Serverless Lambda Destinations

serverless.yml

service: serverless-lambda-destinations
provider:
  name: aws
  runtime: nodejs12.x
  lambdaHashingVersion: 20201221
  memorySize: 128
  stage: ${opt:stage, 'develop'}
  region: eu-west-1
  apiGateway:
    shouldStartNameWithService: true
package:
  individually: true
functions:
  # lambda function invoked from sns topic async
  # i.e. api gateway -> sns -> lambda
  processPayment:
    handler: src/process-payment.handler
    maximumRetryAttempts: 0
    maximumEventAge: 60
    destinations:
      onSuccess: ${self:custom.successArn}
      onFailure: ${self:custom.failureArn}
    events:
      - sns:
          arn: !Ref PaymentsTopic
          topicName: PaymentsTopic
  # a lambda reading from the success sqs queue to send email to the customer
  notifyCustomer:
    handler: src/notify-customer.handler
    maximumRetryAttempts: 0
    maximumEventAge: 60
    events:
      - sqs:
          batchSize: 1 # in reality you would have your lambda batch process but setting to 1 for example
          maximumBatchingWindow: 1
          arn:
            Fn::GetAtt:
              - PaymentsNotification
              - Arn
  # a lambda reading from the sqs dlq to send email to the failed payments team
  notifyPaymentsTeam:
    handler: src/notify-payments-team.handler
    maximumRetryAttempts: 0
    maximumEventAge: 60
    events:
      - sqs:
          batchSize: 1 # in reality you would have your lambda batch process but setting to 1 for example
          maximumBatchingWindow: 1
          arn:
            Fn::GetAtt:
              - PaymentsDLQ
              - Arn
custom:
  successArn: arn:aws:sqs:${self:provider.region}:#{AWS::AccountId}:paymentsNotification
  failureArn: arn:aws:sqs:${self:provider.region}:#{AWS::AccountId}:paymentsDLQ
  apiGatewayServiceProxies:
    - sns:
        # payments endpoint in apig which will write directly to sns topic PaymentsTopic
        path: /payments
        method: post
        topicName: PaymentsTopic
        cors: true
        response:
          - statusCode: 200
            responseParameters: {}
            responseTemplates:
              application/json: |-
                { "message": "accepted" }
          - statusCode: 400
            responseParameters: {}
            responseTemplates:
              application/json: |-
                { "message": "there is an error in your request" }
          - statusCode: 500
            responseParameters: {}
            responseTemplates:
              application/json: |-
                { "message": "there was an error handling your request" }
resources:
  Resources:
    # creation of the payments topic (sns)
    PaymentsTopic:
      Type: AWS::SNS::Topic
      Properties:
        TopicName: PaymentsTopic
    # creation of the payments processing sqs dlq (dead letter queue)
    PaymentsDLQ:
      Type: AWS::SQS::Queue
      Properties:
        QueueName: paymentsDLQ
    # creation of the payments notifications queue for successful processing
    PaymentsNotification:
      Type: AWS::SQS::Queue
      Properties:
        QueueName: paymentsNotification
plugins:
  - serverless-apigateway-service-proxy
  - serverless-pseudo-parameters