531 lines
16 KiB
Markdown
531 lines
16 KiB
Markdown
letsencrypt
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===========
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Automatic [Let's Encrypt](https://letsencrypt.org) HTTPS Certificates for node.js
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* Automatic HTTPS with ExpressJS
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* Automatic live renewal (in-process)
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* On-the-fly HTTPS certificates for Dynamic DNS (in-process, no server restart)
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* Works with node cluster out of the box
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* usable via commandline as well
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* Free SSL (HTTPS Certificates for TLS)
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* [90-day certificates](https://letsencrypt.org/2015/11/09/why-90-days.html)
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**See Also**
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* See the node-letsencrypt [Examples](https://github.com/Daplie/node-letsencrypt/tree/master/examples)
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* [Let's Encrypt in (exactly) 90 seconds with Caddy](https://daplie.com/articles/lets-encrypt-in-literally-90-seconds/)
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* [lego](https://github.com/xenolf/lego): Let's Encrypt for golang
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Install
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=======
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```bash
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npm install --save letsencrypt
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```
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Right now this uses [`letsencrypt-python`](https://github.com/Daplie/node-letsencrypt-python),
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but it's built to be able to use a node-only javascript version (in progress).
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```bash
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# install the python client (takes 2 minutes normally, 20 on a raspberry pi)
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git clone https://github.com/letsencrypt/letsencrypt
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pushd letsencrypt
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./letsencrypt-auto
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```
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**moving towards a python-free version**
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There are a few partially written javascript implementation, but they use `forge` instead of using node's native `crypto` and `ursa` - so their performance is outright horrific (especially on Raspberry Pi et al). For the moment it's faster to use the wrapped python version.
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Once the `forge` crud is gutted away it should slide right in without a problem. Ping [@coolaj86](https://coolaj86.com) if you'd like to help.
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Usage
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=====
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Here's a simple snippet:
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```javascript
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var config = require('./examples/config-minimal');
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config.le.webrootPath = __dirname + '/tests/acme-challenge';
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var le = require('letsencrypt').create(config.backend, config.le);
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le.register({
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agreeTos: true
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, domains: ['example.com'] // CHANGE TO YOUR DOMAIN
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, email: 'user@email.com' // CHANGE TO YOUR EMAIL
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}, function (err) {
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if (err) {
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console.error('[Error]: node-letsencrypt/examples/standalone');
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console.error(err.stack);
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} else {
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console.log('success');
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}
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plainServer.close();
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tlsServer.close();
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});
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// IMPORTANT
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// you also need BOTH an http AND https server that serve directly
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// from webrootPath, which might as well be a special folder reserved
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// only for acme/letsencrypt challenges
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//
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// app.use('/', express.static(config.le.webrootPath))
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```
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**However**, due to the nature of what this library does, it has a few more "moving parts"
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than what makes sense to show in a minimal snippet.
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Examples
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========
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### One-Time Registration
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Register a 90-day certificate manually, on a whim
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#### Snippets
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[`commandline-minimal`](https://github.com/Daplie/node-letsencrypt/blob/master/examples/commandline-minimal.js):
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**Part 1: the Let's Encrypt client**:
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```javascript
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'use strict';
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var LE = require('letsencrypt');
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var config = require('./config-minimal');
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// Note: you should make this special dir in your product and leave it empty
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config.le.webrootPath = __dirname + '/../tests/acme-challenge';
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config.le.server = LE.stagingServer;
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//
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// Manual Registration
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//
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var le = LE.create(config.backend, config.le);
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le.register({
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agreeTos: true
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, domains: ['example.com'] // CHANGE TO YOUR DOMAIN
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, email: 'user@email.com' // CHANGE TO YOUR EMAIL
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}, function (err) {
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if (err) {
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console.error('[Error]: node-letsencrypt/examples/standalone');
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console.error(err.stack);
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} else {
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console.log('success');
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}
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plainServer.close();
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tlsServer.close();
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});
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```
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**Part 2: Express Web Server**:
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```javascript
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//
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// Express App
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//
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var app = require('express')();
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app.use('/', le.middleware());
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//
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// HTTP & HTTPS servers
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// (required for domain validation)
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//
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var plainServer = require('http').createServer(app).listen(config.plainPort, function () {
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console.log('Listening http', this.address());
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});
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var tlsServer = require('https').createServer({
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key: config.tlsKey
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, cert: config.tlsCert
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, SNICallback: le.sniCallback
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}, app).listen(config.tlsPort, function () {
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console.log('Listening http', this.address());
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});
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```
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#### Runnable Demo
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* [commandline (standalone with "webroot")](https://github.com/Daplie/node-letsencrypt/blob/master/examples/commandline.js)
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```bash
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# manual standalone registration via commandline
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# (runs against testing server on tls port 5001)
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node examples/commandline.js example.com,www.example.com user@example.net agree
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```
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### Express
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Fully Automatic HTTPS with ExpressJS using Free SSL certificates from Let's Encrypt
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#### Snippets
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* [Minimal ExpressJS Example](https://github.com/Daplie/node-letsencrypt/blob/master/examples/express-minimal.js)
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```javascript
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'use strict';
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var LE = require('letsencrypt');
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var config = require('./config-minimal');
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// Note: you should make this special dir in your product and leave it empty
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config.le.webrootPath = __dirname + '/../tests/acme-challenge';
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config.le.server = LE.stagingServer;
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//
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// Automatically Register / Renew Domains
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//
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var le = LE.create(config.backend, config.le, {
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sniRegisterCallback: function (args, expiredCert, cb) {
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// Security: check that this is actually a subdomain we allow
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// (otherwise an attacker can cause you to rate limit against the LE server)
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var hostname = args.domains[0];
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if (!/\.example\.com$/.test(hostname)) {
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console.error("bad domain '" + hostname + "', not a subdomain of example.com");
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cb(nul, null);
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}
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// agree to the LE TOS for this domain
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args.agreeTos = true;
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args.email = 'user@example.com';
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// use the cert even though it's expired
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if (expiredCert) {
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cb(null, expiredCert);
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cb = function () { /*ignore*/ };
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}
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// register / renew the certificate in the background
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le.register(args, cb);
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}
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});
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//
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// Express App
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//
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var app = require('express')();
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app.use('/', le.middleware());
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//
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// HTTP & HTTPS servers
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//
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require('http').createServer(app).listen(config.plainPort, function () {
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console.log('Listening http', this.address());
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});
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require('https').createServer({
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key: config.tlsKey
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, cert: config.tlsCert
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, SNICallback: le.sniCallback
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}, app).listen(config.tlsPort, function () {
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console.log('Listening http', this.address());
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});
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```
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#### Runnable Example
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* [Full ExpressJS Example](https://github.com/Daplie/node-letsencrypt/blob/master/examples/express.js)
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```bash
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# clear out the certificates
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rm -rf tests/letsencrypt.*
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# automatic registration and renewal (certs install as you visit the site for the first time)
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# (runs against testing server on tls port 5001)
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node examples/express.js example.com,www.example.com user@example.net agree
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```
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```bash
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# this will take a moment because it won't respond to the tls sni header until it gets the certs
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curl https://example.com/
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```
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### non-root
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If you want to run this as non-root, you can.
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You just have to set node to be allowed to use root ports
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```
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# node
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sudo setcap cap_net_bind_service=+ep /usr/local/bin/node
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```
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and then make sure to set all of of the following to a directory that your user is permitted to write to
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* `webrootPath`
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* `configDir`
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* `workDir` (python backend only)
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* `logsDir` (python backend only)
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API
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===
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```javascript
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LetsEncrypt.create(backend, bkDefaults, handlers) // wraps a given "backend" (the python client)
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LetsEncrypt.stagingServer // string of staging server for testing
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le.middleware() // middleware for serving webrootPath to /.well-known/acme-challenge
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le.sniCallback(hostname, function (err, tlsContext) {}) // uses fetch (below) and formats for https.SNICallback
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le.register({ domains, email, agreeTos, ... }, cb) // registers or renews certs for a domain
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le.fetch({domains, email, agreeTos, ... }, cb) // fetches certs from in-memory cache, occasionally refreshes from disk
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le.validate(domains, cb) // do some sanity checks before attempting to register
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le.registrationFailureCallback(err, args, certInfo, cb) // called when registration fails (not implemented yet)
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```
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### `LetsEncrypt.create(backend, bkDefaults, handlers)`
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#### backend
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Currently only `letsencrypt-python` is supported, but we plan to work on
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native javascript support in February or so (when ECDSA keys are available).
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If you'd like to help with that, see **how to write a backend** below and also
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look at the wrapper `backend-python.js`.
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**Example**:
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```javascript
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{ fetch: function (args, cb) {
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// cb(err) when there is an actual error (db, fs, etc)
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// cb(null, null) when the certificate was NOT available on disk
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// cb(null, { cert: '<fullchain.pem>', key: '<privkey.pem>', renewedAt: 0, duration: 0 }) cert + meta
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}
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, register: function (args, setChallenge, cb) {
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// setChallenge(hostnames, key, value, cb) when a challenge needs to be set
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// cb(err) when there is an error
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// cb(null, null) when the registration is successful, but fetch still needs to be called
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// cb(null, cert /*see above*/) if registration can easily return the same as fetch
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}
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}
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```
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#### bkDefaults
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The arguments passed here (typically `webpathRoot`, `configDir`, etc) will be merged with
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any `args` (typically `domains`, `email`, and `agreeTos`) and passed to the backend whenever
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it is called.
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Typically the backend wrapper will already merge any necessary backend-specific arguments.
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**Example**:
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```javascript
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{ webrootPath: __dirname, '/acme-challenge'
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, fullchainTpl: '/live/:hostname/fullchain.pem'
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, privkeyTpl: '/live/:hostname/fullchain.pem'
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, configDir: '/etc/letsencrypt'
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}
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```
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Note: `webrootPath` can be set as a default, semi-locally with `webrootPathTpl`, or per
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registration as `webrootPath` (which overwrites `defaults.webrootPath`).
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#### handlers *optional*
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`h.setChallenge(hostnames, name, value, cb)`:
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default is to write to fs
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`h.getChallenge(hostnames, value cb)`
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default is to read from fs
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`h.sniRegisterCallback(args, currentCerts, cb)`
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The default is to immediately call `cb(null, null)` and register (or renew) in the background
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during the `SNICallback` phase. Right now it isn't reasonable to renew during SNICallback,
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but around February when it is possible to use ECDSA keys (as opposed to RSA at present),
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registration will take very little time.
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This will not be called while another registration is already in progress.
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**SECURITY WARNING**: If you use this option with a custom `h.validate()`, make sure that `args.domains`
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refers to domains you expect, otherwise an attacker will spoof SNI and cause your server to rate-limit
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letsencrypt.org and get blocked. Note that `le.validate()` will check A records before attempting to
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register to help prevent such possible attacks.
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`h.validate(domains, cb)`
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When specified this will override `le.validate()`. You will need to do this if the ip address of this
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server is not one specified in the A records for your domain.
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### `le.middleware()`
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An express handler for `/.well-known/acme-challenge/<challenge>`.
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Will call `getChallenge([hostname], key, cb)` if present or otherwise read `challenge` from disk.
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Example:
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```javascript
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app.use('/', le.middleware())
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```
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### `le.sniCallback(hostname, function (err, tlsContext) {});`
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Will call `fetch`. If fetch does not return certificates or returns expired certificates
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it will call `sniRegisterCallback(args, currentCerts, cb)` and then return the error,
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the new certificates, or call `fetch` a final time.
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Example:
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```javascript
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var server = require('https').createServer({ SNICallback: le.sniCallback, cert: '...', key: '...' });
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server.on('request', app);
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```
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### `le.register({ domains, email, agreeTos, ... }, cb)`
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Get certificates for a domain
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Example:
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```javascript
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le.register({
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domains: ['example.com', 'www.example.com']
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, email: 'user@example.com'
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, webrootPath: '/srv/www/example.com/public'
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, agreeTos: true
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}, function (err, certs) {
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// err is some error
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console.log(certs);
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/*
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{ cert: "contents of fullchain.pem"
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, key: "contents of privkey.pem"
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, renewedAt: <date in milliseconds>
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, duration: <duration in milliseconds (90-days)>
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}
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*/
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});
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```
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### `le.isValidDomain(hostname)`
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returns `true` if `hostname` is a valid ascii or punycode domain name.
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(also exposed on the main exported module as `LetsEncrypt.isValidDomain()`)
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### `le.validate(args, cb)`
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Used internally, but exposed for convenience. Checks `LetsEncrypt.isValidDomain()`
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and then checks to see that the current server
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Called before `backend.register()` to validate the following:
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* the hostnames don't use any illegal characters
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* the server's actual public ip (via api.apiify.org)
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* the A records for said hostnames
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### `le.fetch(args, cb)`
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Used internally, but exposed for convenience.
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Checks in-memory cache of certificates for `args.domains` and calls then calls `backend.fetch(args, cb)`
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**after** merging `args` if necessary.
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### `le.registrationFailureCallback(err, args, certInfo, cb)`
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Not yet implemented
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Backends
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--------
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* [`letsencrypt-python`](https://github.com/Daplie/node-letsencrypt-python) (complete)
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* [`letiny`](https://github.com/Daplie/node-letiny) (in progress)
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#### How to write a backend
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A backend must implement (or be wrapped to implement) this API:
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* `fetch(hostname, cb)` will cb(err, certs) with certs from disk (or null or error)
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* `register(args, challengeCb, done)` will register and or renew a cert
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* args = `{ domains, email, agreeTos }` MUST check that agreeTos === true
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* challengeCb = `function (challenge, cb) { }` handle challenge as needed, call cb()
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This is what `args` looks like:
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```javascript
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{ domains: ['example.com', 'www.example.com']
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, email: 'user@email.com'
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, agreeTos: true
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, configDir: '/etc/letsencrypt'
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, fullchainTpl: '/live/:hostname/fullchain.pem' // :hostname will be replaced with the domainname
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, privkeyTpl: '/live/:hostname/privkey.pem'
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, webrootPathTpl: '/srv/www/:hostname/public'
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, webrootPath: '/srv/www/example.com/public' // templated from webrootPathTpl
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}
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```
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This is what the implementation should look like:
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(it's expected that the client will follow the same conventions as
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the python client, but it's not necessary)
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```javascript
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return {
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fetch: function (args, cb) {
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// NOTE: should return an error if args.domains cannot be satisfied with a single cert
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// (usually example.com and www.example.com will be handled on the same cert, for example)
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if (errorHappens) {
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// return an error if there is an actual error (db, etc)
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cb(err);
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return;
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}
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// return null if there is no error, nor a certificate
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else if (!cert) {
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cb(null, null);
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return;
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}
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// NOTE: if the certificate is available but expired it should be
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// returned and the calling application will decide to renew when
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// it is convenient
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// NOTE: the application should handle caching, not the library
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// return the cert with metadata
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cb(null, {
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cert: "/*contcatonated certs in pem format: cert + intermediate*/"
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, key: "/*private keypair in pem format*/"
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, renewedAt: new Date() // fs.stat cert.pem should also work
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, duration: 90 * 24 * 60 * 60 * 1000 // assumes 90-days unless specified
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});
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}
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, register: function (args, challengeCallback, completeCallback) {
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// **MUST** reject if args.agreeTos is not true
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// once you're ready for the caller to know the challenge
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if (challengeCallback) {
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challengeCallback(challenge, function () {
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continueRegistration();
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})
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} else {
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continueRegistration();
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}
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function continueRegistration() {
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// it is not necessary to to return the certificates here
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// the client will call fetch() when it needs them
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completeCallback(err);
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}
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}
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};
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```
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Change History
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==============
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v1.0.0 Thar be dragons
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LICENSE
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=======
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Dual-licensed MIT and Apache-2.0
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See LICENSE
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