app.js

const { App, AwsLambdaReceiver } = require('@slack/bolt');

// Initialize your custom receiver
const awsLambdaReceiver = new AwsLambdaReceiver({
  signingSecret: process.env.SLACK_SIGNING_SECRET,
});

// Initializes your app with your bot token and the AWS Lambda ready receiver
const app = new App({
  token: process.env.SLACK_BOT_TOKEN,
  receiver: awsLambdaReceiver,

  // When using the AwsLambdaReceiver, processBeforeResponse can be omitted.
  // If you use other Receivers, such as ExpressReceiver for OAuth flow support
  // then processBeforeResponse: true is required. This option will defer sending back
  // the acknowledgement until after your handler has run to ensure your function
  // isn't terminated early by responding to the HTTP request that triggered it.

  // processBeforeResponse: true
});

// Listens to incoming messages that contain "hello"
app.message('hello', async ({ message, say }) => {
  // say() sends a message to the channel where the event was triggered
  await say({
    blocks: [
      {
        type: 'section',
        text: {
          type: 'mrkdwn',
          text: `Hey there <@${message.user}>!`,
        },
        accessory: {
          type: 'button',
          text: {
            type: 'plain_text',
            text: 'Click Me',
          },
          action_id: 'button_click',
        },
      },
    ],
    text: `Hey there <@${message.user}>!`,
  });
});

// Listens for an action from a button click
app.action('button_click', async ({ body, ack, say }) => {
  await ack();

  await say(`<@${body.user.id}> clicked the button`);
});

// Listens to incoming messages that contain "goodbye"
app.message('goodbye', async ({ message, say }) => {
  // say() sends a message to the channel where the event was triggered
  await say(`See ya later, <@${message.user}> :wave:`);
});

// Handle the Lambda function event
module.exports.handler = async (event, context, callback) => {
  const handler = await awsLambdaReceiver.start();
  return handler(event, context, callback);
};