SSL/TLSの証明書の有効期間をSlackに通知するツール

index.js

'use strict';

const { IncomingWebhook } = require('@slack/client');
const https = require('https');
const moment = require('moment');

async function sendSlackNotification(message) {
  const url = process.env.SLACK_INCOMING_WEBHOOK_URL;
  const slackIncomingWebhook = new IncomingWebhook(url);
  return await slackIncomingWebhook.send({
    text: message,
  });
}

async function getCertificateRemainingInDays(hostname, port) {
  return new Promise((resolve, reject) => {
    const req = https.request({
      hostname: hostname,
      port: port || 443,
    }, (res) => {
      const certificate = res.connection.getPeerCertificate();
      const expirationDate = moment(certificate.valid_to, 'MMM D HH:mm:ss YYYY GMT');
      const remainingInDays = expirationDate.diff(moment(), 'days');
      resolve(remainingInDays);
    }).on('error', (err) => {
      console.error(err.stack);
      reject(err);
    });
    req.end();
  });
}

(async () => {
  const targets = [
    { hostname: 'iruca.co', port: 443 },
    { hostname: 'mimemo.io', port: 443 },
  ];
  let message = '[CERTIFICATE INFORMATION]\n';
  for (const target of targets) {
    let remainingInDays = await getCertificateRemainingInDays(target.hostname, target.port);
    remainingInDays += (remainingInDays > 1) ? ' days' : ' day';
    message += `${target.hostname}: remaining ${remainingInDays}\n`;
  }
  await sendSlackNotification(message);
})();

package.json

{
  "name": "check-certificate-expiration",
  "version": "1.0.0",
  "dependencies": {
    "@slack/client": "^5.0.2",
    "moment": "^2.24.0"
  }
}