nova-api does not support config dirs when run under apache via mod_wsgi

[sean mooney]

currently nova assume that when the nova-api si run under a wsgi server that server supports
passing command line arguments to the wsgi script.

that is not the case with mod_wsgi

as a result we do not support using a config director when running under mod_wsgi or passing any other arguments.

as a result when we run nova-api under mod_wsgi we fallback to a hardcoded set of config file names

https://github.com/openstack/nova/blob/b1958b7cfa6b8aca5b76b3f133627bb733d29f00/nova/api/openstack/wsgi_app.py#L34-L46

CONFIG_FILES = ['api-paste.ini', 'nova.conf']

LOG = logging.getLogger(__name__)

objects.register_all()

def _get_config_files(env=None):
    if env is None:
        env = os.environ
    dirname = env.get('OS_NOVA_CONFIG_DIR', '/etc/nova').strip()
    return [os.path.join(dirname, config_file)
            for config_file in CONFIG_FILES]

This prevents operators form using the /etc/nova/nova.config.d/
to provide a directory containing multiple config files

This can be addressed in several ways.

first we can provide a env varabel for additional command line args to be parsed
these can be parsed here as we do for uwsgi or the python wsgi server
https://github.com/openstack/nova/blob/b1958b7cfa6b8aca5b76b3f133627bb733d29f00/nova/api/openstack/wsgi_app.py#L96-L98

second we could replace or augment our custom _get_config_files with a call to the genirc implementation provide in oslo.config

https://github.com/openstack/oslo.config/blob/68cefad313bd03522e99b3de95f1786ebea45d4b/oslo_config/cfg.py#L281-L339

thrid we can provide a way to extend
CONFIG_FILES = ['api-paste.ini', 'nova.conf']
via a new env var.
e.g. OS_NOVA_EXTRA_CONFIGS="nova.config.d/01-nova.conf,nova.config.d/02-nova-secret.conf,"

we can do all three or any one of them to enable the usecase of supporting config directories although only the first option allows other command line args to be passed.

[sean mooney (sean-k-mooney)]

after reviewing some of the main openstack porjects (keystone, glance cinder placment)

only keystone currenlty porvides a way to configure the config files when running under mod_wsgi

there solution is to expose an envionment variabel to allow the opeartor to list the files to load.

https://github.com/openstack/keystone/blob/7d4047cb69139c22f4e321e9ba8b287a47168df2/keystone/server/flask/core.py#L74-L88

to keep concitnecy i will adopt the same appch defaulting the configs to the current set but adding a OS_NOVA_CONFIG_FILES atribute. i will also use ";" as the seperator insted of comma for consitency.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/nova/+/864014

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/nova/+/864014
Committed: https://opendev.org/openstack/nova/commit/73fe84fa0ea6f7c7fa55544f6bce5326d87743a6
Submitter: "Zuul (22348)"
Branch: master

commit 73fe84fa0ea6f7c7fa55544f6bce5326d87743a6
Author: Sean Mooney <email address hidden>
Date: Tue Nov 8 15:00:22 2022 +0000

    Support multiple config file with mod_wsgi

    Unlike uwsgi, apache mod_wsgi does not support passing
    commandline arguments to the python wsgi script it invokes.

    As a result while you can pass --config-file when hosting the
    api and metadata wsgi applications with uwsgi there is no
    way to use multiple config files with mod_wsgi.

    This change mirrors how this is supported in keystone today
    by intoducing a new OS_NOVA_CONFIG_FILES env var to allow
    operators to optional pass a ';' delimited list of config
    files to load.

    This change also add docs for this env var and the existing
    undocumented OS_NOVA_CONFIG_DIR.

    Closes-Bug: 1994056
    Change-Id: I8e3ccd75cbb7f2e132b403cb38022787c2c0a37b

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/zed
Review: https://review.opendev.org/c/openstack/nova/+/867162

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/nova/+/867162
Committed: https://opendev.org/openstack/nova/commit/d92d0934188a14741dd86949ddf98bd1208f3d96
Submitter: "Zuul (22348)"
Branch: stable/zed

commit d92d0934188a14741dd86949ddf98bd1208f3d96
Author: Sean Mooney <email address hidden>
Date: Tue Nov 8 15:00:22 2022 +0000

    Support multiple config file with mod_wsgi

    Unlike uwsgi, apache mod_wsgi does not support passing
    commandline arguments to the python wsgi script it invokes.

    As a result while you can pass --config-file when hosting the
    api and metadata wsgi applications with uwsgi there is no
    way to use multiple config files with mod_wsgi.

    This change mirrors how this is supported in keystone today
    by intoducing a new OS_NOVA_CONFIG_FILES env var to allow
    operators to optional pass a ';' delimited list of config
    files to load.

    This change also add docs for this env var and the existing
    undocumented OS_NOVA_CONFIG_DIR.

    Closes-Bug: 1994056
    Change-Id: I8e3ccd75cbb7f2e132b403cb38022787c2c0a37b
    (cherry picked from commit 73fe84fa0ea6f7c7fa55544f6bce5326d87743a6)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/placement/+/869863

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 26.1.0 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 27.0.0.0rc1 release candidate.

[OpenStack Infra (hudson-openstack)]

Change abandoned by "sean mooney <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/placement/+/869863
Reason: i discoverd later that htis is not needed.

while you cant pass an array of or set of config files to placement

placement will look in /etc/placement/placement.conf.d/ for all .conf files and load them using so this is not need

multiple config files can be placed in /etc/placement/placement.conf.d/ or any other direcotry search by oslo.config find_config_dirs

https://github.com/openstack/oslo.config/blob/68cefad313bd03522e99b3de95f1786ebea45d4b/oslo_config/cfg.py#L312-L339

"""
We default to two config dirs: [${project}.conf.d/, ${prog}.conf.d/].
    If no project name is supplied, we only look for ${prog.conf.d/}.

    And we look for those config dirs in the following directories::

      ~/.${project}/
      ~/
      /etc/${project}/
      /etc/
      ${SNAP_COMMON}/etc/${project}
      ${SNAP}/etc/${project}
"""