Unable to start placement wsgi app without conf file

[Chris Dent]

oslo_config allows configuration to come from the process environment (e.g., OS_PLACEMENT_DATABASE__CONNECTION). This was developed to allow services that use oslo_config to hosted within immutable containers.

However, as currently written, the placement-wsgi app (in both nova and placement) cannot start if there isn't at least an empty placement.conf, either in /etc/placement or in the directory defined by OS_PLACEMENT_CONFIG_DIR.

It's easy enough to work around this: set the empty file in the container and forget about it.

In placement/wsgi.py:

    conf.CONF(argv[1:], project='placement',
              version=version_info.version_string(),
              default_config_files=default_config_files)

is the call that causes the problem, because default_config_files is always non-None, even when the original default is being used. We can fix this by only setting the value when a non default is being used.

(This is possible now that placement is placement, not nova).

[Chris Dent (cdent)]

in progress with https://review.openstack.org/#/c/619049/

not sure why things aren't being automatic