SSL Certificate Monitoring Made Simple — Node.js One-Liner

#security #node #webdev #devops

SSL certificate expiry is one of the most common causes of website outages. Here's how to check it in Node.js:

import https from "https";

const req = https.request({hostname: "google.com", port: 443, method: "HEAD"}, res => {
  const cert = res.socket.getPeerCertificate();
  const validTo = new Date(cert.valid_to);
  const daysLeft = Math.floor((validTo - new Date()) / 86400000);
  console.log(`Issuer: ${cert.issuer.O}`);
  console.log(`Expires: ${cert.valid_to}`);
  console.log(`Days left: ${daysLeft}`);
  console.log(`Status: ${daysLeft < 30 ? "WARNING" : "OK"}`);
});
req.end();