sendMessageToSlack.js

const url = require('url');
const https = require('https');

const slack_url  = url.parse(process.env.SLACK_URL);
const channel    = process.env.CHANNEL;
const username   = process.env.USERNAME;
const icon_emoji = process.env.ICON_EMOJI;
const messages   = {
  SINGLE : process.env.SINGLE_CLICK_MESSAGE,
  DOUBLE : process.env.DOUBLE_CLICK_MESSAGE,
  LONG   : process.env.LONG_CLICK_MESSAGE,
};

exports.handler = async (event) => {
  return new Promise((resolve, reject) => {
    const clickType = event['deviceEvent']['buttonClicked']['clickType'];
    const text = messages[clickType];

    const payload = JSON.stringify({ text, channel, username, icon_emoji });
    const options = {
      host: slack_url.hostname,
      path: slack_url.pathname,
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Content-Length': payload.length,
      },
    };

    const req = https.request(options, () => resolve('message sent'));
    req.on('error', (error) => reject(`error: ${error.message}`));

    req.write(payload);
    req.end();
  });
};