An example of a typed state machine lambda handler with middy and powertools

example-state-machine-handler.ts

import { Logger } from '@aws-lambda-powertools/logger';
import { injectLambdaContext } from '@aws-lambda-powertools/logger/middleware';
import { Metrics } from '@aws-lambda-powertools/metrics';
import { logMetrics } from '@aws-lambda-powertools/metrics/middleware';
import { Tracer } from '@aws-lambda-powertools/tracer';
import { captureLambdaHandler } from '@aws-lambda-powertools/tracer/middleware';
import middy from '@middy/core';
import { Handler } from 'aws-lambda';

interface StateMachineEvent {
  someProperty: string;
  anotherProperty: number;
}

interface CustomContext {
  // add properties specific to your context
}

interface CustomResponse {
  something: string;
  secondThing: number;
}

const tracer = new Tracer();
const metrics = new Metrics();
const logger = new Logger();

const myHandler: Handler<StateMachineEvent, CustomResponse> = async (
  event: StateMachineEvent,
  context: CustomContext
): Promise<CustomResponse> => {
  // TODO - code goes here for the handler

  const { someProperty, anotherProperty } = event;

  logger.info(
    `someProperty: ${someProperty}, anotherProperty: ${anotherProperty}`
  );

  return {
    something: 'something',
    secondThing: 1,
  };
};

export const handler = middy(myHandler)
  .use(injectLambdaContext(logger))
  .use(captureLambdaHandler(tracer))
  .use(logMetrics(metrics));