manage unittest slaves with pooling infrastructure

The Jclouds plugin is now used on jenkins.openstack.org to supplement the permanent Oneiric and Precise Jenkins slaves. New Oneiric and Precise slaves are spun up on demand by Jclouds when Jenkins doesn't have any remaining permanent slaves. These Jclouds slaves then stick around for 45 minutes after their last build.

Outstanding work that remains before this bug can be closed is making this work with Quantal. Rackspace and Jclouds apparently can't agree on how to boot a Quantal image.

The metadata for the Quantal image in Rackspace seems to be incorrect/insufficient. This has been informally escalated to their Cloud Images Team, but I haven't heard anything back yet. I'm continuing to retry and will check back with them soon if it isn't resolved.

We could extend devstack-gate to support this.

Also, we have a workaround to do quantal in rackspace via jenkins-jclouds as of a couple weeks ago, if it's needed.

We have disabled the Jclouds plugin as it wasn't able to consistently spin up slaves that were ready for testing before Jenkins used them. We will probably need a pool manager like devstack-gate to get this going again.

Status report. Jim write nodepool to manage our devstack gate nodes and dynamically balance them and so on. This new tool is full of fun features and we should give a shot at managing our unittest slaves with nodepool as well. This may require adding features to nodepool to allow for longer lived slaves, but adding features to nodepool should be straightforward.

Nodepool is currently managing single use precise slaves for unittest jobs in some projects. We now need to get nodepool working on fedora/centos in order to replace the static centos slaves. (note we are not replacing centos with fedora, but fedora and centos need a lot of the same fixes in nodepool and the nodepool scripts).

Currently working on getting Fedora working with nodepool, progress being tracked here (several reviews pending): https://etherpad.openstack.org/p/fedora-on-gate

We did get it working on CentOS just fine and are now using it. Since we currently don't have any static slaves running Fedora anyway that shouldn't be a blocker for closing this bug.

Closing this bug since it is working now with our current infrastructure with CentOS. Changes to support something like Fedora will be made in a follow-up bug.