.. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. =================================== CloudFormation Compatible Functions =================================== There are a number of functions that you can use to help you write CloudFormation compatible templates. All of these functions (except *Ref*) start with *Fn::*. --- Ref --- Return the value of the named parameter or Resource. Parameters ~~~~~~~~~~ name : String The name of the Resource or Parameter. Usage ~~~~~ :: {Ref: my_server} Returns the nova instance ID. For example, ``d8093de0-850f-4513-b202-7979de6c0d55`` ---------- Fn::Base64 ---------- This returns the Base64 representation of the input string. Parameters ~~~~~~~~~~ value : String The string to convert. Usage ~~~~~ :: {Base64: "convert this string please."} Returns the Base64 of the input string. ------------- Fn::FindInMap ------------- Returns the value corresponding to keys into a two-level map declared in the Mappings section. Parameters ~~~~~~~~~~ map_name : String The logical name of a mapping declared in the Mappings section that contains the keys and values. top_level_key : String The top-level key name. It's value is a list of key-value pairs. second_level_key : String The second-level key name, which is set to one of the keys from the list assigned to top_level_key. Usage ~~~~~ :: Mapping: MyContacts: jone: {phone: 337, email: a@b.com} jim: {phone: 908, email: g@b.com} {"Fn::FindInMap": ["MyContacts", "jim", "phone" ] } Returns ``908`` ---------- Fn::GetAtt ---------- Returns an attribute of a Resource within the template. Parameters ~~~~~~~~~~ resource : String The name of the Resource. attribute : String The name of the attribute. Usage ~~~~~ :: {Fn::GetAtt: [my_server, PublicIp]} Returns an IP address such as ``10.0.0.2`` ---------- Fn::GetAZs ---------- Return the Availability Zones within the given region. *Note: AZ's and regions are not fully implemented in Heat.* Parameters ~~~~~~~~~~ region : String The name of the region. Usage ~~~~~ :: {Fn::GetAZs: ""} Returns the list provided by ``nova availability-zone-list`` -------- Fn::Join -------- Like python join, it joins a list of strings with the given delimiter. Parameters ~~~~~~~~~~ delimiter : String The string to join the list with. list : list The list to join. Usage ~~~~~ :: {Fn::Join: [",", ["beer", "wine", "more beer"]]} Returns ``beer, wine, more beer`` ---------- Fn::Select ---------- Select an item from a list. *Heat extension: Select an item from a map* Parameters ~~~~~~~~~~ selector : string or integer The number of item in the list or the name of the item in the map. collection : map or list The collection to select the item from. Usage ~~~~~ For a list lookup: :: { "Fn::Select" : [ "2", [ "apples", "grapes", "mangoes" ] ] } Returns ``mangoes`` For a map lookup: :: { "Fn::Select" : [ "red", {"red": "a", "flu": "b"} ] } Returns ``a`` --------- Fn::Split --------- This is the reverse of Join. Convert a string into a list based on the delimiter. Parameters ~~~~~~~~~~ delimiter : string Matching string to split on. string : String The string to split. Usage ~~~~~ :: { "Fn::Split" : [ ",", "str1,str2,str3,str4"]} Returns ``{["str1", "str2", "str3", "str4"]}`` ----------- Fn::Replace ----------- Find an replace one string with another. Parameters ~~~~~~~~~~ substitutions : map A map of substitutions. string: String The string to do the substitutions in. Usage ~~~~~ :: {"Fn::Replace": [ {'$var1': 'foo', '%var2%': 'bar'}, '$var1 is %var2%' ]} returns "foo is bar" ------------------ Fn::ResourceFacade ------------------ When writing a Template Resource: - user writes a template that will fill in for a resource (the resource is the facade). - when they are writing their template they need to access the metadata from the facade. Parameters ~~~~~~~~~~ attribute_name : String One of ``Metadata``, ``DeletionPolicy`` or ``UpdatePolicy``. Usage ~~~~~ :: {'Fn::ResourceFacade': 'Metadata'} {'Fn::ResourceFacade': 'DeletionPolicy'} {'Fn::ResourceFacade': 'UpdatePolicy'} Example ~~~~~~~ Here is a top level template ``top.yaml`` :: resources: my_server: type: OS::Nova::Server metadata: key: value some: more stuff Here is a resource template ``my_actual_server.yaml`` :: resources: _actual_server_: type: OS::Nova::Server metadata: {'Fn::ResourceFacade': Metadata} The environment file ``env.yaml`` :: resource_registry: resources: my_server: "OS::Nova::Server": my_actual_server.yaml To use it :: heat stack-create -f top.yaml -e env.yaml What happened is the metadata in ``top.yaml`` (key: value, some: more stuff) gets passed into the resource template via the `Fn::ResourceFacade`_ function. ------------------- Fn::MemberListToMap ------------------- Convert an AWS style member list into a map. Parameters ~~~~~~~~~~ key name: string The name of the key (normally "Name" or "Key") value name: string The name of the value (normally "Value") list: A list of strings The string to convert. Usage ~~~~~ :: {'Fn::MemberListToMap': ['Name', 'Value', ['.member.0.Name=key', '.member.0.Value=door', '.member.1.Name=colour', '.member.1.Value=green']]} returns {'key': 'door', 'colour': 'green'}