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<font size="-1">I've been working with Nova's versioned objects
lately to help catch people when object changes are made. There is
a lot of object-related tests in Nova for this, and a major one I
can see helping this situation is this test [1]. Looking through
the different versioned objects within Magnum, I don't see any
objects that hold subobjects, so tests like [2] are not really
necessary yet.<br>
<br>
I have uploaded a review for bringing [1] from Nova into Magnum
[3]. I think this will be a major step in the right direction
towards keeping track of object changes that will help with
rolling upgrades.<br>
<br>
[1]:
<a class="moz-txt-link-freetext" href="https://github.com/openstack/nova/blob/master/nova/tests/unit/objects/test_objects.py#L1262-L1286">https://github.com/openstack/nova/blob/master/nova/tests/unit/objects/test_objects.py#L1262-L1286</a><br>
[2]:
<a class="moz-txt-link-freetext" href="https://github.com/openstack/nova/blob/master/nova/tests/unit/objects/test_objects.py#L1314">https://github.com/openstack/nova/blob/master/nova/tests/unit/objects/test_objects.py#L1314</a><br>
[3]: <a class="moz-txt-link-freetext" href="https://review.openstack.org/#/c/217342/">https://review.openstack.org/#/c/217342/</a><br>
</font><br>
<div class="moz-cite-prefix">On 8/26/2015 3:47 AM, Grasza, Grzegorz
wrote:<br>
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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I noticed that right now, when we make
changes (adding/removing fields) in
<a moz-do-not-send="true"
href="https://github.com/openstack/magnum/tree/master/magnum/objects">https://github.com/openstack/magnum/tree/master/magnum/objects</a>
, we don't change object versions.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The idea of objects is that each change in
their fields should be versioned, documentation about the
change should also be written in a comment inside the object
and the obj_make_compatible method should be implemented or
updated. See an example here:<o:p></o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="https://github.com/openstack/nova/commit/ad6051bb5c2b62a0de6708cd2d7ac1e3cfd8f1d3#diff-7c6fefb09f0e1b446141d4c8f1ac5458L27">https://github.com/openstack/nova/commit/ad6051bb5c2b62a0de6708cd2d7ac1e3cfd8f1d3#diff-7c6fefb09f0e1b446141d4c8f1ac5458L27</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The question is, do you think magnum should
support rolling upgrades from next release or maybe it's still
too early?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">If yes, I think core reviewers should start
checking for these incompatible changes.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">To clarify, rolling upgrades means support
for running magnum services at different versions at the same
time.<o:p></o:p></p>
<p class="MsoNormal">In Nova, there is an RPC call in the
conductor to backport objects, which is called when older code
gets an object it doesn’t understand. This patch does this in
Magnum:
<a moz-do-not-send="true"
href="https://review.openstack.org/#/c/184791/">https://review.openstack.org/#/c/184791/</a>
.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I can report bugs and propose patches with
version changes for this release, to get the effort started.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In Mitaka, when Grenade gets multi-node
support, it can be used to add CI tests for rolling upgrades
in Magnum.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">/ Greg<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<pre class="moz-signature" cols="72">--
Thanks,
Ryan Rossiter</pre>
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