Missing calls to parse_constraints in model.py

[petevg]

Looks like we missed some places where we need to parse constraints that we get back from the planner in in model.py.

To reproduce:

1. Deploy the landscape bundle
2. Note the following traceback (actual traceback from matrix, but the problem is in python-libjuju):

matrix:170:execute: Error in Rule(task=Task(command='matrix.tasks.deploy', args={}), conditions=[])'s task Task(command='matrix.tasks.deploy', args={})
Traceback (most recent call last):
  File "/home/petevg/Code/matrix/matrix/model.py", line 164, in execute
    result = await self.execute_plugin(context, cmd, rule)
  File "/home/petevg/Code/matrix/matrix/model.py", line 181, in execute_plugin
    result = await cmd(context, rule, self, event)
  File "/home/petevg/Code/matrix/matrix/tasks/deploy.py", line 5, in deploy
    await context.juju_model.deploy(str(context.config.path))
  File "/home/petevg/Code/matrix/.tox/py35/lib/python3.5/site-packages/juju/model.py", line 880, in deploy
    await handler.execute_plan()
  File "/home/petevg/Code/matrix/.tox/py35/lib/python3.5/site-packages/juju/model.py", line 1314, in execute_plan
    result = await method(*step.args)
  File "/home/petevg/Code/matrix/.tox/py35/lib/python3.5/site-packages/juju/model.py", line 1442, in deploy
    resources=resources,
  File "/home/petevg/Code/matrix/.tox/py35/lib/python3.5/site-packages/juju/client/_client.py", line 620, in __init__
    self.constraints = Value.from_json(constraints) if constraints else None
  File "/home/petevg/Code/matrix/.tox/py35/lib/python3.5/site-packages/juju/client/facade.py", line 442, in from_json
    data = json.loads(data)
  File "/usr/lib/python3.5/json/__init__.py", line 319, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.5/json/decoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.5/json/decoder.py", line 357, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
matrix:313:run_once: Pending tasks remain, aborting due to failure
matrix:322:run_once: Exception processing test: deployment
Traceback for <Task finished coro=<RuleEngine.rule_runner() done, defined at /home/petevg/Code/matrix/matrix/rules.py:175> exception=JSONDecodeError('Expecting value: line 1 column 1 (char 0)',)> (most recent call last):
  File "/usr/lib/python3.5/asyncio/tasks.py", line 292, in _step
    self = None  # Needed to break cycles when an exception occurs.
  File "/home/petevg/Code/matrix/matrix/rules.py", line 263, in rule_runner
    break
  File "/home/petevg/Code/matrix/matrix/model.py", line 344, in execute
    result = await self.task.execute(context, self)
  File "/home/petevg/Code/matrix/matrix/model.py", line 171, in execute
    raise
  File "/home/petevg/Code/matrix/matrix/model.py", line 181, in execute_plugin
    result = await cmd(context, rule, self, event)
  File "/home/petevg/Code/matrix/matrix/tasks/deploy.py", line 5, in deploy
    await context.juju_model.deploy(str(context.config.path))
  File "/home/petevg/Code/matrix/.tox/py35/lib/python3.5/site-packages/juju/model.py", line 880, in deploy
    await handler.execute_plan()
  File "/home/petevg/Code/matrix/.tox/py35/lib/python3.5/site-packages/juju/model.py", line 1314, in execute_plan
    result = await method(*step.args)
  File "/home/petevg/Code/matrix/.tox/py35/lib/python3.5/site-packages/juju/model.py", line 1442, in deploy
    resources=resources,
  File "/home/petevg/Code/matrix/.tox/py35/lib/python3.5/site-packages/juju/client/_client.py", line 620, in __init__
    self.constraints = Value.from_json(constraints) if constraints else None
  File "/home/petevg/Code/matrix/.tox/py35/lib/python3.5/site-packages/juju/client/facade.py", line 442, in from_json
    data = json.loads(data)
  File "/usr/lib/python3.5/json/__init__.py", line 319, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.5/json/decoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.5/json/decoder.py", line 357, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

[petevg]

Fixing this should be as simple as finding instances of the string "constraints" in model.py, and replacing where appropriate with parse_constraints(constraints).

[petevg]

Working on this now. It looks like it's not as simple as naively adding parse_constraints -- I get errors on the core side, and may have to make the logic in parse_constraints more sophisticated. :-/

[petevg]

This bug has unveiled a whole tangle of fun issues:

1. We needed to parse_constraints in more places -- I've done that locally.
2. We need to convert CamelCase in the AddMachines params to snake_case -- I've done that locally, though the code needs some neatening up.
3. If a .yaml specifies an lxd container or a machine, we need to parse that into two Placement objects -- I've done that locally.
4. If a .yaml specifies lxc containers, it looks like we need to setup lxd containers instead. I'm working on that, though my first pass at a fix isn't working :-/

[petevg]

Update: I've addressed point 4, from the previous comment, in a branch, but I'm now getting a failure getting haproxy up. Either there's a bug in 3 (Placement objects aren't making lxd containers correctly), or we're missing something that haproxy needs (it looks like it's complaining about missing a config value).

Will continue to work on this ...

[petevg]

A lot of this issue was fixed in #37

The remaining issue is open in launchpad here: https://bugs.launchpad.net/juju-core/+bug/1651260

Will open a new issue here if we need to do more work after addressing the launchpad bug.