modules/libjuju/juju/placement.py

   1 #
   2 # This module allows us to parse a machine placement directive into a
   3 # Placement object suitable for passing through the websocket API.
   4 #
   5 # Once https://bugs.launchpad.net/juju/+bug/1645480 is addressed, this
   6 # module should be deprecated.
   7 #
   8
   9 from .client import client
  10
  11 MACHINE_SCOPE = "#"
  12
  13
  14 def parse(directive):
  15     """
  16     Given a string in the format `scope:directive`, or simply `scope`
  17     or `directive`, return a Placement object suitable for passing
  18     back over the websocket API.
  19
  20     """
  21     if not directive:
  22         # Handle null case
  23         return None
  24
  25     if isinstance(directive, (list, tuple)):
  26         results = []
  27         for d in directive:
  28             results.extend(parse(d))
  29         return results
  30
  31     if isinstance(directive, (dict, client.Placement)):
  32         # We've been handed something that we can simply hand back to
  33         # the api. (Forwards compatibility)
  34         return [directive]
  35
  36     # Juju 2.0 can't handle lxc containers.
  37     directive = directive.replace('lxc', 'lxd')
  38
  39     if ":" in directive:
  40         # Planner has given us a scope and directive in string form
  41         scope, directive = directive.split(":")
  42         return [client.Placement(scope=scope, directive=directive)]
  43
  44     if directive.isdigit():
  45         # Planner has given us a machine id (we rely on juju core to
  46         # verify its validity.)
  47         return [client.Placement(scope=MACHINE_SCOPE, directive=directive)]
  48
  49     if "/" in directive:
  50         # e.g. "0/lxd/0"
  51         # https://github.com/juju/juju/blob/master/instance/placement_test.go#L29
  52         return [
  53             client.Placement(scope=MACHINE_SCOPE, directive=directive),
  54         ]
  55
  56     # Planner has probably given us a container type. Leave it up to
  57     # juju core to verify that it is valid.
  58     return [client.Placement(scope=directive)]