check-cert-expiration

Queries an SSL/TLS server and reports when its certificate expires.

Installation

npm install --global check-cert-expiration # for the command line utility
npm install --save check-cert-expiration # for the library function

Command Line Interface

The check-cert-expiration script accepts 1 or more URLs as command line arguments and prints the results.

One optional command line argument is supported:

• --days-left N exit with status code 1 if N is greater than or equal to daysLeft. Useful for warning about certificates expiring soon.

Examples

Happy path (return code is 0):

$ check-cert-expiration tomcort.com github.com
host=tomcort.com port=443 valid_to=2018-03-09T10:34:20.000Z daysLeft=89
host=github.com port=443 valid_to=2018-05-17T12:00:00.000Z daysLeft=159

$ check-cert-expiration --days-left 14 tomcort.com
host=tomcort.com port=443 valid_to=2020-05-16T17:38:41.000Z daysLeft=37

Error path (return code is 1):

$ check-cert-expiration does-not-exist.example.com
{ CHECK_CERT_EXPIRATION_COMM: getaddrinfo ENOTFOUND does-not-exist.example.com does-not-exist.example.com:443
    at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:56:26)
  errno: 'ENOTFOUND',
  code: 'ENOTFOUND',
  syscall: 'getaddrinfo',
  hostname: 'does-not-exist.example.com',
  host: 'does-not-exist.example.com',
  port: 443,
  name: 'CHECK_CERT_EXPIRATION_COMM' }

$ check-cert-expiration --days-left 42 tomcort.com
{ CHECK_CERT_EXPIRATION_DAYS_LEFT: daysLeft is less than or equal to the --days-left command line option
    at process.argv.forEach (/Users/thomasc/repos/check-cert-expiration/bin/check-cert-expiration:27:25)
    at process._tickCallback (internal/process/next_tick.js:68:7)
name: 'CHECK_CERT_EXPIRATION_DAYS_LEFT',
host: 'tomcort.com',
port: 443,
valid_to: '2020-05-16T17:38:41.000Z',
daysLeft: 37,
warnDaysLeft: 42 }

API

checkCertExpiration(targetUrl)

Parameters:

• targetUrl - a server URL (e.g. https://www.tomcort.com/) or hostname (e.g. tomcort.com).

Return Value:

• result object with the following properties:
  • host - hostname of the host checked.
  • port - TCP port number of the host checked,
  • valid_to - ISO8601 timestamp string.
  • daysLeft - how many days left until the certificate expires.

Errors:

Errors with the following values of err.name may occur:

• CHECK_CERT_EXPIRATION_URL_PARSE - when a URL parse error is encountered.
• CHECK_CERT_EXPIRATION_BAD_PROTOCOL - when the protocol portion of the URL is not https:
• CHECK_CERT_EXPIRATION_COMM - when there is some type of communications error.

Examples

'use strict';

const checkCertExpiration = require('check-cert-expiration');

(async function () {
    try {
        const { daysLeft, host, port } = await checkCertExpiration('tomcort.com');
        console.log(`${daysLeft} days until the certificate expires for ${host}:${port}`);
        process.exit(0);
    } catch (err) {
        console.error(`${err.name}:${err.message}`);
        process.exit(1);
    }
})();

Testing

npm test

License

See LICENSE.md