https://github.com/eoinsha/step-function-api-example

Example Express Step Function behind a REST API in API Gateway
https://github.com/eoinsha/step-function-api-example

Last synced: 11 days ago
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Example Express Step Function behind a REST API in API Gateway

• Host: GitHub
• URL: https://github.com/eoinsha/step-function-api-example
• Owner: eoinsha
• Created: 2024-03-12T13:39:32.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2024-03-12T13:43:19.000Z (over 1 year ago)
• Last Synced: 2025-04-09T23:48:18.980Z (3 months ago)
• Language: TypeScript
• Size: 162 KB
• Stars: 2
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Step Function Express API Example

This is a simple Step Function (EXPRESS) implementation of an AWS API Gateway REST API.

It uses CDK to construct a sample state machine that is invoked by an API Gateway Proxy Integration.

## Step Function Design

The state machine invokes an HTTPS endpoint using an [HTTP Task](https://docs.aws.amazon.com/step-functions/latest/dg/connect-third-party-apis.html) defined by an EventBridge HTTP Connection.

A choice state allows the HTTP invocation to be skipped if the `skip=true` query string is provided in the URL.

![Step Function design include a Pass State, a "Skip API" Choice State and an HTTP Endpoint API Invocation](step-function-definition.png)

## Deployment

```sh

npm install

cdk deploy

```

The API Gateway HTTPS endpoint is printed to the screen on successful deployment.

## Evaluating

X-Ray tracing is enabled for the API deployment and the Step Function, allowing you to see errors and performance metrics.

Execute the API as follows (using cURL):

```sh

curl -v https://.execute-api.eu-west-1.amazonaws.com/prod

```

To skip the API invocation and run the simple `Pass` and `Choice` states of the step function, add the `skip=true` query parameter:

```sh

curl -v "https://.execute-api.eu-west-1.amazonaws.com/prod?skip=true"

```

With the HTTP invocation step, this sample shows 404ms end-to-end with 369ms of that for the HTTP invocation.

![AWS X-Ray trace showing the timelines of segments including HTTP invocation](trace-with-api.png)

Skipping the HTTP invocation step, the following sample shows 98ms end-to-end, with 13ms for the State Machine execution. The rest of the time appears to be in the Step Function service orchestration.

![AWS X-Ray trace showing the timelines of segments when HTTP invocation is skipped](trace-without-api.png)

## Cleaning up

```sh

cdk destroy

```