Serverless Step Functions: no more leaky abstractions
Tags: aws, lambda, stepfunctions, serverless
Published: 2019-07-31 21:59:20

---
title: Serverless Step Functions: no more leaky abstractions
published: true
tags: AWS,Lambda,StepFunctions,Serverless
canonical_url: https://theburningmonk.com/2019/07/serverless-step-functions-no-more-leaky-abstractions/
---

I have some exciting news to share with you about the [Serverless Step Functions](https://github.com/horike37/serverless-step-functions) plugin.

![](https://theburningmonk.com/wp-content/uploads/2019/07/img_5d41fd661314c.png)

One of the main pain points of using the plugin was that you needed to use fully-formed ARNs. We addressed this in [v1.18.0](https://github.com/horike37/serverless-step-functions/releases/tag/v1.18.0) by supporting CloudFormation intrinsic functions `Fn:GetAtt` and `Ref`. This makes it possible for you to reference a local function instead.

```
functions: hello-world: handler: hello-world.handlerstepFunctions: stateMachines: myStateMachine: definition: StartAt: HelloWorld States: HelloWorld: Type: Task Resource: Fn::GetAtt: [HelloDashworldLambdaFunction, Arn] End: true
```

But this is still a leaky abstraction – you have to know how the [Serverless framework](https://serverless.com/framework/) converts local function names into CloudFormation logical IDs.

Newcomers would often get confused here.

> “How did you get the logical ID _`HelloDashworldLambdaFunction`_ from `hello-world`?”

I can hardly blame them for not knowing. This is an implementation detail in the Serverless framework, one that you shouldn’t have to care about!

Which is why I’m really happy to tell you that, as of [v2.2.0](https://github.com/horike37/serverless-step-functions/releases/tag/v2.2.0) you can reference local functions using their local names in the state machine definition.

{% gist https://gist.github.com/theburningmonk/de87c55aec0974751d5b05a7fbdb1644 %}

In the above example, when we reference the local function `hello-world` we no longer need to use its CloudFormation logical ID `HelloDashworldLambdaFunction`.

As you can see from the example, it applies when you use either `Ref` or `Fn::GetAtt` functions in a `Task` state. And it applies to all 3 ways of invoking a Lambda function from a `Task` state.

 ![](https://theburningmonk.com/wp-content/uploads/2019/03/img_5c8ca195210d5.png)

Hi, my name is **Yan Cui**. I’m an **[AWS Serverless Hero](https://aws.amazon.com/developer/community/heroes/yan-cui/)** and the author of [**Production-Ready Serverless**](https://bit.ly/production-ready-serverless). I have run production workload at scale in AWS for nearly 10 years and I have been an architect or principal engineer with a variety of industries ranging from banking, e-commerce, sports streaming to mobile gaming. I currently work as an independent consultant focused on AWS and serverless.

You can contact me via [Email](mailto:theburningmonk.com), [Twitter](https://twitter.com/theburningmonk) and [LinkedIn](https://www.linkedin.com/in/theburningmonk/).

[Hire me.](https://theburningmonk.com/hire-me)

The post [Serverless Step Functions: no more leaky abstractions](https://theburningmonk.com/2019/07/serverless-step-functions-no-more-leaky-abstractions/) appeared first on [theburningmonk.com](https://theburningmonk.com).

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