sam-template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: 'An AWS CloudFormation template for running scheduled tasks.'
Resources:
  ingestTopic:
    Type: 'AWS::SNS::Topic'
    Properties: {}
  tasksTable:
    Type: 'AWS::DynamoDB::Table'
    Properties:
      KeySchema:
        - AttributeName: taskId
          KeyType: HASH
      AttributeDefinitions:
        - AttributeName: taskId
          AttributeType: S
      ProvisionedThroughput:
        ReadCapacityUnits:
          Ref: ReadCapacityUnits
        WriteCapacityUnits:
          Ref: WriteCapacityUnits
  IngestFunction:
    Type: 'AWS::Serverless::Function'
    Properties:
      Handler: src/ingest.handler
      Runtime: nodejs20.x
      CodeUri: src
      MemorySize: 128
      Timeout: 3
      Policies:
        - Version: '2012-10-17'
          Statement:
            - Effect: Allow
              Action:
                - 'sns:Publish'
              Resource:
                Ref: DestinationArns
            - Effect: Allow
              Action:
                - 'dynamodb:UpdateItem'
                - 'dynamodb:Scan'
                - 'dynamodb:DeleteItem'
              Resource:
                'Fn::GetAtt':
                  - tasksTable
                  - Arn
      Environment:
        Variables:
          TASKS_TABLE:
            Ref: tasksTable
      Events:
        Event1:
          Type: SNS
          Properties:
            Topic:
              Ref: ingestTopic
  ScheduleFunction:
    Type: 'AWS::Serverless::Function'
    Properties:
      Handler: src/schedule.handler
      Runtime: nodejs20.x
      CodeUri: src
      MemorySize: 128
      Timeout: 60
      Policies:
        - Version: '2012-10-17'
          Statement:
            - Effect: Allow
              Action:
                - 'sns:Publish'
              Resource:
                Ref: DestinationArns
            - Effect: Allow
              Action:
                - 'dynamodb:UpdateItem'
                - 'dynamodb:Scan'
                - 'dynamodb:DeleteItem'
              Resource:
                'Fn::GetAtt':
                  - tasksTable
                  - Arn
      Environment:
        Variables:
          TASKS_TABLE:
            Ref: tasksTable
      Events:
        Event1:
          Type: Schedule
          Properties:
            Schedule:
              Ref: PollingSchedule
Outputs:
  IngestSNSTopicArn:
    Description: The ARN of the Ingest SNS topic
    Value:
      Ref: ingestTopic
Parameters:
  PollingSchedule:
    Default: rate(5 minutes)
    Type: String
    Description: >-
      The CloudWatch ScheduleExpression defining the interval the polling Lambda
      runs at.
  ReadCapacityUnits:
    Default: 1
    Type: Number
    Description: The read capacity units for the Scheduled Tasks DynamoDB table.
  WriteCapacityUnits:
    Default: 1
    Type: Number
    Description: The write capacity units for the Scheduled Tasks DynamoDB table.
  DestinationArns:
    Default: ''
    Type: CommaDelimitedList
    Description: >-
      A comma-separated list of possible destination SNS topic ARNs for
      permissioning the polling Lambda.