How to create DynamoDB table with autoscaled throughput via AWS SAM template

Question

I am trying to create a AWS SAM. My Lambda does some write operation on DynamoDB table and the table provisioned throughput should be Autoscaled. How can I mention in the template.yml file?

here is my table definition

Resources:
  myDB:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: my-awesome-database
      AttributeDefinitions:
        - AttributeName: e_id
          AttributeType: S
      KeySchema:
        - AttributeName: e_id
          KeyType: HASH
      GlobalSecondaryIndexes:
        - IndexName: my-awesome-database-index
          KeySchema:
            - AttributeName: es
              KeyType: HASH
            - AttributeName: ts
              KeyType: RANGE
          Projection:
            ProjectionType: ALL

Answer 1

Autoscaling of DynamoDB is not a property of DynamoDB. Instead, it is a property of Application Auto Scaling and you should use its resources to define scaling for your table.

An example for read-capacity auto-scaling with fixed table definition (your DynamoDB table is incorrect) is below. For auto-scaling write capacity you have to add similar resources.

Resources:
  myDB:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: my-awesome-database
      ProvisionedThroughput:
        ReadCapacityUnits: 2
        WriteCapacityUnits: 2      
      AttributeDefinitions:
        - AttributeName: e_id
          AttributeType: S
        - AttributeName: es
          AttributeType: S          
        - AttributeName: ts
          AttributeType: S          
      KeySchema:
        - AttributeName: e_id
          KeyType: HASH
      GlobalSecondaryIndexes:
        - IndexName: my-awesome-database-index
          KeySchema:
            - AttributeName: es
              KeyType: HASH
            - AttributeName: ts
              KeyType: RANGE
          Projection:
            ProjectionType: ALL
          ProvisionedThroughput:
            ReadCapacityUnits: 2
            WriteCapacityUnits: 2  

  MyScalableTarget:
    Type: AWS::ApplicationAutoScaling::ScalableTarget
    Properties: 
      MaxCapacity: 10
      MinCapacity: 1
      ResourceId: !Sub "table/${myDB}"
      RoleARN: !Sub "arn:aws:iam::${AWS::AccountId}:role/aws-service-role/dynamodb.application-autoscaling.amazonaws.com/AWSServiceRoleForApplicationAutoScaling_DynamoDBTable"
      ScalableDimension: dynamodb:table:ReadCapacityUnits
      ServiceNamespace: dynamodb

  MyScalableTargetGSI:
    Type: AWS::ApplicationAutoScaling::ScalableTarget
    Properties: 
      MaxCapacity: 10
      MinCapacity: 1
      ResourceId: !Sub "table/${myDB}/index/my-awesome-database-index"
      RoleARN: !Sub "arn:aws:iam::${AWS::AccountId}:role/aws-service-role/dynamodb.application-autoscaling.amazonaws.com/AWSServiceRoleForApplicationAutoScaling_DynamoDBTable"
      ScalableDimension: dynamodb:index:ReadCapacityUnits
      ServiceNamespace: dynamodb    

  MyTargetTracking:
    Type: AWS::ApplicationAutoScaling::ScalingPolicy
    Properties: 
      PolicyName: my-scaling-policy
      PolicyType: TargetTrackingScaling
      ScalingTargetId: !Ref MyScalableTarget
      TargetTrackingScalingPolicyConfiguration: 
        PredefinedMetricSpecification: 
          PredefinedMetricType: DynamoDBReadCapacityUtilization
        TargetValue: 70

  MyTargetTrackingGSI:
    Type: AWS::ApplicationAutoScaling::ScalingPolicy
    Properties: 
      PolicyName: my-scaling-policy
      PolicyType: TargetTrackingScaling
      ScalingTargetId: !Ref MyScalableTargetGSI
      TargetTrackingScalingPolicyConfiguration: 
        PredefinedMetricSpecification: 
          PredefinedMetricType: DynamoDBReadCapacityUtilization
        TargetValue: 70