> [<client_id>]\n', 1, 'ip netns exec qdhcp-5885eb4e-3b5c-48e6-ae40-8a1eeb6629a1 dhcp_release tapa3753962-c7 10.1.0.27 52:54:00:f5:77:63 0 1 : 5 2 : 5 4 : 0 0 : f 5 : 7 7 : 6 3', None)) {{(pid=25342) _call_back /usr/local/lib/python3.6/dist-packages/oslo_privsep/daemon.py:511}}

Sep 23 16:15:03.227555 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: WARNING neutron.agent.linux.dhcp [-] DHCP release failed for params {'interface_name': 'tapa3753962-c7', 'ip_address': '10.1.0.27', 'mac_address': '52:54:00:f5:77:63', 'client_id': '01:52:54:00:f5:77:63', 'namespace': 'qdhcp-5885eb4e-3b5c-48e6-ae40-8a1eeb6629a1'}. Reason: Unexpected error while running command.

Sep 23 16:15:03.227555 ubuntu-bionic-rax-ord-0019993612 neutron-dhcp-agent[11285]: Command: ip netns exec qdhcp-5885eb4e-3b5c-48e6-ae40-8a1eeb6629a1 dhcp_release tapa3753962-c7 10.1.0.27 52:54:00:f5:77:63 0 1 : 5 2 : 5 4 : 0 0 : f 5 : 7 7 : 6 3

[1] https://review.opendev.org/#/c/733864
[2] https://opendev.org/openstack/neutron/src/branch/master/neutron/privileged/agent/linux/dhcp.py#L26
[3] https://zuul.opendev.org/t/openstack/build/ee0efe9616b04dc384aa3f4d0ca62168/log/controller/logs/screen-q-dhcp.txt#4142

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/753865

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/753865
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=2864957ca53a346418f89cc945bba5cdcf204799
Submitter: Zuul
Branch: master

commit 2864957ca53a346418f89cc945bba5cdcf204799
Author: Steve Baker <email address hidden>
Date: Thu Sep 24 11:58:05 2020 +1200

    Fix dhcp_release when client_id is specified

    Appending a string to a list results in each character being appended
    as list items, this results in an invalid release command.

    This change appends the client_id string to the list instead.

    Change-Id: I71a114308e3b68f6daf6e1a202a47b6a453bb81a
    Closes-Bug: #1896850

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/victoria
Review: https://review.opendev.org/755817

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/755817
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=0562335908f177c53f0dec307e9414f928a38892
Submitter: Zuul
Branch: stable/victoria

commit 0562335908f177c53f0dec307e9414f928a38892
Author: Steve Baker <email address hidden>
Date: Thu Sep 24 11:58:05 2020 +1200

    Fix dhcp_release when client_id is specified

    Appending a string to a list results in each character being appended
    as list items, this results in an invalid release command.

    This change appends the client_id string to the list instead.

    Change-Id: I71a114308e3b68f6daf6e1a202a47b6a453bb81a
    Closes-Bug: #1896850
    (cherry picked from commit 2864957ca53a346418f89cc945bba5cdcf204799)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 18.0.0.0rc1 release candidate.