Make KVM respect constraints.

Make KVM respect constraints.

The uvtool CLI allows us to specify memory, disk
and cores on the command-line. Constraints often
ask for a subset (or superset) of these.

This branch translates between the juju constraints
format to the command line params that the uvt-kvm
tool wants.

If constraints are supplied that KVM doesn't support,
a log entry is written out at INFO level. It isn't
really a warning, just an informational that we are
ignoring it.

Also, the local provider wasn't passing the constraints
through as the FinishMachineConfig only set the constraints
on the config object if it was a state server node. I am
a little unclear on the implications of this for other
providers.

https://code.launchpad.net/~thumper/juju-core/kvm-constraints/+merge/197815

(do not edit description out of merge proposal)

[thumper, 2013-12-05 04:11:27]

Please take a look.

[wallyworld, 2013-12-05 04:23:31]

I have an issue with the early conversion of mem, cores etc to strings. Thoughts
on my comments?

I also think we need a todo and a comment to explain the machine config
constraints things since the cons is passed in to FinishMachineConfig and then
set and the reader will be confused without a comment. I think we should be able
to clean it up, hence a todo.

https://codereview.appspot.com/37610043/diff/1/container/kvm/kvm.go
File container/kvm/kvm.go (right):

https://codereview.appspot.com/37610043/diff/1/container/kvm/kvm.go#newcode30
container/kvm/kvm.go:30: DefaultDisk   uint64 = 8 // GB
Perhaps a comment about how we need opinionated defaults because blah blah

https://codereview.appspot.com/37610043/diff/1/container/kvm/libvirt.go
File container/kvm/libvirt.go (right):

https://codereview.appspot.com/37610043/diff/1/container/kvm/libvirt.go#newco...
container/kvm/libvirt.go:61: RootDisk      string
-1 to these as strings.
They should remain as ints and any formatting like sprintf should occur when the
command line args to uvt-kvm are generated

[thumper, 2013-12-05 22:34:33]

Please take a look.

https://codereview.appspot.com/37610043/diff/1/container/kvm/kvm.go
File container/kvm/kvm.go (right):

https://codereview.appspot.com/37610043/diff/1/container/kvm/kvm.go#newcode30
container/kvm/kvm.go:30: DefaultDisk   uint64 = 8 // GB
On 2013/12/05 04:23:31, wallyworld wrote:
> Perhaps a comment about how we need opinionated defaults because blah blah

Done.

https://codereview.appspot.com/37610043/diff/1/container/kvm/libvirt.go
File container/kvm/libvirt.go (right):

https://codereview.appspot.com/37610043/diff/1/container/kvm/libvirt.go#newco...
container/kvm/libvirt.go:61: RootDisk      string
On 2013/12/05 04:23:31, wallyworld wrote:
> -1 to these as strings.
> They should remain as ints and any formatting like sprintf should occur when
the
> command line args to uvt-kvm are generated

Done.

[wallyworld, 2013-12-05 23:11:46]

LGTM. Thanks for the changes