local: ensure that state and api ports are free

local: ensure that state and api ports are free

Evaluation of a way to ensure unused ports for state and API
of the local provider. In case a port is used the next one
is tried.

Caution: Only evaluation so far. Tests pass, but no explicit
tests for port conflicts. Will be added after discussion.

https://code.launchpad.net/~themue/juju-core/051-local-provider-ports/+merge/189812

(do not edit description out of merge proposal)

[mue, 2013-10-08 10:45:37]

Please take a look.

[mue, 2013-10-08 13:30:44]

Please take a look.

[fwereade, 2013-10-08 13:40:48]

yeah, that was roughly what I was thinking, but I'm not sure I thought it
through properly. It all depends on whether we still leave state-port and
api-port unset in the dict when we create a new Config -- and I'm not sure we
can sanely guarantee that behaviour.

Maybe best to just check and abort if the port's in use.

https://codereview.appspot.com/14527044/diff/3001/provider/local/environprovi...
File provider/local/environprovider.go (right):

https://codereview.appspot.com/14527044/diff/3001/provider/local/environprovi...
provider/local/environprovider.go:60: statePort, err :=
ensureLocalPort(cfg.StatePort())
If it's set explicitly, we shouldn't second-guess the user. Maybe that makes it
impossible?

[mue, 2013-10-14 15:02:58]

Please take a look.

https://codereview.appspot.com/14527044/diff/3001/provider/local/environprovi...
File provider/local/environprovider.go (right):

https://codereview.appspot.com/14527044/diff/3001/provider/local/environprovi...
provider/local/environprovider.go:60: statePort, err :=
ensureLocalPort(cfg.StatePort())
On 2013/10/08 13:40:48, fwereade wrote:
> If it's set explicitly, we shouldn't second-guess the user. Maybe that makes
it
> impossible?

Done.

[fwereade, 2013-11-05 15:46:54]

Yeah, I think this checks as much as we reasonably can. LGTM, thanks.