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<p>I've recently been gathering feedback about the Magnum API and one of the things that people commented on was the global /containers endpoints. <span style="font-size: 12pt;">One person highlighted the danger of UUID collisions:</span></p>
<p><span style="font-size: 12pt;"><br>
</span></p>
<p><span style="font-size: 12pt;">"""</span></p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><span style="font-size: 12pt;">It takes a container ID which is intended to be unique within that individual cluster. Perhaps this doesn't matter, considering the surface for hash
collisions. You're running a 1% risk of collision on the shorthand container IDs:</span></p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><span style="font-size: 12pt;"><br>
</span></p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><span style="font-size: 12pt;">In [14]: n = lambda p,H: math.sqrt(2*H * math.log(1/(1-p)))<br>
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</span></p>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;">
In [15]: n(.01, 0x1000000000000)</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;">
Out[15]: 2378620.6298183016<br>
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<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><span style="font-size: 12pt;"><br>
</span></p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><span style="font-size: 12pt;">(this comes from the Birthday Attack - <a href="https://en.wikipedia.org/wiki/Birthday_attack" target="_blank">https://en.wikipedia.org/wiki/Birthday_attack)</a></span></p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><span style="font-size: 12pt;"><br>
</span></p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><span style="font-size: 12pt;">The main reason I questioned this is that we're not in control of how the hashes are created whereas each Docker node or Swarm cluster will pick a
new ID under collisions. We don't have that guarantee when aggregating across.</span></p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><br>
</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;">The use case that was outlined appears to be aggregation and reporting. That can be done in a different manner than programmatic access to single containers.<br>
</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;">"""<br>
</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><br>
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<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;">Representing a resource without reference to its parent resource also goes against the convention of many other OpenStack APIs.<br>
</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><br>
</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;">Nesting a container resource under its parent bay would mitigate both of these issues:<br>
</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><br>
</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;">/bays/{uuid}/containers/{uuid}<br>
</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><br>
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<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;">I'd like to get feedback from folks in the Magnum team and see if anybody has differing opinions about this.<br>
</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><br>
</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;">Jamie</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px;"><br>
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