Disabling IPv6 on an interface fails if IPv6 is completely disabled in the kernel

[Adrien Cunin]

Neutron Mitaka.

From linuxbridge-agent.log:

ERROR neutron.agent.linux.ip_lib [req-7d62c8de-1678-4b17-b568-b2a9a938c97c - - - - -] Failed running ['sysctl', '-w', u'net.ipv6.conf.brqc766b4dc-d2.disable_ipv6=1']
ERROR neutron.agent.linux.ip_lib Traceback (most recent call last):
ERROR neutron.agent.linux.ip_lib File "/usr/lib/python2.7/site-packages/neutron/agent/linux/ip_lib.py", line 335, in _sysctl
ERROR neutron.agent.linux.ip_lib check_exit_code=True)
ERROR neutron.agent.linux.ip_lib File "/usr/lib/python2.7/site-packages/neutron/agent/linux/ip_lib.py", line 927, in execute
ERROR neutron.agent.linux.ip_lib log_fail_as_error=log_fail_as_error, **kwargs)
ERROR neutron.agent.linux.ip_lib File "/usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py", line 140, in execute
ERROR neutron.agent.linux.ip_lib raise RuntimeError(msg)
ERROR neutron.agent.linux.ip_lib RuntimeError: Exit code: 255; Stdin: ; Stdout: ; Stderr: sysctl: cannot stat /proc/sys/net/ipv6/conf/brqc766b4dc-d2/disable_ipv6: No such file or directory

Indeed:
# ls /proc/sys/net/ipv6/
ls: cannot access /proc/sys/net/ipv6/: No such file or directory

This is because the system was started with the ipv6.disable=1 Linux kernel boot option.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/363634

[OpenStack Infra (hudson-openstack)]

Change abandoned by Armando Migliaccio (<email address hidden>) on branch: master
Review: https://review.openstack.org/363634
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/363634
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=bfe947b26266e13251b7ba972d8b57e67e9ebb02
Submitter: Zuul
Branch: master

commit bfe947b26266e13251b7ba972d8b57e67e9ebb02
Author: Adrien Cunin <email address hidden>
Date: Sun Sep 4 21:44:18 2016 +0200

    Skip IPv6 sysctl calls when IPv6 is disabled

    If IPv6 is globally disabled, do not try to run any IPv6
    sysctls as they will all fail as the parameters do not exist.

    Change-Id: I789dbbe1c44581978c51f8c3c1d22aef10cbe01a
    Closes-Bug: #1618878

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 12.0.0.0b2 development milestone.