[Openstack] Openstack Nova/Quantum :; api-paste.ini file

Trinath Somanchi trinath.somanchi at gmail.com
Fri Dec 7 07:17:43 UTC 2012

Hi Kevin-

Thanks for the reply and making me understand the data flow.

I have one more doubt in plate.

I see that in api-paste.ini, with respect to the online available

I see that the auth_host, auth_port, admin_tenant_name, admin_user,
admin_password etc... are all hard coded.

But then, suppose that we have "N" number of compute nodes.where we have
agents running which might need these variables for all the variables,
these options must be manually hardcoded.

Also we set these variables as environmental variables.

How can we refer the Environmental variables for the variables in the
configuration files?

Can you guide me understand the issue.

Thanks in advance


On Fri, Dec 7, 2012 at 2:09 AM, Kevin L. Mitchell <
kevin.mitchell at rackspace.com> wrote:

> On Thu, 2012-12-06 at 23:58 +0530, Trinath Somanchi wrote:
> > Suppose, we have a resquest to Nova..
> >
> > The following steps are performed...
> >
> > 1. The request is captured by webob and is authenticated by keystone
> > and is decorated to wsgi app
> Not quite correct; webob decorates (some of) the functions called, so
> all functions in the WSGI stack end up having the WSGI calling
> convention ("func(env, start_response)").  The bulk of the middleware
> uses the webob wsgify decorator, but there are some exceptions
> (auth_token being one of them).  Other than that point, this is correct.
> > 2. Nova-api maps the url params to extensions
> nova-api maps the URIs to controller classes and methods on those
> classes (it uses the routes package to accomplish this).  Some of those
> classes are extensions, rather than core; some of those interfaces are
> further extended by the extensions (the extensions infrastructure can
> accomplish both).  IOW, you are essentially correct…
> > 3. Nova-api extensions return the data dict.. Which webob returns as
> > response to the request in json/xml format...
> Well, it's nova that serializes the data dict to the appropriate format;
> webob just handles the mechanics of sending the serialized data back,
> along with appropriate HTTP headers.  The serialization framework is a
> little complicated, so let's omit it for now…
> > 4. Paste-api helps the keystone and other modules for update of the
> > request...
> PasteDeploy builds the processing pipeline based on the values in
> api-paste.ini and friends, putting the middleware into the correct
> order, with the final application at the end of the chain.  (Note that
> middleware is *not* extension, but rather additional processing done on
> the request as a whole.)
> > Kindly please help me by validating my understanding ...
> I think you've fairly well understood most of it, aside from some
> subtleties that I've tried to correct above.
> --
> Kevin L. Mitchell <kevin.mitchell at rackspace.com>
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Trinath Somanchi,
+91 9866 235 130
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