Support placement directives on bootstrap

Support placement directives on bootstrap

juju bootstrap will accept a single, optional
positional argument that will be parsed as a
placement directive. We currently only allow
unscoped placement directives at bootstrap.

https://code.launchpad.net/~axwalk/juju-core/lp1237709-bootstrap-placement/+merge/216971

(do not edit description out of merge proposal)

[axw, 2014-04-24 02:50:51]

Please take a look.

[wallyworld, 2014-04-24 03:10:01]

LGTM with a suggestion.
Also a drive by fix for
// Directive is a scope-specific placement idrective

would be great.

https://codereview.appspot.com/91740043/diff/1/cmd/juju/bootstrap.go
File cmd/juju/bootstrap.go (right):

https://codereview.appspot.com/91740043/diff/1/cmd/juju/bootstrap.go#newcode107
cmd/juju/bootstrap.go:107: if err != instance.ErrPlacementScopeMissing {
What happens if there's a different error other than ErrPlacementScopeMissing?
In that case we should just return that other error shouldn't we? ie there's a
difference between an unsupported placement directive and a placement directive
that doesn't parse due to some other error. Even if there's no other error that
can be returned (yet), reworking the conditional would make it explicit that we
are only interested in a specific case.

[axw, 2014-04-24 03:37:24]

Please take a look.

https://codereview.appspot.com/91740043/diff/1/cmd/juju/bootstrap.go
File cmd/juju/bootstrap.go (right):

https://codereview.appspot.com/91740043/diff/1/cmd/juju/bootstrap.go#newcode107
cmd/juju/bootstrap.go:107: if err != instance.ErrPlacementScopeMissing {
On 2014/04/24 03:10:01, wallyworld wrote:
> What happens if there's a different error other than ErrPlacementScopeMissing?
> In that case we should just return that other error shouldn't we? ie there's a
> difference between an unsupported placement directive and a placement
directive
> that doesn't parse due to some other error. Even if there's no other error
that
> can be returned (yet), reworking the conditional would make it explicit that
we
> are only interested in a specific case.

There are other errors, but they're not meaningful to us if we don't support
scoped placements. For example, lxc:non-numeric will fail to parse, but we
bootstrap doesn't care about why; it only cares that "lxc:anything" is not
supported by bootstrap.