Step Functions SDK Integration - Nested Sync Express Workflow

hello_universe.asl.json

{
    "StartAt": "Sit and wait",
    "States": {
        "Sit and wait": {
            "Type": "Wait",
            "Seconds": 1,
            "Next": "Dummy Output"
        },
        "Dummy Output": {
            "Type": "Pass",
            "Result": {
                "hello": "world"
            },
            "End": true
        }
    }
}

hello_world.asl.json

{
    "StartAt": "Sit and wait",
    "States": {
        "Sit and wait": {
            "Type": "Wait",
            "Seconds": 1,
            "Next": "Dummy Output"
        },
        "Dummy Output": {
            "Type": "Pass",
            "Result": {
                "hello": "universe"
            },
            "End": true
        }
    }
}

main.asl.json

{
    "Comment": "Master express workflow",
    "StartAt": "Wait 3s",
    "States": {
        "Wait 3s": {
            "Comment": "A Wait state delays the state machine from continuing for a specified time.",
            "Type": "Wait",
            "Seconds": 3,
            "Next": "Nested workflows"
        },
        "Nested workflows": {
            "Comment": "A Parallel state can be used to create parallel branches of execution in your state machine.",
            "Type": "Parallel",
            "Next": "Bye",
            "ResultPath": "$.nested_result_combined",
            "Branches": [
                {
                    "StartAt": "HelloWorldWorkflow",
                    "States": {
                        "HelloWorldWorkflow": {
                            "Type": "Task",
                            "Resource": "arn:aws:states:::aws-sdk:sfn:startSyncExecution",
                            "Parameters": {
                                "StateMachineArn": "${HelloWorldWorkflow}",
                                "Input.$": "$"
                            },
                            "ResultSelector": {
                                "osrm.$": "States.StringToJson($.Output)"
                            },
                            "End": true
                        }
                    }
                },
                {
                    "StartAt": "HelloUniverseWorkflow",
                    "States": {
                        "HelloUniverseWorkflow": {
                            "Type": "Task",
                            "Resource": "arn:aws:states:::aws-sdk:sfn:startSyncExecution",
                            "Parameters": {
                                "StateMachineArn": "${HelloUniverseWorkflow}",
                                "Input.$": "$"
                            },
                            "ResultSelector": {
                                "orientation.$": "States.StringToJson($.Output)"
                            },
                            "End": true
                        }
                    }
                }
            ]
        },
        "Bye": {
            "Type": "Pass",
            "End": true
        }
    }
}

template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  Step Functions Express with nested workflow using native SDK integration

Parameters:
  LogRetentionInDays:
    Description: Expire CloudWatch Logs after X days
    Type: Number
    Default: 14

Resources:
##########################################################################
#   Workflows                                                            #
##########################################################################

  MainWorkflow:
    Type: AWS::Serverless::StateMachine # More info about State Machine Resource: https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-resource-statemachine.html
    Properties:
      DefinitionUri: main.asl.json
      Type: EXPRESS
      Role: !GetAtt MainWorkflowRole.Arn
      DefinitionSubstitutions:
        HelloWorldWorkflow: !Ref HelloWorldWorkflow
        HelloUniverseWorkflow: !Ref HelloUniverseWorkflow
      Tracing:
        Enabled: True
      Logging:
        Destinations:
          - CloudWatchLogsLogGroup:
              LogGroupArn: !GetAtt MainWorkflowLogs.Arn
        IncludeExecutionData: true  # debugging
        Level: 'ALL'

  HelloWorldWorkflow:
    Type: AWS::Serverless::StateMachine # More info about State Machine Resource: https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-resource-statemachine.html
    Properties:
      DefinitionUri: hello_world.asl.json
      Type: EXPRESS
      Role: !GetAtt HelloWorldWorkflowRole.Arn
      Tracing:
        Enabled: True
      Logging:
        Destinations:
          - CloudWatchLogsLogGroup:
              LogGroupArn: !GetAtt HelloWorldWorkflowLogs.Arn
        IncludeExecutionData: true  # debugging
        Level: 'ALL'

  HelloUniverseWorkflow:
    Type: AWS::Serverless::StateMachine # More info about State Machine Resource: https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-resource-statemachine.html
    Properties:
      DefinitionUri: hello_universe.asl.json
      Type: EXPRESS
      Role: !GetAtt HelloUniverseWorkflowRole.Arn
      Tracing:
        Enabled: True
      Logging:
        Destinations:
          - CloudWatchLogsLogGroup:
              LogGroupArn: !GetAtt HelloUniverseWorkflowLogs.Arn
        IncludeExecutionData: true  # debugging
        Level: 'ALL'

##########################################################################
#   Workflow Logs                                                        #
##########################################################################

  MainWorkflowLogs:
    Type: AWS::Logs::LogGroup
    Properties:
      LogGroupName: /stepfunctions/MainWorkflow
      RetentionInDays: !Ref LogRetentionInDays

  HelloWorldWorkflowLogs:
    Type: AWS::Logs::LogGroup
    Properties:
      LogGroupName: /stepfunctions/HelloWorldWorkflow
      RetentionInDays: !Ref LogRetentionInDays

  HelloUniverseWorkflowLogs:
    Type: AWS::Logs::LogGroup
    Properties:
      LogGroupName: /stepfunctions/HelloUniverseWorkflow
      RetentionInDays: !Ref LogRetentionInDays

##########################################################################
#   Roles                                                                #
##########################################################################

  MainWorkflowRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
          Version: 2012-10-17
          Statement:
              - Effect: Allow
                Principal:
                    Service: states.amazonaws.com
                Action: sts:AssumeRole
      Policies:
          - PolicyName: StartNestedWorkflows
            PolicyDocument:
              Version: 2012-10-17
              Statement:
                - Effect: Allow
                  Action: "states:StartSyncExecution"
                  Resource: 
                    - !Ref HelloWorldWorkflow
                    - !Ref HelloUniverseWorkflow
          - PolicyName: LogsPolicy
            PolicyDocument:
                Version: "2012-10-17"
                Statement:
                  - Effect: Allow
                    Action:
                      - "logs:CreateLogDelivery"
                      - "logs:GetLogDelivery"
                      - "logs:UpdateLogDelivery"
                      - "logs:DeleteLogDelivery"
                      - "logs:ListLogDeliveries"
                      - "logs:PutResourcePolicy"
                      - "logs:DescribeResourcePolicies"
                      - "logs:DescribeLogGroups"
                    Resource: 
                      - !GetAtt MainWorkflowLogs.Arn
          # Quick IAM reference: https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html
          - PolicyName: MetricsTracingPolicy
            PolicyDocument:
                Version: "2012-10-17"
                Statement:
                  - Effect: Allow
                    Action:
                      - "cloudwatch:PutMetricData"
                      - "xray:PutTraceSegments"
                      - "xray:PutTelemetryRecords"
                    Resource: "*"

  HelloWorldWorkflowRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
          Version: 2012-10-17
          Statement:
              - Effect: Allow
                Principal:
                    Service: states.amazonaws.com
                Action: sts:AssumeRole
      Policies:
          - PolicyName: LogsPolicy
            PolicyDocument:
                Version: "2012-10-17"
                Statement:
                  - Effect: Allow
                    Action:
                      - "logs:CreateLogDelivery"
                      - "logs:GetLogDelivery"
                      - "logs:UpdateLogDelivery"
                      - "logs:DeleteLogDelivery"
                      - "logs:ListLogDeliveries"
                      - "logs:PutResourcePolicy"
                      - "logs:DescribeResourcePolicies"
                      - "logs:DescribeLogGroups"
                    Resource: 
                      - !GetAtt HelloWorldWorkflowLogs.Arn
          # Quick IAM reference: https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html
          - PolicyName: MetricsTracingPolicy
            PolicyDocument:
                Version: "2012-10-17"
                Statement:
                  - Effect: Allow
                    Action:
                      - "cloudwatch:PutMetricData"
                      - "xray:PutTraceSegments"
                      - "xray:PutTelemetryRecords"
                    Resource: "*"


  HelloUniverseWorkflowRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
          Version: 2012-10-17
          Statement:
              - Effect: Allow
                Principal:
                    Service: states.amazonaws.com
                Action: sts:AssumeRole
      Policies:
          - PolicyName: LogsPolicy
            PolicyDocument:
                Version: "2012-10-17"
                Statement:
                  - Effect: Allow
                    Action:
                      - "logs:CreateLogDelivery"
                      - "logs:GetLogDelivery"
                      - "logs:UpdateLogDelivery"
                      - "logs:DeleteLogDelivery"
                      - "logs:ListLogDeliveries"
                      - "logs:PutResourcePolicy"
                      - "logs:DescribeResourcePolicies"
                      - "logs:DescribeLogGroups"
                    Resource: 
                      - !GetAtt HelloUniverseWorkflowLogs.Arn
          # Quick IAM reference: https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html
          - PolicyName: MetricsTracingPolicy
            PolicyDocument:
                Version: "2012-10-17"
                Statement:
                  - Effect: Allow
                    Action:
                      - "cloudwatch:PutMetricData"
                      - "xray:PutTraceSegments"
                      - "xray:PutTelemetryRecords"
                    Resource: "*"


##########################################################################
#   Outputs                                                              #
##########################################################################

Outputs:
  MainWorkflowArn:
    Description: "Main workflow ARN"
    Value: !Ref MainWorkflow

  HelloWorldWorkflowArn:
    Description: "Hello world workflow ARN"
    Value: !Ref HelloWorldWorkflow
  
  HelloUniverseWorkflowArn:
    Description: "Hello Universe workflow ARN"
    Value: !Ref HelloUniverseWorkflow