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 type(directive) in [dict, client.Placement]:
  26         # We've been handed something that we can simply hand back to
  27         # the api. (Forwards compatibility)
  28         return [directive]
  29
  30     # Juju 2.0 can't handle lxc containers.
  31     directive = directive.replace('lxc', 'lxd')
  32
  33     if ":" in directive:
  34         # Planner has given us a scope and directive in string form
  35         scope, directive = directive.split(":")
  36         return [client.Placement(scope=scope, directive=directive)]
  37
  38     if directive.isdigit():
  39         # Planner has given us a machine id (we rely on juju core to
  40         # verify its validity.)
  41         return [client.Placement(scope=MACHINE_SCOPE, directive=directive)]
  42
  43     if "/" in directive:
  44         machine, container, container_num = directive.split("/")
  45         return [
  46             client.Placement(scope=MACHINE_SCOPE, directive=machine),
  47             client.Placement(scope=container, directive=container_num)
  48         ]
  49
  50     # Planner has probably given us a container type. Leave it up to
  51     # juju core to verify that it is valid.
  52     return [client.Placement(scope=directive)]