inventory overrides causing dynamic_inventory.py to stacktrace

[Kevin Carter]

When overriding the property "is_metal" within the user defined env.d files I've found that the inventory generator raises an error indicating it's encountered a "KeyError" when adding addresses to a given container.

``` traceback
Traceback (most recent call last):
  File "./inventory/dynamic_inventory.py", line 78, in <module>
    output = generate.main(**all_args)
  File "/opt/openstack-ansible/playbooks/inventory/../../lib/generate.py", line 1100, in main
    user_defined_config
  File "/opt/openstack-ansible/playbooks/inventory/../../lib/generate.py", line 730, in container_skel_load
    static_routes=p_net.get('static_routes')
  File "/opt/openstack-ansible/playbooks/inventory/../../lib/generate.py", line 572, in _add_additional_networks
    static_routes
  File "/opt/openstack-ansible/playbooks/inventory/../../lib/generate.py", line 572, in _add_additional_networks
    static_routes
  File "/opt/openstack-ansible/playbooks/inventory/../../lib/generate.py", line 638, in _add_additional_networks
    phg = user_config[cphg][container_host]
KeyError: u'aio1_nova_scheduler_container-e973eb06'
```

This is an example env.d file defined as nova.yml within the /etc/openstack_deploy/env.d directory

``` yaml
container_skel:
  nova_api_metadata_container:
    properties:
      is_metal: true

  nova_api_os_compute_container:
    properties:
      is_metal: true

  nova_api_placement_container:
    properties:
      is_metal: true

  nova_compute_container:
    properties:
      is_metal: true

  nova_conductor_container:
    properties:
      is_metal: true

  nova_scheduler_container:
    properties:
      is_metal: true

  nova_console_container:
    properties:
      is_metal: true
```

The debug log for the inventory generation process can be found here: http://cdn.pasteraw.com/ct5gwf0vv7nlpkppwvrwv6rwoc8kwuf

----

The desired outcome would be to have the inventory generator allow me to flip the bit on the "is_metal" property leaving the existing containers untouched. This would allow a deployer to change the deployment strategy within a given release without having to first destroy the existing containers and remove their entries from inventory.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/531123
Committed: https://git.openstack.org/cgit/openstack/openstack-ansible/commit/?id=81e1f8d173d663e5f7f6a385e89359c3e9d75a54
Submitter: Zuul
Branch: master

commit 81e1f8d173d663e5f7f6a385e89359c3e9d75a54
Author: Jean-Philippe Evrard <email address hidden>
Date: Thu Jan 4 10:43:26 2018 +0000

    Include P-Q changes into the upgrade script

    We need to include changes in the upgrade script to handle
    the changes done during the Queens timeframe:

    - Inventory is fixed to prevent a stacktrace if a container
      default was moved from is_metal: False to is_metal: True,
      and now respects existing container properties.
    - Ensuring previous inventory location isn't overriding the
      Queens inventory location in memory, by unsetting
      ANSIBLE_INVENTORY.
    - Ensuring all containers are using the repo that was build
      during the upgrade.

    Change-Id: I0fd3a8803bf345ccad07dc97968e104cd0a7bf70
    Partial-Bug: #1741462
    Closes-Bug: #1675810

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/openstack-ansible 17.0.0.0b3 development milestone.