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<blockquote cite="mid:20160812133747.GB25616@gmx.com" type="cite">
<pre wrap="">
I was leaning towards a separate repo until I started thinking about all
the overhead and complications this would cause. It's another repo for
cores to watch. It would cause everyone extra complication in setting up
their CI, which is already one of the biggest roadblocks. It would make
it a little harder to do things like <a class="moz-txt-link-freetext" href="https://review.openstack.org/297140">https://review.openstack.org/297140</a>
and <a class="moz-txt-link-freetext" href="https://review.openstack.org/346470">https://review.openstack.org/346470</a> to be able to generate this:
<a class="moz-txt-link-freetext" href="http://docs.openstack.org/developer/cinder/drivers.html">http://docs.openstack.org/developer/cinder/drivers.html</a>. Plus more infra
setup, more moving parts to break, and just generally more
complications.
All things that can be solved for sure. I just question whether it would
be worth having that overhead. Frankly, there are better things I'd like
to spend my time on.
I think at this point my first preference would actually be to define a
new tag. This addresses both the driver removal issue as well as the
backporting of driver bug fixes. I would like to see third party drivers
recognized and treated as being different, because in reality they are
very different than the rest of the code. Having something like
follows_deprecation_but_has_third_party_drivers_that_dont would make a
clear statement that their is a vendor component to this project that
really has to be treated differently and has different concerns
deployers need to be aware of.
Barring that, I think my next choice would be to remove the tag. That
would really be unfortunate as we do want to make it clear to users that
Cinder will not arbitrarily break APIs or do anything between releases
without warning when it comes to non-third party drivers. But if that is
what we need to do to effectively communicate what to expect from
Cinder, then I'm OK with that.
My last choice (of the ones I'm favorable towards) would be marking a
driver as untested/unstable/abandoned/etc rather than removing it. We
could flag these a certain way and have then spam the logs like crazy
after upgrade to make it very and painfully clear that they are not
being maintained. But as Duncan pointed out, this doesn't have as much
impact for getting vendor attention. It's amazing the level of executive
involvement that can happen after a patch is put up for driver removal
due to non-compliance.
Sean
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</pre>
</blockquote>
I believe there is a compromise that we could implement in Cinder
that enables us to have a deprecation<br>
of unsupported drivers that aren't meeting the Cinder driver
requirements and allow upgrades to work<br>
without outright immediately removing a driver.<br>
<br>
<ol>
<li>Add a 'supported = True' attribute to every driver.</li>
<li>When a driver no longer meets Cinder community requirements,
put a patch up against the driver</li>
<li>When c-vol service starts, check the supported flag. If the
flag is False, then log an exception, and disable the driver.</li>
<li>Allow the admin to put an entry in cinder.conf for the driver
in question "enable_unsupported_driver = True". This will allow
the c-vol service to start the driver and allow it to work. Log
a warning on every driver call. <br>
</li>
<li>This is a positive acknowledgement by the operator that they
are enabling a potentially broken driver. Use at your own risk.<br>
</li>
<li>If the vendor doesn't get the CI working in the next release,
then remove the driver. <br>
</li>
<li>If the vendor gets the CI working again, then set the
supported flag back to True and all is good. <br>
</li>
</ol>
<p><br>
This allows a deprecation period for a driver, and keeps operators
who upgrade their deployment from losing access to their volumes
they have on those back-ends. It will give them time to contact
the community and/or do some research, and find out what happened
to the driver. This also potentially gives the operator time to
find a new supported backend and start migrating volumes. I say
potentially, because the driver may be broken, or it may work
enough to migrate volumes off of it to a new backend.<br>
</p>
<p>Having unsupported drivers in tree is terrible for the Cinder
community, and in the long run terrible for operators.<br>
Instantly removing drivers because CI is unstable is terrible for
operators in the short term, because as soon as they upgrade
OpenStack, they lose all access to managing their existing
volumes. Just because we leave a driver in tree in this state,
doesn't mean that the operator will be able to migrate if the
drive is broken, but they'll have a chance depending on the state
of the driver in question. It could be horribly broken, but the
breakage might be something fixable by someone that just knows
Python. If the driver is gone from tree entirely, then that's a
lot more to overcome.<br>
</p>
<p>I don't think there is a way to make everyone happy all the time,
but I think this buys operators a small window of opportunity to
still manage their existing volumes before the driver is removed.
It also still allows the Cinder community to deal with unsupported
drivers in a way that will motivate vendors to keep their stuff
working.<br>
</p>
<p>My $0.02<br>
Walt<br>
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