AWS Step Functions with Serverless Example, including Re-Try policy, Parallel Execution and Error Handling.

serverless.yml

service: aws-step-functions-showcase

provider:
  name: aws
  runtime: nodejs8.10
  iamRoleStatements:
    - Effect: "Allow"
      Action:
        - "states:StartExecution"
      Resource:
        - "arn:aws:states:#{AWS::Region}:#{AWS::AccountId}:stateMachine:PDFTransform"
    - Effect: "Allow"
      Action:
        - "states:DescribeExecution"
      Resource:
        - "arn:aws:states:#{AWS::Region}:#{AWS::AccountId}:execution:PDFTransform:*"



functions:
  trigger:
    handler: handler.trigger
    events:
      - http: POST /trigger
    environment:
      STATE_MACHINE_ARN: "arn:aws:states:#{AWS::Region}:#{AWS::AccountId}:stateMachine:PDFTransform"
  status:
    handler: handler.status
    events:
      - http: GET /trigger
    environment:
      EXECUTION_ARN: "arn:aws:states:#{AWS::Region}:#{AWS::AccountId}:execution:PDFTransform:"
  convert:
    handler: handler.convert
  transform:
    handler: handler.transform
  thumbnail:
    handler: hander.thumbnail
  rollback:
    handler: handler.rollback


stepFunctions:
  stateMachines:
    pdfTransform:
      name: PDFTransform
      Description: "Takes vectorised PDFs and transforms them to PNGs with transparentbackground, also generates thumbnails for them."
      definition:
        StartAt: Convert
        States:
          Convert:
            Type: Task
            Next: Processing
            Resource: arn:aws:lambda:#{AWS::Region}:#{AWS::AccountId}:function:my-service-${opt:stage}-convert
            Retry:
              - ErrorEquals:
                  - States.TaskFailed
                IntervalSeconds: 30
                MaxAttempts: 2
                BackoffRate: 2
          Processing:
            Type: Parallel
            End: true
            Catch:
              - ErrorEquals:
                  - States.TaskFailed
                Next: Rollback
            Branches:
              - StartAt: Transform
                States:
                  Transform:
                    Type: Task
                    Resource: arn:aws:lambda:#{AWS::Region}:#{AWS::AccountId}:function:my-service-${opt:stage}-transform
                    End: true
              - StartAt: Thumbnail
                States:
                  Thumbnail:
                    Type: Task
                    Resource: arn:aws:lambda:#{AWS::Region}:#{AWS::AccountId}:function:my-service-${opt:stage}-thumbnail
                    End: true
          Rollback:
            Type: Task
            Resource: arn:aws:lambda:#{AWS::Region}:#{AWS::AccountId}:function:my-service-${opt:stage}-rollback 
            End: true

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