08_custom-resources.yml

AWSTemplateFormatVersion: "2010-09-09"
Description: "DynamoDB zip codes and cities"

Resources:
  DynamoDbTable:
    Type: AWS::DynamoDB::Table
    Properties:
      AttributeDefinitions:
        - AttributeName: zip # declare zip as a string
          AttributeType: S
      KeySchema:
        - AttributeName: zip # declare zip as the partition key (hash)
          KeyType: HASH
      BillingMode: "PAY_PER_REQUEST"

  PrepopualateTable: # this key is arbitrary
    #Type: AWS::CloudFormation::CustomResource # could use generic form
    Type: Custom::LambdaPrepopulateTable # using semantic form
    DependsOn: DynamoDbTable
    Properties:
      # an Amazon SNS topic ARN or Lambda function ARN
      ServiceToken: !Sub arn:aws:lambda:${AWS::Region}:${AWS::AccountId}:function:prepop-dynamodb
      # arbitary key:values here
      TableARN: !GetAtt DynamoDbTable.Arn
    

      # CloudFormation REQUEST (http) or EVENT (lambda) will look something like this:
      # {
      #    "RequestType" : "Create",
      #    "ResponseURL" : "http://pre-signed-S3-url-for-response",
      #    "StackId" : "arn:aws:cloudformation:us-west-2:EXAMPLE/stack-name/guid",
      #    "RequestId" : "unique id for this create request",
      #    "ResourceType" : "Custom::LambdaPrepopulateTable",
      #    "LogicalResourceId" : "PrepopualateTable",
      #    "ResourceProperties" : {
      #       "TableARN" : "{dervied table arn}"
      #    }
      # }


      # Our lamba function's RESPONSE will look something like this:
      #
      # {
      #    "Status" : "SUCCESS",
      #    "PhysicalResourceId" : "TestResource1",
      #    "StackId" : "arn:aws:cloudformation:us-west-2:EXAMPLE:stack/stack-name/guid",
      #    "RequestId" : "unique id for this create request",
      #    "LogicalResourceId" : "PrepopualateTable",
      #    "Data" : {
      #       "OutputName1" : "Value1",
      #       "OutputName2" : "Value2",
      #    }
      # }