Add env.d directory for extra containers

[David Wilde]

We need a way to add additional containers to the infrastructure without modifying the provided openstack_environment.yml file. This should be similar to the way we handle extra configurations in etc/openstack_deploy/conf.d

[Kevin Carter (kevin-carter)]

+1 for future extensibility this should be added in.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/170558
Committed: https://git.openstack.org/cgit/stackforge/os-ansible-deployment/commit/?id=27f1d2d3ec72358c442483ab124db9f43bfa94ee
Submitter: Jenkins
Branch: master

commit 27f1d2d3ec72358c442483ab124db9f43bfa94ee
Author: Dave Wilde <email address hidden>
Date: Fri Apr 3 10:52:32 2015 -0500

    Add env.d extra configuration directory to etc/openstack_deploy/

    Like etc/openstack_deploy/conf.d/ we need a way to add additional
    containers to the infrastructure without modifying the provided
    openstack_environment.yml file. This patch looks for an env.d
    directory and merges their configurations into the inventory. An
    example extra_container configuration file is also provided.

    Closes-bug: 1440117

    Change-Id: Ibc83770e69efb67996a012c96766b4a88774986e