Koa SSLify

Enforce HTTPS middleware for Koa.js

Koa.js middleware to enforce HTTPS connection on any incoming requests. In case of a non-encrypted HTTP request, koa-sslify automatically redirects to an HTTPS address using a 301 permanent redirect (or optionally 307 Temporary Redirect).

Koa SSLify can also work behind reverse proxies (load balancers) like on Heroku, Azure, GCP Ingress etc and supports custom implementations of proxy resolvers.

Install

$ npm install --save koa-sslify

Usage

Importing default factory function:

const sslify = require('koa-sslify').default; // factory with default options
const Koa = require('koa');

app = new Koa();
app.use(sslify());

Default function accepts several options.

Name	Type	Default	Description
resolver	Function	httpsResolver	Function used to test if request is secure
hostname	Function	undefined	Function that takes the request hostname string as its only argument and returns the desired hostname to use as a result. Uses request hostname if not set or return value is falsy
port	Integer	443	Port of HTTPS server
ignoreUrl	Boolean	false	Ignore url path (redirect to domain)
temporary	Boolean	false	Temporary mode (use 307 Temporary Redirect)
skipDefaultPort	Boolean	true	Avoid :443 port in redirect url
redirectMethods	Array	['GET', 'HEAD']	Whitelist methods that should be redirected
disallowStatus	Integer	405	Status returned for disallowed methods

Resolvers

Resolver is a function from classic Koa ctx object to boolean. This function is used to determine if request is or is not secured (true means is secure). Middleware calls this function and based on its returned value either passes control to next middleware or responds to the request with appropriate redirect response.

There are several resolvers provided by this library but it should be very easy to implement any type of custom check as well.

for instance, Heroku has a reverse proxy that uses x-forwarded-proto header. This is how you can configure app with this resolver:

const {
  default: sslify, // middleware factory
  xForwardedProtoResolver: resolver // resolver needed
} = require('koa-sslify');
const Koa = require('koa');

app = new Koa();

// init middleware with resolver
app.use(sslify({ resolver }));

Those are all resolver provided by default:

Name	Used by	Example
httpsResolver	Node.js server running with TLS support	sslify()
xForwardedProtoResolver	Heroku, Google Ingress	sslify({ resolver: xForwardedProtoResolver })
azureResolver	Azure	sslify({ resolver: azureResolver })
customProtoHeaderResolver	any non-standard implementation (Kong)	sslify({ resolver: customProtoHeader('x-protocol') })
forwardedResolver	standard header	sslify({ resolver: forwardedResolver })

Some additional information about reverse proxies:

Reverse Proxies (Heroku, GCE Ingress and others)

Heroku, GCE Ingress and other hosters often use reverse proxies which offer SSL endpoints but then forward unencrypted HTTP traffic to the website. This makes it difficult to detect if the original request was indeed via HTTPS. Luckily, most reverse proxies set the x-forwarded-proto header flag with the original request scheme.

Azure

Azure has a slightly different way of signaling encrypted connections. It uses x-arr-ssl header as a flag to mark https traffic.

Defining Custom Resolver

If you're still in a situation where you need to use custom resolver you can implement it as for example following:

const { default: sslify } = require('koa-sslify');

app.use(sslify({
  resolver: (ctx) => ctx.request.header['x-is-secure'] === 'yup!'
}))

Contributions to increase coverage of default resolvers are welcomed.

Examples

Those are full example apps using Koa SSLify to enforce HTTPS.

Without Reverse Proxy

This example starts 2 servers for app.

• First HTTP server is listening on port 8080 and redirects to second one
• Second HTTPS server is listening on port 8081

const Koa = require('koa');
const http = require('http');
const https = require('https');
const fs = require('fs');
const { default: enforceHttps } = require('koa-sslify');

const app = new Koa();

// Force HTTPS using default resolver
app.use(enforceHttps({
  port: 8081
}));

// index page
app.use(ctx => {
  ctx.body = "hello world from " + ctx.request.url;
});

// SSL options
var options = {
  key: fs.readFileSync('server.key'),
  cert: fs.readFileSync('server.crt')
}

// start the server
http.createServer(app.callback()).listen(8080);
https.createServer(options, app.callback()).listen(8081);

With Reverse Proxy

This example starts a single http server which is designed to run behind a reverse proxy like Heroku.

const Koa = require('koa');
const {
  default: enforceHttps,
  xForwardedProtoResolver: resolver
} = require('koa-sslify');

var app = new Koa();

// Force HTTPS via x-forwarded-proto compatible resolver
app.use(enforceHttps({ resolver }));

// index page
app.use((ctx) => {
  ctx = "hello world from " + ctx.request.url;
});

// proxy will bind this port to it's 443 and 80 ports
app.listen(3000);

Advanced Redirect Setting

Redirect Methods

By default only GET and HEAD methods are whitelisted for redirect. koa-sslify will respond with 405 with appropriate Allow header by default. You can change whitelisted methods by passing redirectMethods array to options as well as change status for disallowed methods using disallowStatus.

Skip Default Port in Redirect URL

By default port is excluded from redirect url if it's set to 443. Since 443 is default port for HTTPS browser will use it by default anyway so there is no need to explicitly return it as part of URL. Anyway in case you need to always return port as part of URL string you can pass options with skipDefaultPort: false to do the trick.

License

MIT

Credits

This project is heavily inspired by Florian Heinemann's express-sslify and Vitaly Domnikov's koa-force-ssl.