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# (c) 2012-2014, Michael DeHaan <michael.dehaan@gmail.com>
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
# Make coding more python3-ish
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
from jinja2.exceptions import UndefinedError
from ansible.compat.six import text_type
from ansible.errors import AnsibleError
from ansible.playbook.attribute import FieldAttribute
from ansible.template import Templar
class Conditional:
'''
This is a mix-in class, to be used with Base to allow the object
to be run conditionally when a condition is met or skipped.
'''
_when = FieldAttribute(isa='list', default=[])
def __init__(self, loader=None):
# when used directly, this class needs a loader, but we want to
# make sure we don't trample on the existing one if this class
# is used as a mix-in with a playbook base class
if not hasattr(self, '_loader'):
if loader is None:
raise AnsibleError("a loader must be specified when using Conditional() directly")
else:
self._loader = loader
super(Conditional, self).__init__()
def _validate_when(self, attr, name, value):
if not isinstance(value, list):
setattr(self, name, [ value ])
def evaluate_conditional(self, templar, all_vars):
'''
Loops through the conditionals set on this object, returning
False if any of them evaluate as such.
'''
# since this is a mixin, it may not have an underlying datastructure
# associated with it, so we pull it out now in case we need it for
# error reporting below
ds = None
if hasattr(self, '_ds'):
ds = getattr(self, '_ds')
try:
for conditional in self.when:
if not self._check_conditional(conditional, templar, all_vars):
return False
except Exception as e:
raise AnsibleError("The conditional check '%s' failed. The error was: %s" % (conditional, e), obj=ds)
return True
def _check_conditional(self, conditional, templar, all_vars):
'''
This method does the low-level evaluation of each conditional
set on this object, using jinja2 to wrap the conditionals for
evaluation.
'''
original = conditional
if conditional is None or conditional == '':
return True
if conditional in all_vars and '-' not in text_type(all_vars[conditional]):
conditional = all_vars[conditional]
# make sure the templar is using the variables specifed to this method
templar.set_available_variables(variables=all_vars)
conditional = templar.template(conditional)
if not isinstance(conditional, basestring) or conditional == "":
return conditional
# a Jinja2 evaluation that results in something Python can eval!
presented = "{%% if %s %%} True {%% else %%} False {%% endif %%}" % conditional
conditional = templar.template(presented, fail_on_undefined=False)
val = conditional.strip()
if val == presented:
# the templating failed, meaning most likely a
# variable was undefined. If we happened to be
# looking for an undefined variable, return True,
# otherwise fail
if "is undefined" in original:
return True
elif "is defined" in original:
return False
else:
raise AnsibleError("error while evaluating conditional: %s (%s)" % (original, presented))
elif val == "True":
return True
elif val == "False":
return False
else:
raise AnsibleError("unable to evaluate conditional: %s" % original)
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