serverless.yml

service: callback-pattern-credit-check

plugins:
  - serverless-step-functions
  - serverless-pseudo-parameters

provider:
  name: aws
  runtime: python3.8
  stage: ${opt:stage, 'dev'}
  region: us-west-2
  logRetentionInDays: 7
  profile: contigoNew
  lambdaHashingVersion: 20201221
  iamRoleStatements:
    - Effect: Allow
      Action:
      - states:SendTaskFailure
      - states:SendTaskSuccess
      Resource: "*"
  environment:
    SENDMESSAGE_TO_EXTERNALSYSTEM: ${self:custom.SENDMESSAGE_TO_EXTERNALSYSTEM}
    QUEUE_URL_SENDMESSAGE_TO_EXTERNALSYSTEM : ${self:custom.QUEUE_URL_SENDMESSAGE_TO_EXTERNALSYSTEM}

custom:
  SENDMESSAGE_TO_EXTERNALSYSTEM: ${self:service}-${opt:stage,'dev'}-sendmessage_to_externalsystem
  QUEUE_URL_SENDMESSAGE_TO_EXTERNALSYSTEM : !Ref ExternalSystem
package:
  include:
  - handler.py

functions:
  CreditCheck:
    handler: handler.creditCheck
  Wallet:
    handler: handler.wallet
    events: 
      - sqs:
            arn: 
              Fn::GetAtt:
                - ExternalSystem
                - Arn

stepFunctions:
  stateMachines:
    CallbackExample:
      events: # start the state machine with a simulated event GET /start
        - http:
            path: start
            method: GET
      definition:
        StartAt: Credit Check
        States:
          Credit Check:
            Type: Task
            Resource:
              Fn::GetAtt: [CreditCheck,Arn]        
            Next: Wait For Complete # the happy path
          Wait For Complete:
            Type: Task
            Resource: arn:aws:states:::sqs:sendMessage.waitForTaskToken
            Parameters:
              QueueUrl: ${self:custom.QUEUE_URL_SENDMESSAGE_TO_EXTERNALSYSTEM}
              MessageBody: 
                input.$: "$"
                taskToken.$: "$$.Task.Token"
              # MessageAttributes:
              #   taskToken:
              #     DataType: String
              #     StringValue: $$.Task.Token            
            Next: Result # the happy path
          Result:
            Type: Choice
            Choices:
              - Variable: "$.credit_status"
                BooleanEquals: true
                Next: Approved
              - Variable: "$.credit_status"
                BooleanEquals: false
                Next: Denied
            Default: ErrorNotify
          Approved:
            Type: Pass
            Next: SendMessage 
          Denied:
            Type: Pass
            Next: SendMessage
          ErrorNotify:
            Type: Fail      
          SendMessage:
            Type: Pass 
            End: true 
resources:
  Resources:
    ExternalSystem:
      Type: "AWS::SQS::Queue"
      Properties:
        QueueName: "${self:custom.SENDMESSAGE_TO_EXTERNALSYSTEM}"