Open Stack

(This is a followup to
http://lists.openstack.org/pipermail/openstack-dev/2017-May/116267.html
but I don't have that around anymore to make a proper response to.)

In a devstack change:

     https://review.openstack.org/#/c/457715/

nova-api and nova-metadata will be changed to run as WSGI
applications with a uwsgi server by default. This helps to enable
a few recent goals:

* everything under systemd in devstack
* minimizing custom ports for HTTP in devstack
* is part of a series of changes[1] which gets the compute api working
   under WSGI, including some devref for wsgi use:
   https://docs.openstack.org/developer/nova/wsgi.html
* helps enforce the idea that any WSGI server is okay

This last point is important consideration for deployers: Although
devstack will (once the change merges) default to using a
combination of apache2, mod_proxy_uwsgi, and uwsgi there is zero
requirement that deployments replicate that arrangement. The new
'nova-api-wsgi' and 'nova-metadata-wsgi' script provide a
module-level 'application' that can be run by any WSGI compliant
server.

In those contexts things like the path-prefix of an application and
the port used (if any) to host the application are entirely in the
domain of the web server's config, not the application. This is
a good thing, but it does mean that any deployment automation needs
to make some decisions about how to manipulate the web server's
configuration.

Some other details which might be relevant:

In the devstack change the compute service is registered to run on a
default port of either 80 or 443 at '/compute' and _not_ on a custom
port.

The metadata API, however, continues to run as its own service on
its own port. In fact, it runs using solely uwsgi, without apache2
being involved at all.

Please follow up if there any questions.


[1] https://review.openstack.org/#/c/457283/
     https://review.openstack.org/#/c/459413/
     https://review.openstack.org/#/c/461289/

-- 
Chris Dent                  ┬──┬◡ﾉ(° -°ﾉ)       https://anticdent.org/
freenode: cdent                                         tw: @anticdent