#
# Module that parses constraints
#
# The current version of juju core expects the client to take
# constraints given in the form "mem=10G foo=bar" and parse them into
# json that looks like {"mem": 10240, "foo": "bar"}. This module helps us
# accomplish that task.
#
# We do not attempt to duplicate the checking done in
# client/_client.py:Value here. That class will verify that the
# constraints keys are valid, and that we can successfully dump the
# constraints dict to json.
#
# Once https://bugs.launchpad.net/juju/+bug/1645402 is addressed, this
# module should be deprecated.
#
import re
# Matches on a string specifying memory size
MEM = re.compile('^[1-9][0-9]*[MGTP]$')
# Multiplication factors to get Megabytes
# https://github.com/juju/juju/blob/master/constraints/constraints.go#L666
FACTORS = {
"M": 1,
"G": 1024,
"T": 1024 * 1024,
"P": 1024 * 1024 * 1024
}
SNAKE1 = re.compile(r'(.)([A-Z][a-z]+)')
SNAKE2 = re.compile('([a-z0-9])([A-Z])')
[docs]def parse(constraints):
"""
Constraints must be expressed as a string containing only spaces
and key value pairs joined by an '='.
"""
if not constraints:
return None
if type(constraints) is dict:
# Fowards compatibilty: already parsed
return constraints
constraints = {
normalize_key(k): normalize_value(v) for k, v in [
s.split("=") for s in constraints.split(" ")]}
return constraints
[docs]def normalize_key(key):
key = key.strip()
key = key.replace("-", "_") # Our _client lib wants "_" in place of "-"
# Convert camelCase to snake_case
key = SNAKE1.sub(r'\1_\2', key)
key = SNAKE2.sub(r'\1_\2', key).lower()
return key
[docs]def normalize_value(value):
value = value.strip()
if MEM.match(value):
# Translate aliases to Megabytes. e.g. 1G = 10240
return int(value[:-1]) * FACTORS[value[-1:]]
if "," in value:
# Handle csv strings.
values = value.split(",")
values = [normalize_value(v) for v in values]
return values
if value.isdigit():
return int(value)
return value