DynamoDB Table Auto Scaling Enabled

Overview

This check verifies that DynamoDB tables can automatically scale their read and write capacity based on demand. Tables should use either on-demand capacity mode (which scales automatically) or provisioned capacity mode with auto scaling configured.

Risk

If DynamoDB tables cannot scale with demand, your applications may experience:

Throttling: Requests get rejected when capacity limits are exceeded
Degraded performance: Increased latency and timeouts
Cascading failures: Retry storms and request backlogs
Poor user experience: Application errors and slow response times

Remediation Steps

Prerequisites

You need permission to modify DynamoDB tables. Specifically, you need:

dynamodb:UpdateTable permission
For auto scaling: application-autoscaling:* permissions

Required IAM permissions (full list)

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "dynamodb:UpdateTable",
        "dynamodb:DescribeTable",
        "application-autoscaling:RegisterScalableTarget",
        "application-autoscaling:PutScalingPolicy",
        "application-autoscaling:DescribeScalableTargets",
        "application-autoscaling:DescribeScalingPolicies"
      ],
      "Resource": "*"
    }
  ]
}

Choose Your Approach

There are two ways to enable automatic scaling:

Approach	Best For	Cost Model
On-demand mode	Variable/unpredictable traffic	Pay per request
Provisioned + Auto Scaling	Predictable traffic patterns	Pay for provisioned capacity

Recommendation: If you are unsure which to choose, start with on-demand mode. It is simpler to set up and works well for most workloads.

Option 1: Enable On-Demand Mode (Recommended)

This is the simplest approach. DynamoDB automatically handles all capacity scaling.

AWS Console Method

Open the DynamoDB console
Select your table from the list
Click the Additional settings tab
In the Read/write capacity settings section, click Edit
Under Capacity mode, select On-demand
Click Save changes

The change takes effect immediately. Your table status will briefly show "Updating" and then return to "Active."

AWS CLI (optional)

aws dynamodb update-table \
    --table-name <your-table-name> \
    --billing-mode PAY_PER_REQUEST \
    --region us-east-1

Replace <your-table-name> with your actual table name.

Example:

aws dynamodb update-table \
    --table-name orders \
    --billing-mode PAY_PER_REQUEST \
    --region us-east-1

Option 2: Enable Provisioned Mode with Auto Scaling

Use this approach if you have predictable traffic and want more cost control.

AWS Console Method

Open the DynamoDB console
Select your table from the list
Click the Additional settings tab
In the Read/write capacity settings section, click Edit
Under Capacity mode, select Provisioned
For Read capacity, check Auto scaling
- Set Minimum capacity units (e.g., 5)
- Set Maximum capacity units (e.g., 100)
- Set Target utilization (e.g., 70%)
For Write capacity, check Auto scaling
- Set the same parameters as read capacity
Click Save changes

AWS CLI (optional)

Auto scaling with the CLI requires multiple commands. First, register scalable targets, then create scaling policies.

Step 1: Register scalable targets

# Register read capacity auto scaling
aws application-autoscaling register-scalable-target \
    --service-namespace dynamodb \
    --resource-id "table/<your-table-name>" \
    --scalable-dimension "dynamodb:table:ReadCapacityUnits" \
    --min-capacity 5 \
    --max-capacity 100 \
    --region us-east-1

# Register write capacity auto scaling
aws application-autoscaling register-scalable-target \
    --service-namespace dynamodb \
    --resource-id "table/<your-table-name>" \
    --scalable-dimension "dynamodb:table:WriteCapacityUnits" \
    --min-capacity 5 \
    --max-capacity 100 \
    --region us-east-1

Step 2: Create scaling policies

# Create read capacity scaling policy
aws application-autoscaling put-scaling-policy \
    --service-namespace dynamodb \
    --resource-id "table/<your-table-name>" \
    --scalable-dimension "dynamodb:table:ReadCapacityUnits" \
    --policy-name "DynamoDBReadAutoScalingPolicy" \
    --policy-type "TargetTrackingScaling" \
    --target-tracking-scaling-policy-configuration '{
        "TargetValue": 70.0,
        "PredefinedMetricSpecification": {
            "PredefinedMetricType": "DynamoDBReadCapacityUtilization"
        }
    }' \
    --region us-east-1

# Create write capacity scaling policy
aws application-autoscaling put-scaling-policy \
    --service-namespace dynamodb \
    --resource-id "table/<your-table-name>" \
    --scalable-dimension "dynamodb:table:WriteCapacityUnits" \
    --policy-name "DynamoDBWriteAutoScalingPolicy" \
    --policy-type "TargetTrackingScaling" \
    --target-tracking-scaling-policy-configuration '{
        "TargetValue": 70.0,
        "PredefinedMetricSpecification": {
            "PredefinedMetricType": "DynamoDBWriteCapacityUtilization"
        }
    }' \
    --region us-east-1

Replace <your-table-name> with your actual table name.

CloudFormation (optional)

On-demand mode (simple):

AWSTemplateFormatVersion: '2010-09-09'
Description: DynamoDB table with on-demand capacity mode

Resources:
  DynamoDBTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: my-table
      BillingMode: PAY_PER_REQUEST
      AttributeDefinitions:
        - AttributeName: pk
          AttributeType: S
      KeySchema:
        - AttributeName: pk
          KeyType: HASH
      Tags:
        - Key: Environment
          Value: Production

Provisioned mode with auto scaling:

AWSTemplateFormatVersion: '2010-09-09'
Description: DynamoDB table with provisioned capacity and auto scaling

Resources:
  DynamoDBTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: my-table
      BillingMode: PROVISIONED
      ProvisionedThroughput:
        ReadCapacityUnits: 5
        WriteCapacityUnits: 5
      AttributeDefinitions:
        - AttributeName: pk
          AttributeType: S
      KeySchema:
        - AttributeName: pk
          KeyType: HASH

  WriteScalableTarget:
    Type: AWS::ApplicationAutoScaling::ScalableTarget
    Properties:
      MaxCapacity: 100
      MinCapacity: 5
      ResourceId: !Sub table/${DynamoDBTable}
      RoleARN: !Sub arn:aws:iam::${AWS::AccountId}:role/aws-service-role/dynamodb.application-autoscaling.amazonaws.com/AWSServiceRoleForApplicationAutoScaling_DynamoDBTable
      ScalableDimension: dynamodb:table:WriteCapacityUnits
      ServiceNamespace: dynamodb

  ReadScalableTarget:
    Type: AWS::ApplicationAutoScaling::ScalableTarget
    Properties:
      MaxCapacity: 100
      MinCapacity: 5
      ResourceId: !Sub table/${DynamoDBTable}
      RoleARN: !Sub arn:aws:iam::${AWS::AccountId}:role/aws-service-role/dynamodb.application-autoscaling.amazonaws.com/AWSServiceRoleForApplicationAutoScaling_DynamoDBTable
      ScalableDimension: dynamodb:table:ReadCapacityUnits
      ServiceNamespace: dynamodb

  WriteScalingPolicy:
    Type: AWS::ApplicationAutoScaling::ScalingPolicy
    Properties:
      PolicyName: WriteAutoScalingPolicy
      PolicyType: TargetTrackingScaling
      ScalingTargetId: !Ref WriteScalableTarget
      TargetTrackingScalingPolicyConfiguration:
        TargetValue: 70.0
        PredefinedMetricSpecification:
          PredefinedMetricType: DynamoDBWriteCapacityUtilization

  ReadScalingPolicy:
    Type: AWS::ApplicationAutoScaling::ScalingPolicy
    Properties:
      PolicyName: ReadAutoScalingPolicy
      PolicyType: TargetTrackingScaling
      ScalingTargetId: !Ref ReadScalableTarget
      TargetTrackingScalingPolicyConfiguration:
        TargetValue: 70.0
        PredefinedMetricSpecification:
          PredefinedMetricType: DynamoDBReadCapacityUtilization

Terraform (optional)

On-demand mode (simple):

resource "aws_dynamodb_table" "example" {
  name         = "my-table"
  billing_mode = "PAY_PER_REQUEST"
  hash_key     = "pk"

  attribute {
    name = "pk"
    type = "S"
  }

  tags = {
    Environment = "Production"
  }
}

Provisioned mode with auto scaling:

resource "aws_dynamodb_table" "example" {
  name           = "my-table"
  billing_mode   = "PROVISIONED"
  read_capacity  = 5
  write_capacity = 5
  hash_key       = "pk"

  attribute {
    name = "pk"
    type = "S"
  }

  tags = {
    Environment = "Production"
  }
}

# Auto scaling for read capacity
resource "aws_appautoscaling_target" "read_target" {
  max_capacity       = 100
  min_capacity       = 5
  resource_id        = "table/${aws_dynamodb_table.example.name}"
  scalable_dimension = "dynamodb:table:ReadCapacityUnits"
  service_namespace  = "dynamodb"
}

resource "aws_appautoscaling_policy" "read_policy" {
  name               = "DynamoDBReadAutoScalingPolicy"
  policy_type        = "TargetTrackingScaling"
  resource_id        = aws_appautoscaling_target.read_target.resource_id
  scalable_dimension = aws_appautoscaling_target.read_target.scalable_dimension
  service_namespace  = aws_appautoscaling_target.read_target.service_namespace

  target_tracking_scaling_policy_configuration {
    predefined_metric_specification {
      predefined_metric_type = "DynamoDBReadCapacityUtilization"
    }
    target_value = 70.0
  }
}

# Auto scaling for write capacity
resource "aws_appautoscaling_target" "write_target" {
  max_capacity       = 100
  min_capacity       = 5
  resource_id        = "table/${aws_dynamodb_table.example.name}"
  scalable_dimension = "dynamodb:table:WriteCapacityUnits"
  service_namespace  = "dynamodb"
}

resource "aws_appautoscaling_policy" "write_policy" {
  name               = "DynamoDBWriteAutoScalingPolicy"
  policy_type        = "TargetTrackingScaling"
  resource_id        = aws_appautoscaling_target.write_target.resource_id
  scalable_dimension = aws_appautoscaling_target.write_target.scalable_dimension
  service_namespace  = aws_appautoscaling_target.write_target.service_namespace

  target_tracking_scaling_policy_configuration {
    predefined_metric_specification {
      predefined_metric_type = "DynamoDBWriteCapacityUtilization"
    }
    target_value = 70.0
  }
}

Verification

After making changes, verify that auto scaling is properly configured:

Open the DynamoDB console
Select your table
Click the Additional settings tab
Check the Read/write capacity settings section:
- For on-demand: Should show "On-demand" as the capacity mode
- For provisioned: Should show "Auto scaling" enabled for both read and write capacity

CLI verification commands

Check table billing mode:

aws dynamodb describe-table \
    --table-name <your-table-name> \
    --query "Table.BillingModeSummary.BillingMode" \
    --region us-east-1

Expected output for on-demand: "PAY_PER_REQUEST"

Check auto scaling targets (for provisioned mode):

aws application-autoscaling describe-scalable-targets \
    --service-namespace dynamodb \
    --resource-ids "table/<your-table-name>" \
    --region us-east-1

You should see entries for both ReadCapacityUnits and WriteCapacityUnits.

Additional Resources

Notes

Switching modes: You can switch between on-demand and provisioned modes, but there is a 24-hour cooldown period between switches in the same direction.
Global Secondary Indexes (GSIs): If your table has GSIs, they inherit the billing mode from the main table. For provisioned mode with auto scaling, you need to configure auto scaling separately for each GSI.
Cost considerations: On-demand mode is more expensive per request but simpler to manage. Provisioned mode with auto scaling can be more cost-effective for predictable workloads.
Scale-in cooldown: Auto scaling has a default 5-minute cooldown for scale-in actions to prevent rapid scaling fluctuations.

Overview​

Risk​

Remediation Steps​

Prerequisites​

Choose Your Approach​

Option 1: Enable On-Demand Mode (Recommended)​

AWS Console Method​

Option 2: Enable Provisioned Mode with Auto Scaling​

AWS Console Method​

Verification​

Additional Resources​

Notes​

Overview

Risk

Remediation Steps

Prerequisites

Choose Your Approach

Option 1: Enable On-Demand Mode (Recommended)

AWS Console Method

Option 2: Enable Provisioned Mode with Auto Scaling

AWS Console Method

Verification

Additional Resources

Notes