remove paste configuration from the config files

[Dan Prince]

Paste config files are cool and allow middleware adjustments, etc but really are more of an internal implementation detail than a config file.

Lets consider separating the paste configs into separate files.

[Jay Pipes (jaypipes)]

I'd be in favour of this. Would make upgrading the paste.deploy parts of the config setup easier in packaging, leading to less bugs like: https://bugs.launchpad.net/glance/+bug/814981

[Eoghan Glynn (eglynn)]

Here's a proposal for addressing this issue and also making it less likely that users will ever need to edit paste deploy config directly:

1. Strip out the paste deploy config from the main etc/glance-*.conf file into corresponding /usr/share/glance-*-paste.conf files

2. For each major middleware deployment option (minimal, with keystone, with caching, with keystone and caching etc.) define a seperate pipeline section, e.g.:

# minimal pipeline
[pipeline:glance-api-generic]
pipeline = versionnegotiation context apiv1app

# pipeline with keystone enabled
[pipeline:glance-api-keystone]
pipeline = versionnegotiation authtoken auth-context apiv1app

# pipeline with caching enabled
[pipeline:glance-api-caching]
pipeline = versionnegotiation context cache apiv1app

# ... etc.

3. Add a new config option, allowing the active pipeline to be selected in the primary config, e.g:

# etc/glance-api.conf
deployment_flavor = keystone

The idea being that most users need not be concerned that keystone support is in fact realized by traversing two separate filters, authtoken and auth-context. The default would be the most minimal/generic pipeline.

4. Before calling into wsgi.paste_deploy_app(), concatenate "-%(deployment_flavor)s" to the app_name so that correct pipeline is selected.

Thoughts?

If there are no objections to the above, I'll go ahead and put together a patch implementing the change.

[Jay Pipes (jaypipes)]

Hi Eoghan!

So, I think that your proposal has some merit. However, I think that there are two things that need to be addressed (perhaps as separate bugs):

1) (this bug) Separating paste-deploy stuff from the regular configuration option files
2) Making it easier for newbies to understand the different ways to set up filters and middleware

I think fixing #1 would be a good first step. For the second, I could see using your solution here (using configuration option to driver the picking of a deployment pipeline), or instead having multiple well-commented paste.ini files in /etc that showed examples of configuring the pipelines for different needs.

For instance, etc/paste/ could contain:

etc/paste/glance-api-minimal-paste.ini
etc/paste/glance-api-auth-no-cache-paste.ini
etc/paste/glance-api-auth-cache-paste.ini

Each showing examples of how to configure the filter and middleware pipelines?

-jay

[Eoghan Glynn (eglynn)]

Thanks for the feedback, Jay.

In terms of the approach to achieving objective #2, a key question would whether there's anything else in the *-paste.ini (other than the pipeline) that users may want to change.

If so, then your suggestion of providing well-commented stock paste.ini files would probably make more sense.

If on the other hand, the pipeline is the only aspect of the paste config likely to be modified by users, then perhaps completely encapsulating the paste config would give glance users a slightly gentler on-ramp?

[Jay Pipes (jaypipes)]

I don't think that there would be anything other than pipeline configuration in the *paste.ini files, no... but of course, we do want to give users the ability to configure their own custom middleware and whatnot, so if we did go the "configure with flags" route, we'd still want to keep the ability to override everything for advanced users.

[Eoghan Glynn (eglynn)]

Submitted patch series for review:

https://review.openstack.org/3036
https://review.openstack.org/3037
https://review.openstack.org/3038

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/3036
Committed: http://github.com/openstack/glance/commit/14593a3b9691bdb6920c7fefe98d1f817495abb9
Submitter: Jenkins
Branch: master

commit 14593a3b9691bdb6920c7fefe98d1f817495abb9
Author: Eoghan Glynn <email address hidden>
Date: Fri Jan 13 00:31:00 2012 +0000

    Split out paste deployment config from the core glance
    *.conf files into corresponding *-paste.ini files.

    Fixes LP #815208

    Change-Id: I5acb8488cc25bb3c7dd735c8c2b0fe62fcea8e5e