Improve version handling.

Improve version handling.

Modify the app.ensure_dependencies function 
so that it returns the Juju version tuple.
This way we allow for reusing the version 
through the app and we can avoid calling 
"juju version" multiple times.

Support local environments by installing
the juju-local meta-package in place of 
specific packages (e.g. lxc, mongo). 
This way we don't have to update quickstart
if core devs introduce new local env
dependencies.

Fix the destroy-environment message displayed
at the end of the process. The -e flag is
included when an old Juju is used.

Tests: `make check`.

QA: no strictly required.
Use .venv/bin/python juju-quickstart, check everything
works well, check the destroy-environment message
at the end of the process.

https://code.launchpad.net/~frankban/juju-quickstart/version-handling/+merge/210395

(do not edit description out of merge proposal)

[frankban, 2014-03-11 13:05:49]

Please take a look.

[rharding, 2014-03-11 13:24:24]

LGTM will qa as well.

https://codereview.appspot.com/74010044/diff/1/quickstart/settings.py
File quickstart/settings.py (right):

https://codereview.appspot.com/74010044/diff/1/quickstart/settings.py#newcode34
quickstart/settings.py:34: # The path to the Juju command.
can/should we get this via `which juju`? I guess it shouldn't change.

[rharding, 2014-03-11 13:43:38]

QA ok doing a local env post 1.17.2 thanks!

[frankban, 2014-03-11 13:49:48]

Thank you for the review!

https://codereview.appspot.com/74010044/diff/1/quickstart/settings.py
File quickstart/settings.py (right):

https://codereview.appspot.com/74010044/diff/1/quickstart/settings.py#newcode34
quickstart/settings.py:34: # The path to the Juju command.
On 2014/03/11 13:24:24, rharding wrote:
> can/should we get this via `which juju`? I guess it shouldn't change. 

We can but I am not sure we should. We call juju with sudo, and we use the
complete path for that security reason. AFAICT using `which` would reintroduce
the problem ,and at that point it would be easier to just call `juju`.

[matthew.scott, 2014-03-11 16:09:38]

LGTM, thanks for the clean-up!

[frankban, 2014-03-11 16:15:42]

*** Submitted:

Improve version handling.

Modify the app.ensure_dependencies function 
so that it returns the Juju version tuple.
This way we allow for reusing the version 
through the app and we can avoid calling 
"juju version" multiple times.

Support local environments by installing
the juju-local meta-package in place of 
specific packages (e.g. lxc, mongo). 
This way we don't have to update quickstart
if core devs introduce new local env
dependencies.

Fix the destroy-environment message displayed
at the end of the process. The -e flag is
included when an old Juju is used.

Tests: `make check`.

QA: no strictly required.
Use .venv/bin/python juju-quickstart, check everything
works well, check the destroy-environment message
at the end of the process.

R=rharding, matthew.scott
CC=
https://codereview.appspot.com/74010044

[frankban, 2014-03-11 16:24:14]

Thank you!