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Welcome to this demo on defining mappings in AWS CloudFormation. In this lesson you’ll learn what mappings are, why they matter, and how to declare and reference them using Fn::FindInMap (the short form: !FindInMap). Mappings are ideal for storing fixed lookup tables and other static configuration values so you don’t hard-code them across your template. Mappings store static key-value pairs inside a CloudFormation template and provide a deterministic lookup mechanism. Use them for environment-specific values, region-specific AMI IDs, or any configuration that varies by a known key but remains static for a given deployment. Below is an example template that defines two input Parameters and a Mappings block. The mapping keys correspond to the allowed values for the InputDeveloperName parameter. 
Parameters:
  InputBucketName:
    Type: String
    Description: Please enter your desired S3 bucket name
  InputDeveloperName:
    Type: String
    AllowedValues:
      - Arno
      - Alice

Mappings:
  DevMap:
    Arno:
      Field: "Quality Assurance"
    Alice:
      Field: "Backend Developer"

Resources:
  # Your resources go here
How this works:
  • Place the Mappings section near the top of the template (it’s common to declare Parameters and Mappings before Resources for readability).
  • Give the mapping a name (in this example: DevMap).
  • Under that name, define top-level keys (here: Arno and Alice).
  • For each key, include one or more named values (here: Field with a string value).
  • Because the mapping keys match the allowed parameter values for InputDeveloperName, you can reference the mapping based on the selected parameter value.
Example: injecting a mapped value into a resource property 
Resources:
  MyBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Ref InputBucketName
      Tags:
        - Key: DeveloperRole
          Value: !FindInMap [ DevMap, !Ref InputDeveloperName, Field ]
In this example, the Tag DeveloperRole will be set to the Field value mapped to the provided InputDeveloperName (either “Quality Assurance” or “Backend Developer”). Best practices and tips:
  • Use mappings for static configuration (region, environment, role, AMI IDs) to keep templates DRY and easier to maintain.
  • Keep mapping keys synchronized with Parameter AllowedValues when you want controlled, predictable lookups.
  • Prefer !FindInMap for lookups instead of long conditionals or repeated parameters.
FeatureUse caseExample
MappingsStatic lookups keyed by known valuesRegion-to-AMI mapping, developer role lookup
ParametersUser-supplied inputs or constrained valuesBucket names, allowed developer names
ConditionsDeploy resources conditionally based on parameters or mappingsCreate resources only in certain environments
If you run cfn-lint you may see a message like “Mapping ‘DevMap’ is defined but not used.” This is expected until you reference the mapping with !FindInMap in your template. Running a dry validation (aws cloudformation validate-template) or using a lint rule that checks references can help confirm correct usage.
References and further reading:

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