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On Wed, Mar 25, 2015 at 3:58 PM, Sean Dague <sean at dague.net> wrote:

> On 03/25/2015 03:16 AM, Deepak Shetty wrote:
> >
> >
> > On Wed, Mar 25, 2015 at 11:29 AM, Deepak Shetty <dpkshetty at gmail.com
> > <mailto:dpkshetty at gmail.com>> wrote:
> >
> >
> >
> >     On Wed, Mar 25, 2015 at 12:58 AM, Ian Wienand <iwienand at redhat.com
> >     <mailto:iwienand at redhat.com>> wrote:
> >
> >         On 03/24/2015 03:17 PM, Deepak Shetty wrote:
> >         > For eg: Look at [1]
> >         > [1]
> https://github.com/stackforge/devstack-plugin-glusterfs/blob/master/devstack/settings
> >
> >         > I would like ability to change these while I use the
> enable_plugin
> >         > apporach to setup devstack w/ GlusterFS per my local glusterfs
> setup
> >
> >         So I think the plugin should do
> >
> >
>  CINDER_ENABLED_BACKENDS=${CINDER_ENABLED_BACKENDS:-glusterfs:glusterfs,lvm:lvm1}
> >
> >         i.e. provide a default only if the variable is unset.
> >
> >
> >     Bah! That was easy, i should have figured that myself :)
> >     Thanks for catching that
> >
> >
> >
> >         This seems like one of those "traps for new players" and is one
> >         concern I have with devstack plugins -- that authors keep having
> to
> >         find out lessons learned independently.  I have added a note on
> this
> >         to the documentation in [1].
> >
> >         -i
> >
> >         [1] https://review.openstack.org/#/c/167375/
> >
> >
> >     Great, i +1'ed it.
> >
> >     Also i posted patch to fix settings file @
> >     https://review.openstack.org/167494
> >
> >
> > Ian,
> >    Looks like usign bash default in settings file of plugin is not
> > working, in my patch it didn't use glusterfs driver, it used LVM
> (default)
> > I think whats happening here is that by the time settings file is
> > sourced, CINDER_ENABLED_BACKENDS is already set to lvm by lib/cinder
> > so settings file's default value is never taken
> >
> > IIUC there are 3 scenarios (taking CINDER_ENABLED_BACKENDS as example
> var) :
> >
> > 1) localrc doesn't have CINDER_ENABLED_BACKENDS and enable_plugin
> >     - Here we want the lib/cinder's default value to be taken
> >     - this should work fine
> >
> > 2) localrc doesn't have CINDER_ENABLED_BACKENDS but has enable_plugin
> > glusterfs
> >     - Here we want the plugin's default values to be taken, but its not
> > as lib/cinder already initialized CINDER_ENABLED_BACKENDS to use lvm
> backend
> >     - Thus broken
> >
> > 3) localrc has both CINDER_ENABLED_BACKENDS and enable_plugin glusterfs
> > specified
> >     - Here we want CINDER_ENABLED_BACKENDS present in my localrc to be
> > chosen
> >     - This will work as by the time settings file is sourced
> > CINDER_ENABLED_BACKENDS is already initialised to my value in localrc
> >
> > So #2 scenario would need some changes in stack.sh handling of plugin
> code ?
>
> Right, so this code runs late enough that you don't get to change the
> defaults. I think that's ok.
>

Had a question here, why is this source in the end ?

plugin config is something that should be allowed to be overridden, thus
this should
be sourced in the beginning and then anything in localrc will override what
the plugin
sets/unsets

That ways if someone wants to use plugin config, just enable the plugin.
if they want to override, enable plugin and override the env specific parts

Am i thinkign wrong ?

thanx,
deepak
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