Current File : //proc/self/root/usr/lib/python2.7/site-packages/ansible/playbook/conditional.py
# (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
import ast
import re
from jinja2.compiler import generate
from jinja2.exceptions import UndefinedError
from ansible.compat.six import text_type
from ansible.errors import AnsibleError, AnsibleUndefinedVariable
from ansible.playbook.attribute import FieldAttribute
from ansible.template import Templar
from ansible.module_utils._text import to_native
LOOKUP_REGEX = re.compile(r'lookup\s*\(')
VALID_VAR_REGEX = re.compile("^[_A-Za-z][_a-zA-Z0-9]*$")
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 _get_attr_when(self):
'''
Override for the 'tags' getattr fetcher, used from Base.
'''
when = self._attributes['when']
if when is None:
when = []
if hasattr(self, '_get_parent_attribute'):
when = self._get_parent_attribute('when', extend=True, prepend=True)
return when
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 mix-in, 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:
# this allows for direct boolean assignments to conditionals "when: False"
if isinstance(self.when, bool):
return self.when
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" % (to_native(conditional), to_native(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
# pull the "bare" var out, which allows for nested conditionals
# and things like:
# - assert:
# that:
# - item
# with_items:
# - 1 == 1
if conditional in all_vars and VALID_VAR_REGEX.match(conditional):
conditional = all_vars[conditional]
# make sure the templar is using the variables specified with this method
templar.set_available_variables(variables=all_vars)
try:
# if the conditional is "unsafe", disable lookups
disable_lookups = hasattr(conditional, '__UNSAFE__')
conditional = templar.template(conditional, disable_lookups=disable_lookups)
if not isinstance(conditional, text_type) or conditional == "":
return conditional
# update the lookups flag, as the string returned above may now be unsafe
# and we don't want future templating calls to do unsafe things
disable_lookups |= hasattr(conditional, '__UNSAFE__')
# now we generated the "presented" string, which is a jinja2 if/else block
# used to evaluate the conditional. First, we do some low-level jinja2 parsing
# involving the AST format of the statement to ensure we don't do anything
# unsafe (using the disable_lookup flag above)
e = templar.environment.overlay()
e.filters.update(templar._get_filters())
e.tests.update(templar._get_tests())
presented = "{%% if %s %%} True {%% else %%} False {%% endif %%}" % conditional
res = e._parse(presented, None, None)
res = generate(res, e, None, None)
parsed = ast.parse(res, mode='exec')
class CleansingNodeVisitor(ast.NodeVisitor):
def generic_visit(self, node, inside_call=False):
if isinstance(node, ast.Call):
inside_call = True
elif isinstance(node, ast.Str):
# calling things with a dunder is generally bad at this point...
if inside_call and disable_lookups and node.s.startswith("__"):
raise AnsibleError("Invalid access found in the presented conditional: '%s'" % conditional)
# iterate over all child nodes
for child_node in ast.iter_child_nodes(node):
self.generic_visit(child_node, inside_call=inside_call)
cnv = CleansingNodeVisitor()
cnv.visit(parsed)
# and finally we templated the presented string and look at the resulting string
val = templar.template(presented, disable_lookups=disable_lookups).strip()
if val == "True":
return True
elif val == "False":
return False
else:
raise AnsibleError("unable to evaluate conditional: %s" % original)
except (AnsibleUndefinedVariable, UndefinedError) as e:
# 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 or "is not defined" in original or "not is defined" in original:
return True
elif "is defined" in original or "is not undefined" in original or "not is undefined" in original:
return False
else:
raise AnsibleUndefinedVariable("error while evaluating conditional (%s): %s" % (original, e))
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