The heat.engine.cfn.functions Module

class heat.engine.cfn.functions.Base64(stack, fn_name, args)

Bases: heat.engine.function.Function

A placeholder function for converting to base64.

Takes the form:

{ "Fn::Base64" : "<string>" }

This function actually performs no conversion. It is included for the benefit of templates that convert UserData to Base64. Heat accepts UserData in plain text.

result()

class heat.engine.cfn.functions.FindInMap(stack, fn_name, args)

Bases: heat.engine.function.Function

A function for resolving keys in the template mappings.

Takes the form:

{ "Fn::FindInMap" : [ "mapping",
                      "key",
                      "value" ] }

result()

class heat.engine.cfn.functions.GetAZs(stack, fn_name, args)

Bases: heat.engine.function.Function

A function for retrieving the availability zones.

Takes the form:

{ "Fn::GetAZs" : "<region>" }

result()

class heat.engine.cfn.functions.GetAtt(stack, fn_name, args)

Bases: heat.engine.function.Function

A function for resolving resource attributes.

Takes the form:

{ "Fn::GetAtt" : [ "<resource_name>",
                   "<attribute_name" ] }

dep_attrs(resource_name)

dependencies(path)

result()

validate()

class heat.engine.cfn.functions.Join(stack, fn_name, args)

Bases: heat.engine.function.Function

A function for joining strings.

Takes the form:

{ "Fn::Join" : [ "<delim>", [ "<string_1>", "<string_2>", ... ] ] }

And resolves to:

"<string_1><delim><string_2><delim>..."

result()

class heat.engine.cfn.functions.MemberListToMap(stack, fn_name, args)

Bases: heat.engine.function.Function

A function to convert lists with enumerated keys and values to mapping.

Takes the form:

{ 'Fn::MemberListToMap' : [ 'Name',
                            'Value',
                            [ '.member.0.Name=<key_0>',
                              '.member.0.Value=<value_0>',
                              ... ] ] }

And resolves to:

{ "<key_0>" : "<value_0>", ... }

The first two arguments are the names of the key and value.

result()

class heat.engine.cfn.functions.ParamRef(stack, fn_name, args)

Bases: heat.engine.function.Function

A function for resolving parameter references.

Takes the form:

{ "Ref" : "<param_name>" }

result()

heat.engine.cfn.functions.Ref(stack, fn_name, args)

A function for resolving parameters or resource references.

Takes the form:

{ "Ref" : "<param_name>" }

or:

{ "Ref" : "<resource_name>" }

class heat.engine.cfn.functions.Replace(stack, fn_name, args)

Bases: heat.engine.function.Function

A function for performing string substitutions.

Takes the form:

{ "Fn::Replace" : [
    { "<key_1>": "<value_1>", "<key_2>": "<value_2>", ... },
    "<key_1> <key_2>"
  ] }

And resolves to:

"<value_1> <value_2>"

This is implemented using python str.replace on each key. Longer keys are substituted before shorter ones, but the order in which replacements are performed is otherwise undefined.

result()

class heat.engine.cfn.functions.ResourceFacade(stack, fn_name, args)

Bases: heat.engine.function.Function

A function for retrieving data in a parent provider template.

A function for obtaining data from the facade resource from within the corresponding provider template.

Takes the form:

{ "Fn::ResourceFacade": "<attribute_type>" }

where the valid attribute types are “Metadata”, “DeletionPolicy” and “UpdatePolicy”.

DELETION_POLICY = 'DeletionPolicy'

METADATA = 'Metadata'

UPDATE_POLICY = 'UpdatePolicy'

result()

class heat.engine.cfn.functions.ResourceRef(stack, fn_name, args)

Bases: heat.engine.function.Function

A function for resolving resource references.

Takes the form:

{ "Ref" : "<resource_name>" }

dependencies(path)

result()

class heat.engine.cfn.functions.Select(stack, fn_name, args)

Bases: heat.engine.function.Function

A function for selecting an item from a list or map.

Takes the form (for a list lookup):

{ "Fn::Select" : [ "<index>", [ "<value_1>", "<value_2>", ... ] ] }

Takes the form (for a map lookup):

{ "Fn::Select" : [ "<index>", { "<key_1>": "<value_1>", ... } ] }

If the selected index is not found, this function resolves to an empty string.

result()

class heat.engine.cfn.functions.Split(stack, fn_name, args)

Bases: heat.engine.function.Function

A function for splitting strings.

Takes the form:

{ "Fn::Split" : [ "<delim>", "<string_1><delim><string_2>..." ] }

And resolves to:

[ "<string_1>", "<string_2>", ... ]

result()