template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Form handler to initiate The Machine

# Config applied to all lambda functions.
Globals:
    Function:
        Timeout: 30
        Runtime: nodejs14.x
        Environment:
            Variables:
                REGISTRATION_TOPIC: !Ref RegistrationTopic
                REGISTRATION_TABLE: !Ref RegistrationTable

# Okay let's create stuff in AWS!
Resources:

  # This is the SNS topic we will pubish our registration events.
  RegistrationTopic:
    Type: AWS::SNS::Topic

  # This is where we will store the registration data.
  RegistrationTable:
    Type: AWS::DynamoDB::Table
    Properties:
      AttributeDefinitions:
        -
          AttributeName: "email"
          AttributeType: "S"
      KeySchema:
        -
          AttributeName: "email"
          KeyType: "HASH"
      ProvisionedThroughput:
        ReadCapacityUnits: "5"
        WriteCapacityUnits: "5"

  # This lambda function handles the form submission from the registrant.
  RegisterPostHandler:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: src/
      Handler: post.handler
      Events:
        Register:
          Type: Api
          Properties:
            Path: /register
            Method: post
      Policies:
        - SNSPublishMessagePolicy:
            TopicName: !GetAtt RegistrationTopic.TopicName

  # This lambda function consumes the event from SNS and saves the registration to the database.
  RegistrationTopicSubscriber:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: src/
      Handler: sns.handler
      Events:
        RegistrationEvent:
          Type: SNS
          Properties:
            Topic: !Ref RegistrationTopic
      Policies:
        - DynamoDBCrudPolicy:
            TableName: !Ref RegistrationTable

Outputs:
  RegistrationApi:
    Description: "API Gateway endpoint URL"
    Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/register/"