AWS Step Functions task token

Use Step Functions with task tokens to pause execution, send a message to an SQS queue, and resume after processing.

// Create a queue the state machine will send messages to
const queue = new sst.aws.Queue("MyQueue");

// Define all the states of the state machine
const sendMessage = sst.aws.StepFunctions.sqsSendMessage({
  name: "SendMessage",
  integration: "token",
  queue,
  messageBody: {
    // Task token passed in the message body
    MyTaskToken: "{% $states.context.Task.Token %}",
  },
});
const success = sst.aws.StepFunctions.succeed({ name: "Succeed" });

// Create the state machine
const stepFunction = new sst.aws.StepFunctions("MyStateMachine", {
  definition: sendMessage.next(success),
});

// Create a function that will receive messages from the queue
queue.subscribe({
  handler: "index.handler",
  // Linking the state machine to grant permissions to call `SendTaskSuccess`
  link: [stepFunction],
});

import { SQSEvent } from "aws-lambda";
import { SFNClient, SendTaskSuccessCommand } from "@aws-sdk/client-sfn";

const sfn = new SFNClient();

export async function handler(e: SQSEvent) {
  // Parse the task token
  const { body } = e.Records[0];
  const { MyTaskToken } = JSON.parse(body);

  // Do some work
  await new Promise((resolve) => setTimeout(resolve, 1000));

  // Call `SendTaskSuccess` to mark the task done
  await sfn.send(
    new SendTaskSuccessCommand({
      taskToken: MyTaskToken,
      output: JSON.stringify({ result: "foo" }),
    })
  );

  return "ok";
}

View the full example.