Fix charm for jujucharms.com use

hooks/install

 #!/usr/bin/env python2
 # -*- python -*-
 
 import json
-from subprocess import check_call
+import os
 
 # If the user's environment has "juju-origin: ppa" set, they will
 # automatically have access to python-charmhelpers and python-shelltoolbox.
 # However, we want to support environments that use the non-PPA environment as
 # well.  To do so, we need to install the Juju PPA, which we will do with a
 # couple of functions that are actually maintained in python-shelltoolbox.
 import bootstrap_utils
 
 
 def get_config():
     output = bootstrap_utils.run('config-get', '--format', 'json')
     return json.loads(output)
 
 config = get_config()
 allow_repos = config.get('allow-additional-deb-repositories', True)
 if allow_repos:
     bootstrap_utils.install_extra_repositories('ppa:juju/pkgs')
 
 # Python dependencies must be installed here so that the charm can import and
 # use required libraries.
 PYTHON_DEPENDENCIES = (
     'python-apt', 'python-charmhelpers', 'python-launchpadlib',
     'python-shelltoolbox', 'python-tempita',
 )
-check_call(('apt-get', 'install', '-y') + PYTHON_DEPENDENCIES)
+bootstrap_utils.run(*(('apt-get', 'install', '-y') + PYTHON_DEPENDENCIES))
 
 
 from utils import (
     config_json,
     log_hook,
 )
 
 from backend import Backend
 
 
 def main():
+    # Run pre-install tasks, if available.  Please do not rely on the
+    # exec.d interface without conferring with the Juju GUI team: it may
+    # change after upcoming discussion with Canonical IS.
+    if os.path.isdir('exec.d'):
+        for module in os.listdir('exec.d'):

[benji, 2013/04/27 20:29:30]

Usually ".d" files are to be run in lexicographic order, so throwing a sort()
around the listdir would be good.

[gary.poster, 2013/04/28 01:48:15]

Good idea in the abstract, and I changed it.

FWIW, this code is provided by IS for their use, and I don't like the pattern
and at least mew has agreed with me, so I'm not super excited about improving
it.  Your ideas were good, though, so I grudgingly did them anyway. :-)

+            try:
+                bootstrap_utils.run(os.path.join('exec.d',module,'charm-pre-install'))
+            except OSError:

[benji, 2013/04/27 20:29:30]

It would be safer if we knew which OSErrors in particular we should ignore.  It
would also be nice to know why we are ignoring them (i.e., a comment).

[gary.poster, 2013/04/28 01:48:15]

OK, good point...I did it, because I agree with you, though I had to guess at
their intent.  Hopefully I got it right. :-/

+                pass
     config = get_config()
     backend = Backend(config)
     backend.install()
     # Store current configuration.
     config_json.set(config)
 
 
 if __name__ == '__main__':
     with log_hook():
         main()