Open Stack

Hi Mike, comments are inline.

On Thu, Mar 10, 2016 at 10:30 AM, Mike Scherbakov <mscherbakov at mirantis.com>
wrote:

> Hi folks,
> in order to make a decision whether we need to support example plugins,
> and if actually need them [1], I'd suggest to discuss more common things
> about plugins.
>
> My thoughts:
> 1) This is not good, that our plugins created for Fuel 8 won't even
> install on Fuel 9. By default, we should assume that plugin will work at
> newer version of Fuel. However, for proper user experience, I suggest to
> create meta-field "validated_against", where plugin dev would provide
> versions of Fuel this plugin has been tested with. Let's say, it was tested
> against 7.0, 8.0. If user installs plugin in Fuel 9, I'd suggest to show a
> warning saying about risks and the fact that the plugin has not been tested
> against 9. We should not restrict intsallation against 9, though.
>

User can install all previous version of plugins on Fuel 9, but those
plugins are not going to be shown for Mitaka-9.0 release (for old release
only). It should be added into compatibility list in order to make it
compatible with OpenStack release. If you want to allow to enable plugin
for specific release, it's going to be tricky since the format of DSL for
different releases can be different, and you may get not only broken
deployment, but 500 error from Nailgun since it will get unexpected format
of data.


>
> 2) We need to keep backward compatibility of pluggable interface for a few
> releases. So that plugin developer can use pluggable interface of version
> x, which was supported in Fuel 6.1. If we still support it, it would mean
> (see next point) compatibility of this plugin with 6.1, 7.0, 8.0, 9.0. If
> we want to deprecate pluggable interface version, we should announce it,
> and basically follow standard process of deprecation.
>

It requires clarification, in fact we support backward compatibility for
previous release, this requirement is a result of Fuel upgradability
requirement (after upgrade to new Fuel plugins won't get broken for old
releases).
If we are talking about plugin format improvement/changes, then yes, we are
thinking about deprecation, but it should be improved by sending
announcement/writing document/providing appropriate messages during build.


> 3) Plugin's ability to work against multiple releases of Fuel
> (multi-release support). If if..else clauses to support multiple releases
> are fairly minimal, let's say take less that 10% of LOC, I'd suggest to
> have this supported. Just because it will be easier for plugin devs to
> support their plugin code (no code duplication, single repo for multiple
> releases).
>
> If you are referring to compatibility with master node, it's being
supported.
If it's about multi-release (OpenStack) support, it will take more time
(and problems afterwards) to drop support of multi-release plugins. Hope
that our tech debt will be fixed in the next release, since FFE was not
granted for the current release [1]. Also we've had a huge discussion about
it in a separate thread [2].

[1] https://review.openstack.org/#/c/271417/
[2]
http://lists.openstack.org/pipermail/openstack-dev/2016-February/086381.html

Thoughts?
>
> [1]
> http://lists.openstack.org/pipermail/openstack-dev/2016-March/088211.html
> --
> Mike Scherbakov
> #mihgen
>
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