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 MACHINE_SCOPE = "#"
  10
  11 from .client import client
  12
  13 def parse(directive):
  14     """
  15     Given a string in the format `scope:directive`, or simply `scope`
  16     or `directive`, return a Placement object suitable for passing
  17     back over the websocket API.
  18
  19     """
  20     if directive == "":
  21         # Handle null case
  22         return None
  23
  24     if type(directive) in [dict, client.Placement]:
  25         # We've been handed something that we can simply hand back to
  26         # the api. (Forwards compatibility)
  27         return directive
  28
  29     if ":" in directive:
  30         # Planner has given us a scope and directive in string form
  31         scope, directive = directive.split(":")
  32         return client.Placement(scope=scope, directive=directive)
  33
  34     if directive.isdigit():
  35         # Planner has given us a machine id (we rely on juju core to
  36         # verify its validity.)
  37         return client.Placement(scope=MACHINE_SCOPE, directive=directive)
  38
  39     # Planner has probably given us a container type. Leave it up to
  40     # juju core to verify that it is valid.
  41     return client.Placement(scope=directive)