Merge "Modify 'if' Macro to allow optional properties"
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@ -414,7 +414,15 @@ The complete list of supported condition functions is::
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--------------------
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The key with value ``2021-04-16`` or ``wallaby`` indicates that the YAML
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document is a HOT template and it may contain features added and/or removed
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up until the Wallaby release. The complete list of supported functions is::
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up until the Wallaby release.
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This version adds a 2-argument variant of the ``if`` function. When the
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condition is false and no third argument is supplied, the entire enclosing item
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(which may be e.g. a list item, a key-value pair in a dict, or a property
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value) will be elided. This allows for e.g. conditional definition of
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properties while keeping the default value when the condition is false.
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The complete list of supported functions is::
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digest
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filter
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@ -1875,6 +1883,27 @@ template except for ``if`` conditions. You can use the ``if`` condition
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in the property values in the ``resources`` section and ``outputs`` sections
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of a template.
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Beginning with the ``wallaby`` template version, the third argument is
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optional. If only two arguments are passed, the entire enclosing item is
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removed when the condition is false.
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For example:
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.. code-block:: yaml
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conditions:
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override_name: {not: {equals: [{get_param: server_name}, ""]}}
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resources:
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test_server:
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type: OS::Nova::Server
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properties:
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name: {if: [override_name, {get_param: server_name}]}
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In this example, the default name for the server (which is generated by Heat
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when the property value is not specified) would be used when the
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``server_name`` parameter value is an empty string.
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not
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---
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The ``not`` function acts as a NOT operator.
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@ -1275,13 +1275,16 @@ class If(function.Macro):
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evaluates to false.
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"""
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def _read_args(self):
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return self.args
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def parse_args(self, parse_func):
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try:
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if (not self.args or
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not isinstance(self.args, collections.Sequence) or
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isinstance(self.args, str)):
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raise ValueError()
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condition, value_if_true, value_if_false = self.args
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condition, value_if_true, value_if_false = self._read_args()
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except ValueError:
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msg = _('Arguments to "%s" must be of the form: '
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'[condition_name, value_if_true, value_if_false]')
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@ -1299,6 +1302,40 @@ class If(function.Macro):
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return self.template.conditions(self.stack).is_enabled(cond)
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class IfNullable(If):
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"""A function to return corresponding value based on condition evaluation.
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Takes the form::
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if:
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- <condition_name>
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- <value_if_true>
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- <value_if_false>
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The value_if_true to be returned if the specified condition evaluates
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to true, the value_if_false to be returned if the specified condition
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evaluates to false.
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If the value_if_false is omitted and the condition is false, the enclosing
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item (list item, dictionary key/value pair, property definition) will be
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treated as if it were not mentioned in the template::
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if:
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- <condition_name>
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- <value_if_true>
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"""
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def _read_args(self):
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if not (2 <= len(self.args) <= 3):
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raise ValueError()
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if len(self.args) == 2:
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condition, value_if_true = self.args
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return condition, value_if_true, Ellipsis
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return self.args
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class ConditionBoolean(function.Function):
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"""Abstract parent class of boolean condition functions."""
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@ -783,7 +783,8 @@ class HOTemplate20210416(HOTemplate20180831):
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# functions added in 2016-10-14
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'yaql': hot_funcs.Yaql,
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'map_replace': hot_funcs.MapReplace,
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'if': hot_funcs.If,
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# Modified in 2021-04-16
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'if': hot_funcs.IfNullable,
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# functions added in 2017-02-24
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'filter': hot_funcs.Filter,
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@ -71,6 +71,10 @@ hot_pike_tpl_empty = template_format.parse('''
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heat_template_version: 2017-09-01
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''')
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hot_wallaby_tpl_empty = template_format.parse('''
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heat_template_version: 2021-04-16
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''')
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hot_tpl_empty_sections = template_format.parse('''
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heat_template_version: 2013-05-23
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parameters:
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@ -1506,14 +1510,43 @@ resources:
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self.assertEqual('', self.stack['AResource'].properties['Foo'])
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def test_if_invalid_args(self):
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snippet = {'if': ['create_prod', 'one_value']}
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snippets = [
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{'if': ['create_prod', 'one_value']},
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{'if': ['create_prod', 'one_value', 'two_values', 'three_values']},
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]
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tmpl = template.Template(hot_newton_tpl_empty)
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for snippet in snippets:
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exc = self.assertRaises(exception.StackValidationFailed,
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self.resolve, snippet, tmpl)
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self.assertIn('Arguments to "if" must be of the form: '
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'[condition_name, value_if_true, value_if_false]',
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str(exc))
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def test_if_nullable_invalid_args(self):
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snippets = [
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{'if': ['create_prod']},
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{'if': ['create_prod', 'one_value', 'two_values', 'three_values']},
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]
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tmpl = template.Template(hot_wallaby_tpl_empty)
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for snippet in snippets:
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exc = self.assertRaises(exception.StackValidationFailed,
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self.resolve, snippet, tmpl)
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self.assertIn('Arguments to "if" must be of the form: '
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'[condition_name, value_if_true, value_if_false]',
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str(exc))
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def test_if_nullable(self):
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snippet = {
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'single': {'if': [False, 'value_if_true']},
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'nested_true': {'if': [True, {'if': [False, 'foo']}, 'bar']},
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'nested_false': {'if': [False, 'baz', {'if': [False, 'quux']}]},
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'control': {'if': [False, True, None]},
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}
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tmpl = template.Template(hot_wallaby_tpl_empty)
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resolved = self.resolve(snippet, tmpl, None)
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self.assertEqual({'control': None}, resolved)
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def test_if_condition_name_non_existing(self):
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snippet = {'if': ['cd_not_existing', 'value_true', 'value_false']}
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tmpl = template.Template(hot_newton_tpl_empty)
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@ -0,0 +1,8 @@
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---
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features:
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- |
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The ``wallaby`` template version introduces a new 2-argument form of the
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``if`` function. This allows users to specify optional property values, so
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that when the condition is false Heat treats it the same as if no value
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were specified for the property at all. The behaviour of existing templates
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is unchanged, even after updating the template version to ``wallaby``.
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