Mappings
The optional Mappings
section matches a key to a corresponding set of named
values. For example, if you want to set values based on a region, you can create a mapping
that uses the region name as a key and contains the values you want to specify for each
specific region. You use the Fn::FindInMap
intrinsic function to retrieve values
in a map.
You can't include parameters, pseudo parameters, or intrinsic functions in the
Mappings
section.
Syntax
The Mappings
section consists of the key name Mappings
. The
keys in mappings must be literal strings. The values can be String
or
List
types. The following example
shows a Mappings
section containing a single mapping named
Mapping01
(the logical name).
Within a mapping, each map is a key followed by another mapping. The key must be a map of name-value pairs and unique within the mapping. The name can contain only alphanumeric characters (A-Za-z0-9).
JSON
"Mappings" : { "Mapping01" : { "Key01" : { "Name" : "Value01" }, "Key02" : { "Name" : "Value02" }, "Key03" : { "Name" : "Value03" } } }
YAML
Mappings: Mapping01: Key01: Name: Value01 Key02: Name: Value02 Key03: Name: Value03
Examples
Basic mapping
The following example shows a Mappings
section
with a map RegionMap
, which contains five keys that map to name-value pairs
containing single string values. The keys are region names. Each name-value pair is the
AMI ID for the HVM64 AMI in the region represented by the key.
The name-value pairs have a name (HVM64 in the example) and a value. By naming the values, you can map more than one set of values to a key.
JSON
"Mappings" : { "RegionMap" : { "us-east-1" : { "HVM64" : "ami-0ff8a91507f77f867"}, "us-west-1" : { "HVM64" : "ami-0bdb828fd58c52235"}, "eu-west-1" : { "HVM64" : "ami-047bb4163c506cd98"}, "ap-southeast-1" : { "HVM64" : "ami-08569b978cc4dfa10"}, "ap-northeast-1" : { "HVM64" : "ami-06cd52961ce9f0d85"} } }
YAML
Mappings: RegionMap: us-east-1: "HVM64": "ami-0ff8a91507f77f867" us-west-1: "HVM64": "ami-0bdb828fd58c52235" eu-west-1: "HVM64": "ami-047bb4163c506cd98" ap-southeast-1: "HVM64": "ami-08569b978cc4dfa10" ap-northeast-1: "HVM64": "ami-06cd52961ce9f0d85"
Mapping with multiple values
The following example has region keys that are mapped to two sets of values: one named HVM64 and the other HVMG2.
JSON
"RegionMap" : { "us-east-1" : {"HVM64" : "ami-0ff8a91507f77f867", "HVMG2" : "ami-0a584ac55a7631c0c"}, "us-west-1" : {"HVM64" : "ami-0bdb828fd58c52235", "HVMG2" : "ami-066ee5fd4a9ef77f1"}, "eu-west-1" : {"HVM64" : "ami-047bb4163c506cd98", "HVMG2" : "ami-0a7c483d527806435"}, "ap-northeast-1" : {"HVM64" : "ami-06cd52961ce9f0d85", "HVMG2" : "ami-053cdd503598e4a9d"}, "ap-southeast-1" : {"HVM64" : "ami-08569b978cc4dfa10", "HVMG2" : "ami-0be9df32ae9f92309"} }
YAML
RegionMap: us-east-1: HVM64: ami-0ff8a91507f77f867 HVMG2: ami-0a584ac55a7631c0c us-west-1: HVM64: ami-0bdb828fd58c52235 HVMG2: ami-066ee5fd4a9ef77f1 eu-west-1: HVM64: ami-047bb4163c506cd98 HVMG2: ami-0a7c483d527806435 ap-northeast-1: HVM64: ami-06cd52961ce9f0d85 HVMG2: ami-053cdd503598e4a9d ap-southeast-1: HVM64: ami-08569b978cc4dfa10 HVMG2: ami-0be9df32ae9f92309
Return a value from a mapping
You can use the Fn::FindInMap
function to return a named value based on a specified key.
The following example template contains an Amazon EC2 resource whose ImageId
property is assigned by the FindInMap
function. The FindInMap
function specifies key as the region where the stack is created (using the AWS::Region pseudo parameter) and
HVM64
as the name of the value to map to.
JSON
{ "AWSTemplateFormatVersion" : "2010-09-09", "Mappings" : { "RegionMap" : { "us-east-1" : {"HVM64" : "ami-0ff8a91507f77f867", "HVMG2" : "ami-0a584ac55a7631c0c"}, "us-west-1" : {"HVM64" : "ami-0bdb828fd58c52235", "HVMG2" : "ami-066ee5fd4a9ef77f1"}, "eu-west-1" : {"HVM64" : "ami-047bb4163c506cd98", "HVMG2" : "ami-0a7c483d527806435"}, "ap-northeast-1" : {"HVM64" : "ami-06cd52961ce9f0d85", "HVMG2" : "ami-053cdd503598e4a9d"}, "ap-southeast-1" : {"HVM64" : "ami-08569b978cc4dfa10", "HVMG2" : "ami-0be9df32ae9f92309"} } }, "Resources" : { "myEC2Instance" : { "Type" : "AWS::EC2::Instance", "Properties" : { "ImageId" : { "Fn::FindInMap" : [ "RegionMap", { "Ref" : "AWS::Region" }, "HVM64"]}, "InstanceType" : "m1.small" } } } }
YAML
AWSTemplateFormatVersion: "2010-09-09" Mappings: RegionMap: us-east-1: HVM64: ami-0ff8a91507f77f867 HVMG2: ami-0a584ac55a7631c0c us-west-1: HVM64: ami-0bdb828fd58c52235 HVMG2: ami-066ee5fd4a9ef77f1 eu-west-1: HVM64: ami-047bb4163c506cd98 HVMG2: ami-0a7c483d527806435 ap-northeast-1: HVM64: ami-06cd52961ce9f0d85 HVMG2: ami-053cdd503598e4a9d ap-southeast-1: HVM64: ami-08569b978cc4dfa10 HVMG2: ami-0be9df32ae9f92309 Resources: myEC2Instance: Type: "AWS::EC2::Instance" Properties: ImageId: !FindInMap [RegionMap, !Ref "AWS::Region", HVM64] InstanceType: m1.small
Input parameter and FindInMap
You can use an input parameter with the Fn::FindInMap
function to refer
to a specific value in a map. For example, suppose you have a list of regions and
environment types that map to a specific AMI ID. You can select the AMI ID that your stack
uses by using an input parameter (EnvironmentType
). To determine the region,
use the AWS::Region
pseudo parameter, which gets the AWS Region in which you
create the stack.
JSON
{ "Parameters" : { "EnvironmentType": { "Description": "The environment type", "Type": "String", "Default": "test", "AllowedValues": ["prod", "test"], "ConstraintDescription": "must be a prod or test" } }, "Mappings" : { "RegionAndInstanceTypeToAMIID" : { "us-east-1": { "test": "ami-8ff710e2", "prod": "ami-f5f41398" }, "us-west-2" : { "test" : "ami-eff1028f", "prod" : "ami-d0f506b0" }, ...other regions and AMI IDs... } }, "Resources" : { ...other resources... }, "Outputs" : { "TestOutput" : { "Description" : "Return the name of the AMI ID that matches the region and environment type keys", "Value" : { "Fn::FindInMap" : [ "RegionAndInstanceTypeToAMIID", { "Ref" : "AWS::Region" }, { "Ref" : "EnvironmentType" } ]} } } }
YAML
Parameters: EnvironmentType: Description: The environment type Type: String Default: test AllowedValues: - prod - test ConstraintDescription: must be a prod or test Mappings: RegionAndInstanceTypeToAMIID: us-east-1: test: "ami-8ff710e2" prod: "ami-f5f41398" us-west-2: test: "ami-eff1028f" prod: "ami-d0f506b0" ...other regions and AMI IDs... Resources: ...other resources... Outputs: TestOutput: Description: Return the name of the AMI ID that matches the region and environment type keys Value: !FindInMap [RegionAndInstanceTypeToAMIID, !Ref "AWS::Region", !Ref EnvironmentType]