Open Stack

I've got Compute functionality working with the OpenStack Jenkins plugin,
so it can launch nova instances as on-demand slaves now, run builds on
them, and archive the results into  swift.  I'd like to open GitHub issues
to track your requirements, but I have a few questions.

> We need disposable machines that are only used for one test, which means
spinning up and terminating hundreds of machines per day.

Sounds like we want a function to terminate the machine after the job has
run.
https://github.com/platformlayer/openstack-jenkins/issues/1

> We need to use machines from multiple providers simultaneously so that
we're resilient against errors with one provider.

Label expressions should work here; you would apply a full set of axis
labels to each machine ("rax oneiric python26") but then you would filter
based only on the required axes ("oneric python26").  Are labels sufficient
for this?

> We need to pull nodes from a pool of machines that have been spun up
ahead of time for speed.

This sounds like a custom NodeProvisioner implementation.  The current
implementation is optimized around minimizing CPU hours, by doing load
prediction.  You have a different criteria, based on minimizing launch
latency.  It looks like it should be relatively easy to implement a new
algorithm, although perhaps a bit tricky to figure out how to plug it in.

https://github.com/platformlayer/openstack-jenkins/issues/2


> We need to be able to select from different kinds of images for certain
tests.

Are labels sufficient for this?

> Machines need to be checked for basic functionality before being added to
the pool (we frequently get nodes without a functioning network).

I believe Jenkins does this anyway; a node which doesn't have networking
won't be able to get the agent.  And you can run your own scripts after the
slave boots up ("apt-get install openjdk", for example).  Those scripts can
basically do any checks you want.  Is that enough?

> They need to be started from snapshots with cached data on them to avoid
false negatives from network problems.

Can you explain this a bit more?  This is to protect against the apt
repositories / python sources / github repos being down?  Would an http
proxy be enough?

> We need to keep them around after failures to diagnose problems, and we
 need to delete those after a certain amount of time.

>From the github docs, it sounds like you don't get access anyway because of
the providers' policies.  Would it not therefore be better to take a ZIP or
disk snapshot after a failed test, and then shut down the machine as normal?


Also...

You currently auto-update your images, which is cool
(devstack-update-vm-image).  Do you think this is something a plugin should
do, or do you think this is better done through scripts and a matrix job?
 I'm leaning towards keeping it in scripts.  The one thing I think we
definitely need here is some sort of 'best match' image launching, rather
than hard-coding to a particular ID, so that the cloud plugin will always
pick up the newest image.

https://github.com/platformlayer/openstack-jenkins/issues/3


Justin
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