[RFE] Undercloud - allow enabling routed_networks on undercloud upgrade

[Harald Jensås]

Description of problem:
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When deploying the undercloud support for routed networks must be enabled using the ``enable_routed_networks`` option in ``undercloud.conf``. If the option is set to False (the default) it is not possible to change it to True and re-run undercloud installer to enable support for routed networks.

Prior to Rocky it had to be like this because neutron did not support migrating a non-routed network to a routed network. Since we now have support to change a network from being non-routed to routed in neutron, we should enable this in the undercloud so that an existing deployment can be scaled by adding nodes on different network segments.

Additional info:
----------------

Once routed networks is enabled, it cannot be disabled.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/601369

[OpenStack Infra (hudson-openstack)]

Change abandoned by Juan Antonio Osorio Robles (<email address hidden>) on branch: master
Review: https://review.openstack.org/601369
Reason: clearing the gate

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/601369
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=3892154d5a4f38e21be0cd4b490205900f5b8e1c
Submitter: Zuul
Branch: master

commit 3892154d5a4f38e21be0cd4b490205900f5b8e1c
Author: Harald Jensås <email address hidden>
Date: Wed Sep 5 15:18:21 2018 +0200

    Allow enabling routed networks on undercloud update|upgrade

    Since Rocky neutron has support to enable routed networks on
    existing an network and subnet if certain conditions are met.
    The tripleo undercloud does meet these conditions.

    This change updates the extraconfig post script that creates
    the neutron ctlplane networks. Any non routed network is
    updated to a routed network if 'enable_routed_networks' = True
    in the configuration.

    Closes-Bug: #1790877
    Change-Id: Idf2dd4c158d29b147d48153d3626cf403059d660

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/tripleo-heat-templates 10.2.0 release.