Finish workflow
Complete the workflow
For now, we still leave the Approve Application and Reject Application states empty, (using the Pass state, not performing a specific action). We will replace these states with Tast states that call the appropriate Lambda functions.
In this step we will:
- Change the Approve Application and Reject Application state from Pass state to Task state and call the appropriate Lambda functions.
- Grant additional permissions to the IAM Role that Step Functions executes so that it can call the necessary Lambda functions from the Account Applications service.
- Return to the command line interface of the Cloud9 instance, replace the contents of the statemachine/account-application-workflow.asl.json file with the content below.
{
"StartAt": "Check Name",
"States": {
"Check Name": {
"Type": "Task",
"Parameters": {
"command": "CHECK_NAME",
"data": {
"name.$": "$.application.name"
}
},
"Resource": "${DataCheckingFunctionArn}",
"ResultPath": "$.checks.name",
"Next": "Check Address"
},
"Check Address": {
"Type": "Task",
"Parameters": {
"command": "CHECK_ADDRESS",
"data": {
"address.$": "$.application.address"
}
},
"Resource": "${DataCheckingFunctionArn}",
"ResultPath": "$.checks.address",
"Next": "Review Required?"
},
"Review Required?": {
"Type": "Choice",
"Choices": [
{
"Variable": "$.checks.name.flagged",
"BooleanEquals": true,
"Next": "Pending Review"
},
{
"Variable": "$.checks.address.flagged",
"BooleanEquals": true,
"Next": "Pending Review"
}
],
"Default": "Approve Application"
},
"Pending Review": {
"Type": "Task",
"Resource": "arn:aws:states:::lambda:invoke.waitForTaskToken",
"Parameters": {
"FunctionName": "${FlagApplicationFunctionName}",
"Payload": {
"id.$": "$.application.id",
"flagType": "REVIEW",
"taskToken.$": "$$.Task.Token"
}
},
"ResultPath": "$.review",
"Next": "Review Approved?"
},
"Review Approved?": {
"Type": "Choice",
"Choices": [
{
"Variable": "$.review.decision",
"StringEquals": "APPROVE",
"Next": "Approve Application"
},
{
"Variable": "$.review.decision",
"StringEquals": "REJECT",
"Next": "Reject Application"
}
]
},
"Reject Application": {
"Type": "Task",
"Parameters": {
"id.$": "$.application.id"
},
"Resource": "${RejectApplicationFunctionArn}",
"End": true
},
"Approve Application": {
"Type": "Task",
"Parameters": {
"id.$": "$.application.id"
},
"Resource": "${ApproveApplicationFunctionArn}",
"End": true
}
}
}
- Replace the content of the file template.yaml with the content below.
- Press Ctrl + S to save changes.
AWSTemplateFormatVersion: "2010-09-09"
Transform: AWS::Serverless-2016-10-31
Description: Template for step-functions-workshop
Resources:
ApplicationProcessingStateMachine:
Type: AWS::Serverless::StateMachine
Properties:
DefinitionUri: statemachine/account-application-workflow.asl.json
DefinitionSubstitutions:
DataCheckingFunctionArn: !GetAtt DataCheckingFunction.Arn
FlagApplicationFunctionName: !Ref FlagApplicationFunction
ApproveApplicationFunctionArn: !GetAtt ApproveApplicationFunction.Arn
RejectApplicationFunctionArn: !GetAtt RejectApplicationFunction.Arn
Policies:
- LambdaInvokePolicy:
FunctionName: !Ref DataCheckingFunction
- LambdaInvokePolicy:
FunctionName: !Ref FlagApplicationFunction
- LambdaInvokePolicy:
FunctionName: !Ref ApproveApplicationFunction
- LambdaInvokePolicy:
FunctionName: !Ref RejectApplicationFunction
ApproveApplicationFunction:
Type: AWS::Serverless::Function
Properties:
FunctionName: sfn-workshop-ApproveApplication
CodeUri: functions/account-applications/
Handler: approve.handler
Runtime: nodejs12.x
Environment:
Variables:
APPLICATIONS_TABLE_NAME: !Ref ApplicationsTable
Policies:
- DynamoDBCrudPolicy:
TableName: !Ref ApplicationsTable
DataCheckingFunction:
Type: AWS::Serverless::Function
Properties:
FunctionName: sfn-workshop-DataChecking
CodeUri: functions/data-checking/
Handler: data-checking.handler
Runtime: nodejs12.x
FindApplicationsFunction:
Type: AWS::Serverless::Function
Properties:
FunctionName: sfn-workshop-FindApplications
CodeUri: functions/account-applications/
Handler: find.handler
Runtime: nodejs12.x
Environment:
Variables:
APPLICATIONS_TABLE_NAME: !Ref ApplicationsTable
Policies:
- DynamoDBCrudPolicy:
TableName: !Ref ApplicationsTable
FlagApplicationFunction:
Type: AWS::Serverless::Function
Properties:
FunctionName: sfn-workshop-FlagApplication
CodeUri: functions/account-applications/
Handler: flag.handler
Runtime: nodejs12.x
Environment:
Variables:
APPLICATIONS_TABLE_NAME: !Ref ApplicationsTable
Policies:
- DynamoDBCrudPolicy:
TableName: !Ref ApplicationsTable
RejectApplicationFunction:
Type: AWS::Serverless::Function
Properties:
FunctionName: sfn-workshop-RejectApplication
CodeUri: functions/account-applications/
Handler: reject.handler
Runtime: nodejs12.x
Environment:
Variables:
APPLICATIONS_TABLE_NAME: !Ref ApplicationsTable
Policies:
- DynamoDBCrudPolicy:
TableName: !Ref ApplicationsTable
ReviewApplicationFunction:
Type: AWS::Serverless::Function
Properties:
FunctionName: sfn-workshop-ReviewApplication
CodeUri: functions/account-applications/
Handler: review.handler
Runtime: nodejs12.x
Environment:
Variables:
APPLICATIONS_TABLE_NAME: !Ref ApplicationsTable
Policies:
- DynamoDBCrudPolicy:
TableName: !Ref ApplicationsTable
- Statement:
- Sid: AllowCallbacksToStateMachinePolicy
Effect: "Allow"
Action:
- "states:SendTaskSuccess"
- "states:SendTaskFailure"
Resource: !Ref ApplicationProcessingStateMachine
SubmitApplicationFunction:
Type: AWS::Serverless::Function
Properties:
FunctionName: sfn-workshop-SubmitApplication
CodeUri: functions/account-applications/
Handler: submit.handler
Runtime: nodejs12.x
Environment:
Variables:
APPLICATIONS_TABLE_NAME: !Ref ApplicationsTable
APPLICATION_PROCESSING_STEP_FUNCTION_ARN: !Ref ApplicationProcessingStateMachine
Policies:
- DynamoDBCrudPolicy:
TableName: !Ref ApplicationsTable
- StepFunctionsExecutionPolicy:
StateMachineName: !GetAtt ApplicationProcessingStateMachine.Name
ApplicationsTable:
Type: 'AWS::DynamoDB::Table'
Properties:
TableName: !Sub StepFunctionWorkshop-AccountApplications-${AWS::StackName}
AttributeDefinitions:
-
AttributeName: id
AttributeType: S
-
AttributeName: state
AttributeType: S
KeySchema:
-
AttributeName: id
KeyType: HASH
BillingMode: PAY_PER_REQUEST
GlobalSecondaryIndexes:
-
IndexName: state
KeySchema:
-
AttributeName: state
KeyType: HASH
Projection:
ProjectionType: ALL
Outputs:
SubmitApplicationFunctionArn:
Description: "Submit Application Function ARN"
Value: !GetAtt SubmitApplicationFunction.Arn
FlagApplicationFunctionArn:
Description: "Flag Application Function ARN"
Value: !GetAtt FlagApplicationFunction.Arn
FindApplicationsFunctionArn:
Description: "Find Applications Function ARN"
Value: !GetAtt FindApplicationsFunction.Arn
ApproveApplicationFunctionArn:
Description: "Approve Application Function ARN"
Value: !GetAtt ApproveApplicationFunction.Arn
RejectApplicationFunctionArn:
Description: "Reject Application Function ARN"
Value: !GetAtt RejectApplicationFunction.Arn
DataCheckingFunctionArn:
Description: "Data Checking Function ARN"
Value: !GetAtt DataCheckingFunction.Arn
- Run the command below to execute the build and deploy, and check the deployment is successful before doing the next step:
sam build && sam deploy
Congratulations, you’ve completed creating a basic workflow on the Step Functions state machine. In the next section we’ll learn about what to do when something goes wrong while the state machine is running.
