KeyError: 'default_dns_nameservers' in Horizon

It looks like this was caused by https://review.opendev.org/#/c/655208/, which changes the handling of defaults for config in horizon. Since we override the OPENSTACK_NEUTRON_NETWORK variable in local_settings.py, but do not include the default for 'default_dns_nameservers'. A simple workaround for kolla-ansible is to include the default empty list value in our override.

I think this is a bug in horizon though - they should still tolerate missing defaults in dict format config variables.

I'd expect this to apply also to segmentation_id_range and other fields.

This is a bug in horizon. Dict-type settings should use .get() method with the default values from defaults.py (rather than hard-coded default values). I would like to take care of this just after milestone-3 (this Thursday).

Note that this is not limited to OPENSTACK_NEUTRON_NETWORK. This affects all dict-type settings.

Thanks for picking this up amotoki.

Related fix proposed to branch: master
Review: https://review.opendev.org/684792

Fix proposed to branch: master
Review: https://review.opendev.org/684793

Fix proposed to branch: master
Review: https://review.opendev.org/684794

Fix proposed to branch: master
Review: https://review.opendev.org/684795

Fix proposed to branch: master
Review: https://review.opendev.org/684796

Fix proposed to branch: master
Review: https://review.opendev.org/684797

Fix proposed to branch: master
Review: https://review.opendev.org/684798

Change abandoned by Akihiro Motoki (<email address hidden>) on branch: master
Review: https://review.opendev.org/684798
Reason: Squashed into https://review.opendev.org/#/c/684792/2 to simplify the patch.

Change abandoned by Akihiro Motoki (<email address hidden>) on branch: master
Review: https://review.opendev.org/684797
Reason: Squashed into https://review.opendev.org/#/c/684792/2 to simplify the patch.

Change abandoned by Akihiro Motoki (<email address hidden>) on branch: master
Review: https://review.opendev.org/684796
Reason: Squashed into https://review.opendev.org/#/c/684792/2 to simplify the patch.

Change abandoned by Akihiro Motoki (<email address hidden>) on branch: master
Review: https://review.opendev.org/684795
Reason: Squashed into https://review.opendev.org/#/c/684792/2 to simplify the patch.

Change abandoned by Akihiro Motoki (<email address hidden>) on branch: master
Review: https://review.opendev.org/684794
Reason: Squashed into https://review.opendev.org/#/c/684792/2 to simplify the patch.

Change abandoned by Akihiro Motoki (<email address hidden>) on branch: master
Review: https://review.opendev.org/684793
Reason: Squashed into https://review.opendev.org/#/c/684792/2 to simplify the patch.

Reviewed: https://review.opendev.org/684792
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=ec970fd6e85b19126409ef39aefa013bac701503
Submitter: Zuul
Branch: master

commit ec970fd6e85b19126409ef39aefa013bac701503
Author: Akihiro Motoki <email address hidden>
Date: Wed Sep 25 21:29:05 2019 +0900

    Handle partial dict setting

    In Train cycle, we moved the definition of default values
    to openstack_dashboard/defaults.py. The current code accesses
    a dict member using []. It requires operators to define a dict
    setting with a full member.

    This commit allows to use dict-type settings with partial members.

    A new function is introduced to retrieve a dict-type setting
    considering default values defined in
    {openstack_dashboard,horizon,openstack_auth}/defaults.py

    Change-Id: I7ff0ad4bca698aef9c0eba370b0570200a14367a
    Closes-Bug: #1843104

Thanks for fixing this.

This issue was fixed in the openstack/horizon 16.0.0.0rc1 release candidate.