10 KiB


🔐 Free SSL, Free Wildcard SSL, and Fully Automated HTTPS for Node.js and Browsers, issued by Let's Encrypt v2 via ACME

Greenlock™ is the easiest way to integrate Let's Encrypt into your projects, products, and infrastructure.

  • Wildcard Certificates
  • IoT Environments
  • Enterprise and On-Prem
  • Private Networks
  • Localhost Development
  • Web Hosting Providers
  • Commercial support

We've built it simple enough for Hobbyists, and robust enough for the Enterprise.

JavaScript Library

Greenlock API (shared among JS implementations)


// Creates an instance of greenlock with certain default values

var gl = Greenlock.create({
	// Staging for testing environments
	staging: true,

	// This should be the contact who receives critical bug and security notifications
	// Optionally, you may receive other (very few) updates, such as important new features
	maintainerEmail: ''
Parameter Description
maintainerEmail the developer contact for critical bug and security notifications
packageAgent if you publish your package for others to use, require('./package.json').name here

Add Approved Domains

	// The "Let's Encrypt Subscriber" (often the same as the maintainer)
	// NOT the end customer (except where that is also the maintainer)
	subscriberEmail: '',
	agreeToTerms: true
Parameter Description
agreeToTerms (default: false) either 'true' or a function that presents the Terms of Service and returns it once accepted
challenges['http-01'] provide an http-01 challenge module
challenges['dns-01'] provide a dns-01 challenge module
challenges['tls-alpn-01'] provide a tls-alpn-01 challenge module
challenges[type].module the name of your challenge module
challenges[type].xxxx module-specific options
servername the default servername to use for non-sni requests (many IoT clients)
subscriberEmail the contact who agrees to the Let's Encrypt Subscriber Agreement and the Greenlock Terms of Service
this contact receives renewal failure notifications
store override the default storage module
store.module the name of your storage module
store.xxxx options specific to your storage module
	subject: '',
	altnames: ['', '', '']
Parameter Description
subject the first domain on, and identifier of the certificate
altnames first domain, plus additional domains
note: the order should always be the same
subscriberEmail if different from the default (i.e. multi-tenant, whitelabel)
agreeToTerms if subscriber is different from the default
challenges (same as main config) use if this site needs to use non-default http-01 or dns-01 validation

Issue Certificates

return greenlock.get({ servername }).then(function(site) {
	if (!site) {
		console.log(servername + ' was not found in any site config');

	var privkey = site.pems.privkey;
	var fullchain = site.pems.cert + '\n' + site.pems.chain + '\n';
Parameter Description
servername the first domain on, and identifier of the certificate

Renew Certificates

This will renew only domains that have reached their renewAt or are within the befault renewOffset.

return greenlock.renew({}).then(function(results) {
	results.forEach(function(site) {
		if (site.error) {
			console.error(site.subject, site.error);
		console.log('Renewed certificate for', site.subject, site.altnames);
Parameter Type Description
(optional) ALL parameters are optional, but some should be paired
force bool force silly options, such as tiny durations
issuedBefore ms Check domains issued before the given date in milliseconds
expiresBefore ms Check domains that expire before the given date in milliseconds
renewBefore ms Check domains that are scheduled to renew before the given date in milliseconds

Force a certificate to renew

greenlock.update({ subject, renewAt: 0 }).then(function() {
	return greenlock.renew({});

Note: only previous approved domains (via gl.add()) may be renewed

Note: this will NOT throw an error. It will return an array of certifates or errors.



npm install --save @root/greenlock
npm install --save greenlock-manager-fs
npm install --save greenlock-store-fs
npm install --save acme-http-01-standalone

HTTP-01 & DNS-01 Integrations

For Public Web Servers running on a VPS, the default HTTP-01 challenge plugin will work just fine for most people.

However, for

  • Wildcard Certificates
  • IoT Environments
  • Enterprise On-Prem
  • Private Networks

Greenlock provides an easy way to integrate Let's Encrypt with your existing services through a variety of DNS-01 infrastructure

Why Typically file propagation is faster and more reliably than DNS propagation. Therefore, http-01 will be preferred to dns-01 except when wildcards or private domains are in use.

http-01 will only be supplied as a defaut if no other challenge is provided.

You can use ACME (Let's Encrypt) with