Rework how the Conditional class deals with undefined vars

Previously, the Conditional class did a simple check when an
AnsibleUndefinedVariable error was raised to see if certain strings were
present. This patch tries to be smarter by evaluating the variable contained
in the error string and compared to the defined/not defined conditionals in
the conditional string.

This also modifies the UndefinedError message from HostVars slightly to
match the format returned jinja2 in general, making it easier to match the
error message in the Conditional code.

Fixes #18514
This commit is contained in:
James Cammarata 2016-11-21 16:57:27 -06:00
parent 324702c38f
commit 81aa12eb1b
2 changed files with 43 additions and 10 deletions

View file

@ -19,6 +19,8 @@
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
import re
from jinja2.exceptions import UndefinedError
from ansible.compat.six import text_type
@ -27,6 +29,8 @@ from ansible.playbook.attribute import FieldAttribute
from ansible.template import Templar
from ansible.module_utils._text import to_native
DEFINED_REGEX = re.compile(r'(hostvars\[.+\]|[\w_]+)\s+(not\s+is|is|is\s+not)\s+(defined|undefined)')
class Conditional:
'''
@ -62,6 +66,18 @@ class Conditional:
when = self._get_parent_attribute('when', extend=True, prepend=True)
return when
def extract_defined_undefined(self, conditional):
results = []
cond = conditional
m = DEFINED_REGEX.search(cond)
while m:
results.append(m.groups())
cond = cond[m.end():]
m = DEFINED_REGEX.search(cond)
return results
def evaluate_conditional(self, templar, all_vars):
'''
Loops through the conditionals set on this object, returning
@ -121,14 +137,31 @@ class Conditional:
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:
# the templating failed, meaning most likely a variable was undefined. If we happened to be
# looking for an undefined variable, return True, otherwise fail
try:
# first we extract the variable name from the error message
var_name = re.compile(r"'(hostvars\[.+\]|[\w_]+)' is undefined").search(str(e)).groups()[0]
# next we extract all defined/undefined tests from the conditional string
def_undef = self.extract_defined_undefined(conditional)
# then we loop through these, comparing the error variable name against
# each def/undef test we found above. If there is a match, we determine
# whether the logic/state mean the variable should exist or not and return
# the corresponding True/False
for (du_var, logic, state) in def_undef:
# when we compare the var names, normalize quotes because something
# like hostvars['foo'] may be tested against hostvars["foo"]
if var_name.replace("'", '"') == du_var.replace("'", '"'):
# the should exist is a xor test between a negation in the logic portion
# against the state (defined or undefined)
should_exist = ('not' in logic) != (state == 'defined')
if should_exist:
return False
else:
return True
# as nothing above matched the failed var name, re-raise here to
# trigger the AnsibleUndefinedVariable exception again below
raise
except Exception as new_e:
raise AnsibleUndefinedVariable("error while evaluating conditional (%s): %s" % (original, e))

View file

@ -73,7 +73,7 @@ class HostVars(collections.Mapping):
'''
host = self._find_host(host_name)
if host is None:
raise UndefinedError("%s not found in hostvars" % host_name)
raise UndefinedError("'hostvars[\"%s\"]' is undefined" % host_name)
return self._variable_manager.get_vars(loader=self._loader, host=host, include_hostvars=False)