worker/provisioner: safe mode

worker/provisioner: safe mode

A new environ setting provisioner-safe-mode is
introduced (default = false). If true, then the
environ provisioner will not stop instances that
it does not know about. I had to muck about a
little with the logic to handle dead machines
to get the starts to align.

See bug 1254729

This proposal is a continuation of https://codereview.appspot.com/32710043/
as originally proposed by Ian.

https://code.launchpad.net/~rogpeppe/juju-core/469-wallyworld-provisioner-safe-mode/+merge/196925

(do not edit description out of merge proposal)

[rog, 2013-11-27 15:37:52]

Please take a look.

[fwereade, 2013-11-27 15:48:11]

LGTM, just trivial comments.

If it applies cleanly against 1.16, please go ahead and land there too, so we
can go ahead with live testing and doc-updating.

https://codereview.appspot.com/34050043/diff/1/environs/config/config.go
File environs/config/config.go (right):

https://codereview.appspot.com/34050043/diff/1/environs/config/config.go#newc...
environs/config/config.go:481: // ProvisionerSafeMode returns true is the
provisioner should *not*
s/is the/if the/

https://codereview.appspot.com/34050043/diff/1/worker/provisioner/provisioner...
File worker/provisioner/provisioner_test.go (right):

https://codereview.appspot.com/34050043/diff/1/worker/provisioner/provisioner...
worker/provisioner/provisioner_test.go:741: func (s *ProvisionerSuite)
TestSafeModeChangeNotBlocking(c *gc.C) {
I don't think this is the right test name? And I'm not *really* sure what the
test gets us regardless, but I don't suppose it hurts...

[rog, 2013-11-27 15:55:00]

Please take a look.

https://codereview.appspot.com/34050043/diff/1/environs/config/config.go
File environs/config/config.go (right):

https://codereview.appspot.com/34050043/diff/1/environs/config/config.go#newc...
environs/config/config.go:481: // ProvisionerSafeMode returns true is the
provisioner should *not*
On 2013/11/27 15:48:12, fwereade wrote:
> s/is the/if the/

done, slightly differently.

https://codereview.appspot.com/34050043/diff/1/worker/provisioner/provisioner...
File worker/provisioner/provisioner_test.go (right):

https://codereview.appspot.com/34050043/diff/1/worker/provisioner/provisioner...
worker/provisioner/provisioner_test.go:741: func (s *ProvisionerSuite)
TestSafeModeChangeNotBlocking(c *gc.C) {
On 2013/11/27 15:48:12, fwereade wrote:
> I don't think this is the right test name? And I'm not *really* sure what the
> test gets us regardless, but I don't suppose it hurts...

deleted.