Serverless Framework: How to properly define parallel branches? - serverless-framework

Question

I am trying to translate the following Amazon Step Functions definition from JSON to Serverless YML.
Here is the JSON version (which is working fine):
{
"Comment": "Parallel Evaluation of multiple Book Pricing atributes.",
"StartAt": "VerifyBookPricingAttributes",
"States": {
"VerifyBookPricingAttributes": {
"Type": "Parallel",
"Next": "ReturnCombinedData",
"Branches": [{
"StartAt": "ConfirmBookAvailability",
"States": {
"ConfirmBookAvailability": {
"Type": "Task",
"Comment": "This state will query DynamoDB table representing RS catalog. If the Book is found - availability will be confirmed",
"Resource": "arn:aws:lambda:us-east-1:000000000000:function:ConfirmBookAvailability",
"ResultPath": "$.BookAvailability",
"End": true
}
}
},
{
"StartAt": "ConfirmBookPriceIsValid",
"States": {
"ConfirmBookPriceIsValid": {
"Type": "Task",
"Comment": "This state will query DynamoDB table representing Book Prices. If the input BookPrice matches the Dynamo valid - the pricing will be confirmed",
"Resource": "arn:aws:lambda:us-east-1:000000000000:function:ConfirmBookPriceIsValid",
"ResultPath": "$.IsBookPriceValid",
"End": true
}
}
}
]
},
"ReturnCombinedData": {
"Type": "Pass",
"Parameters": {
"comment": "Combining the result",
"CombinedDetails": {
"BookAvailability.$": "$[0].BookAvailability",
"IsBookPriceValid.$": "$[1].IsBookPriceValid"
}
},
"End": true
}
}
}
The things to note are: Parallel type with Branches
I've started translating this into Serverless YML:
stepFunctions:
stateMachines:
Process-BookPricingCreated-StateMachine:
name: myStateMachine
definition:
StartAt: VerifyBookPricingAttributes
States:
VerifyBookPricingAttributes:
Type: Parallel
Next: ReturnCombinedData
Branches:
StartAt: ConfirmBookAvailability
States:
ConfirmBookAvailability:
Type: Task
Resource: arn:aws:lambda:us-east-1:000000000000:function:ConfirmBookAvailability
ResultPath": $.BookAvailability
End: true
StartAt: ConfirmBookPriceIsValid
States:
ConfirmBookPriceIsValid:
Type: Task
Resource: arn:aws:lambda:us-east-1:000000000000:function:ConfirmBookPriceIsValid
ResultPath: $.IsBookPriceValid
End: true
I am running into an issue where Serverless complains about having StartAt and State as duplicate keys (since those are parallel branches.
How do I properly deal with the Parallel Branches using Serverless Framework?

Answer 1

Branches should be a list and looks like you have an extra " in your first ResultPath
stepFunctions:
stateMachines:
Process-BookPricingCreated-StateMachine:
name: myStateMachine
definition:
StartAt: VerifyBookPricingAttributes
States:
VerifyBookPricingAttributes:
Type: Parallel
Next: ReturnCombinedData
Branches:
- StartAt: ConfirmBookAvailability
States:
ConfirmBookAvailability:
Type: Task
Resource: arn:aws:lambda:us-east-1:000000000000:function:ConfirmBookAvailability
ResultPath: $.BookAvailability
End: true
- StartAt: ConfirmBookPriceIsValid
States:
ConfirmBookPriceIsValid:
Type: Task
Resource: arn:aws:lambda:us-east-1:000000000000:function:ConfirmBookPriceIsValid
ResultPath: $.IsBookPriceValid
End: true