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greenlock (node-letsencrypt)

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Automatic Let's Encrypt (ACME) HTTPS / TLS / SSL Certificates for node.js

Free SSL with 90-day HTTPS / TLS Certificates

Are these the droids you're looking for?

This is a low-level library for implementing ACME / LetsEncrypt Clients, CLIs, system tools, and abstracting storage backends (file vs db, etc).

For express, raw https or spdy, or restify (same as raw https) see letsencrypt-express and letsencrypt-cluster.

For hapi see letsencrypt-hapi.

For koa or rill see letsencrypt-koa.

For bash, fish, zsh, cmd.exe, PowerShell see letsencrypt-cli.


letsencrypt requires at least two plugins: one for managing certificate storage and the other for handling ACME challenges.

The default storage plugin is le-store-certbot and the default challenge is le-challenge-fs.

npm install --save letsencrypt@2.x

npm install --save le-store-certbot@2.x   # default plugin for accounts, certificates, and keypairs
npm install --save le-challenge-fs@2.x    # default plugin for challenge handlers
npm install --save le-acme-core@2.x       # default plugin for ACME spec
npm install --save le-sni-auto@2.x        # default plugin for SNICallback

Important: Use node v4.5+ or v6.x, node <= v4.4 has a known bug in the Buffer implementation.


It's very simple and easy to use, but also very complete and easy to extend and customize.

Overly Simplified Example

Against my better judgement I'm providing a terribly oversimplified example of how to use this library:

var le = require('letsencrypt').create({ server: 'staging' });

var opts = {
  domains: ['example.com'], email: 'user@email.com', agreeTos: true

le.register(opts).then(function (certs) {
  // privkey, cert, chain, expiresAt, issuedAt, subject, altnames
}, function (err) {

You also need some sort of server to handle the acme challenge:

var app = express();
app.use('/', le.middleware());

Note: The webrootPath string is a template. Any occurance of :hostname will be replaced with the domain for which we are requested certificates.

Useful Example

The configuration consists of 3 components:

  • Storage Backend (search npm for projects starting with 'le-store-')
  • ACME Challenge Handlers (search npm for projects starting with 'le-challenge-')
  • Letsencryt Config (this is all you)
'use strict';

var LE = require('letsencrypt');
var le;

// Storage Backend
var leStore = require('le-store-certbot').create({
  configDir: '~/letsencrypt/etc'                          // or /etc/letsencrypt or wherever
, debug: false

// ACME Challenge Handlers
var leChallenge = require('le-challenge-fs').create({
  webrootPath: '~/letsencrypt/var/'                       // or template string such as
, debug: false                                            // '/srv/www/:hostname/.well-known/acme-challenge'

function leAgree(opts, agreeCb) {
  // opts = { email, domains, tosUrl }
  agreeCb(null, opts.tosUrl);

le = LE.create({
  server: LE.stagingServerUrl                             // or LE.productionServerUrl
, store: leStore                                          // handles saving of config, accounts, and certificates
, challenges: { 'http-01': leChallenge }                  // handles /.well-known/acme-challege keys and tokens
, challengeType: 'http-01'                                // default to this challenge type
, agreeToTerms: leAgree                                   // hook to allow user to view and accept LE TOS
//, sni: require('le-sni-auto').create({})                // handles sni callback
, debug: false
//, log: function (debug) {console.log.apply(console, args);} // handles debug outputs

// If using express you should use the middleware
// app.use('/', le.middleware());
// Otherwise you should see the test file for usage of this:
// le.challenges['http-01'].get(opts.domain, key, val, done)

// Check in-memory cache of certificates for the named domain
le.check({ domains: [ 'example.com' ] }).then(function (results) {
  if (results) {
    // we already have certificates

  // Register Certificate manually

    domains: ['example.com']                                // CHANGE TO YOUR DOMAIN (list for SANS)
  , email: 'user@email.com'                                 // CHANGE TO YOUR EMAIL
  , agreeTos: ''                                            // set to tosUrl string (or true) to pre-approve (and skip agreeToTerms)
  , rsaKeySize: 2048                                        // 2048 or higher
  , challengeType: 'http-01'                                // http-01, tls-sni-01, or dns-01

  }).then(function (results) {


  }, function (err) {

    // Note: you must either use le.middleware() with express,
    // manually use le.challenges['http-01'].get(opts, domain, key, val, done)
    // or have a webserver running and responding
    // to /.well-known/acme-challenge at `webrootPath`
    console.error('[Error]: node-letsencrypt/examples/standalone');



Here's what results looks like:

{ privkey: ''     // PEM encoded private key
, cert: ''        // PEM encoded cert
, chain: ''       // PEM encoded intermediate cert
, issuedAt: 0     // notBefore date (in ms) parsed from cert
, expiresAt: 0    // notAfter date (in ms) parsed from cert
, subject: ''     // example.com
, altnames: []    // example.com,www.example.com


The full end-user API is exposed in the example above and includes all relevant options.


Helper Functions

We do expose a few helper functions:

  • LE.validDomain(hostname) // returns '' or the hostname string if it's a valid ascii or punycode domain name

TODO fetch domain tld list

Template Strings

The following variables will be tempalted in any strings passed to the options object:

  • ~/ replaced with os.homedir() i.e. /Users/aj
  • :hostname replaced with the first domain in the list i.e. example.com

Developer API

If you are developing an le-store-* or le-challenge-* plugin you need to be aware of additional internal API expectations.


Use v2.0.0 as your initial version - NOT v0.1.0 and NOT v1.0.0 and NOT v3.0.0. This is to indicate that your module is compatible with v2.x of node-letsencrypt.

Since the public API for your module is defined by node-letsencrypt the major version should be kept in sync.

store implementation

See https://github.com/Daplie/le-store-SPEC

  • getOptions()
  • accounts.
    • checkKeypair(opts, cb)
    • check(opts, cb)
    • setKeypair(opts, keypair, cb)
    • set(opts, reg, cb)
  • certificates.
    • checkKeypair(opts, cb)
    • check(opts, cb)
    • setKeypair(opts, keypair, cb)
    • set(opts, reg, cb)

challenge implementation

See https://github.com/Daplie/le-challenge-fs

  • .set(opts, domain, key, value, cb); // opts will be saved with domain/key
  • .get(opts, domain, key, cb); // opts will be retrieved by domain/key
  • .remove(opts, domain, key, cb); // opts will be retrieved by domain/key

Change History

  • v2.0.2 - Aug 9th 2016 update readme
  • v2.0.1 - Aug 9th 2016
    • major refactor
    • simplified API
    • modular plugins
    • knock out bugs
  • v1.5.0 now using letiny-core v2.0.0 and rsa-compat
  • v1.4.x I can't remember... but it's better!
  • v1.1.0 Added letiny-core, removed node-letsencrypt-python
  • v1.0.2 Works with node-letsencrypt-python
  • v1.0.0 Thar be dragons


Dual-licensed MIT and Apache-2.0