ngrok

What is ngrok?

The ngrok npm package allows you to expose a local server to the internet securely. It is commonly used for testing webhooks, developing APIs, and sharing local websites. Ngrok provides a public URL that tunnels traffic to your local server, making it accessible from anywhere.

What are ngrok's main functionalities?

Expose Local Server

This feature allows you to expose a local server running on port 3000 to the internet. The ngrok.connect method creates a tunnel and returns a public URL.

const ngrok = require('ngrok');
(async function() {
  const url = await ngrok.connect(3000);
  console.log(`Server is publicly accessible at ${url}`);
})();

Custom Subdomains

This feature allows you to specify a custom subdomain for your public URL. This is useful for branding or easier access.

const ngrok = require('ngrok');
(async function() {
  const url = await ngrok.connect({ addr: 3000, subdomain: 'mycustomsubdomain' });
  console.log(`Server is publicly accessible at ${url}`);
})();

Secure Tunnels

This feature allows you to create secure HTTPS tunnels to your local server, ensuring that the data transmitted is encrypted.

const ngrok = require('ngrok');
(async function() {
  const url = await ngrok.connect({ addr: 3000, proto: 'https' });
  console.log(`Server is securely accessible at ${url}`);
})();

Inspect Traffic

Ngrok provides a web interface to inspect the traffic going through your tunnels. This is useful for debugging and monitoring.

const ngrok = require('ngrok');
(async function() {
  const url = await ngrok.connect(3000);
  console.log(`Server is publicly accessible at ${url}`);
  console.log(`Inspect traffic at http://127.0.0.1:4040`);
})();

Other packages similar to ngrok

localtunnel

Localtunnel allows you to easily share a local server with the world. It provides a public URL that tunnels traffic to your local server. Compared to ngrok, Localtunnel is simpler and has fewer features but is easier to set up.

serveo

Serveo is another tool for exposing local servers to the internet. It uses SSH to create tunnels, which can be more secure. Serveo does not require any installation and can be used directly from the command line.

README

ngrok

• Usage
  • Local install
  • Global install
  • Auth Token
  • Connect
    • Options
  • Disconnect
  • Config
  • Inspector
  • API
    • List tunnels
    • Start tunnel
    • Get tunnel details
    • Stop tunnel
    • List requests
    • Replay request
    • Delete all requests
    • Request detail
  • Proxy
• How it works
• ngrok binary update
• Using with nodemon
• Contributors
• Upgrading to version 4
  • TypeScript

Usage

Local install

Install the package with npm:

npm install ngrok

Then use ngrok.connect() to start ngrok and open a tunnel.

const ngrok = require('ngrok');
(async function() {
  const url = await ngrok.connect();
})();

This module uses node>=10.19.0 with async/await. For a callback-based version use 2.3.0.

Global install

npm install ngrok -g
ngrok http 8080

For global install on Linux, you might need to run sudo npm install --unsafe-perm -g ngrok due to the nature of npm postinstall script.

Auth Token

You can create basic http-https-tcp tunnel without an authtoken. For custom subdomains and more you should obtain an authtoken by signing up at ngrok.com. Once you set the authtoken, it is stored in ngrok config and used for all tunnels. You can set the authtoken directly:

await ngrok.authtoken(token);

Or pass the authtoken to the connect method like so:

await ngrok.connect({authtoken: token, ...});

Connect

There are a number of ways to create a tunnel with ngrok using the connect method.

By default, connect will open an HTTP tunnel to port 80

const url = await ngrok.connect(); // https://757c1652.ngrok.io -> http://localhost:80

You can pass the port number to connect to specify that port:

const url = await ngrok.connect(9090); // https://757c1652.ngrok.io -> http://localhost:9090

Or you can pass an object of options, for example:

const url = await ngrok.connect({proto: 'tcp', addr: 22}); // tcp://0.tcp.ngrok.io:48590
const url = await ngrok.connect(opts);

Options

There are many options that you can pass to connect, here are some examples:

const url = await ngrok.connect({
  proto: 'http', // http|tcp|tls, defaults to http
  addr: 8080, // port or network address, defaults to 80
  auth: 'user:pwd', // http basic authentication for tunnel
  subdomain: 'alex', // reserved tunnel name https://alex.ngrok.io
  authtoken: '12345', // your authtoken from ngrok.com
  region: 'us', // one of ngrok regions (us, eu, au, ap, sa, jp, in), defaults to us
  configPath: '~/git/project/ngrok.yml', // custom path for ngrok config file
  binPath: path => path.replace('app.asar', 'app.asar.unpacked'), // custom binary path, eg for prod in electron
  onStatusChange: status => {}, // 'closed' - connection is lost, 'connected' - reconnected
  onLogEvent: data => {}, // returns stdout messages from ngrok process
});

See the ngrok documentation for all of the tunnel definition options including: name, inspect, host_header, bind_tls, hostname, crt, key, client_cas, remote_addr.

Note on regions: the region used in the first tunnel will be used for all the following tunnels.

Disconnect

The ngrok process and all tunnels will be killed when node process is complete. To stop the tunnels manually use:

await ngrok.disconnect(url); // stops one
await ngrok.disconnect(); // stops all
await ngrok.kill(); // kills ngrok process

Note on HTTP tunnels: by default bind_tls is true, so whenever you use HTTP proto two tunnels are created - HTTP and HTTPS. If you disconnect the HTTPS tunnel, the HTTP tunnel remains open. You might want to close them both by passing the HTTP-version url, or simply by disconnecting all in one go ngrok.disconnect().

Config

You can use ngrok's configurations files, and pass name option when making a tunnel. Configuration files allow to store tunnel options. Ngrok looks for them here:

OS X	/Users/example/.ngrok2/ngrok.yml
Linux	/home/example/.ngrok2/ngrok.yml
Windows	C:\Users\example\.ngrok2\ngrok.yml

You can specify a custom configPath when making a tunnel.

Inspector

When a tunnel is established you can use the ngrok interface hosted at http://127.0.0.1:4040 to inspect the webhooks made via ngrok.

The same URL hosts the internal client api. This package exposes an API client that wraps the API which you can use to manage tunnels yourself.

const url = await ngrok.connect();
const api = ngrok.getApi();
const tunnels = await api.listTunnels();

You can also get the URL of the internal API:

const url = await ngrok.connect();
const apiUrl = ngrok.getUrl();

API

The API wrapper gives access to all the ngrok client API methods:

const url = await ngrok.connect();
const api = ngrok.getApi();

List tunnels

const tunnels = await api.listTunnels();

Start tunnel

const tunnel = await api.startTunnel(opts);

Get tunnel details

const tunnel = await api.tunnelDetail(tunnelName);

Stop tunnel

await api.stopTunnel(tunnelName);

List requests

await api.listRequests(options);

Replay request

await api.replayRequest(requestId, tunnelName);

Delete all requests

await api.deleteAllRequests();

Request detail

const request = await api.requestDetail(requestId);

Proxy

• If you are behind a corporate proxy and have issues installing ngrok, you can set HTTPS_PROXY env var to fix it. ngrok's postinstall scripts uses the got module to fetch the binary and the hpagent module to support HTTPS proxies. You will need to install the hpagent module as a dependency
• If you are using a CA file, set the path in the environment variable NGROK_ROOT_CA_PATH. The path is needed for downloading the ngrok binary in the postinstall script

How it works

npm install downloads the ngrok binary for your platform from the official ngrok hosting. To host binaries yourself set the NGROK_CDN_URL environment variable before installing ngrok. To force specific platform set NGROK_ARCH, eg NGROK_ARCH=freebsdia32.

The first time you create a tunnel the ngrok process is spawned and runs until you disconnect or when the parent process is killed. All further tunnels are connected or disconnected through the internal ngrok API which usually runs on http://127.0.0.1:4040.

ngrok binary update

If you would like to force an update of the ngrok binary directly from your software, you can require the ngrok/download module and call the downloadNgrok function directly:

const downloadNgrok = require('ngrok/download');
downloadNgrok(myCallbackFunc, { ignoreCache: true });

Using with nodemon

If you want your application to restart as you make changes to it, you may use nodemon. This blog post shows how to use nodemon and ngrok together so your server restarts but your tunnel doesn't.

Contributors

Please run git update-index --assume-unchanged bin/ngrok to not override ngrok stub in your PR. Unfortunately it can't be gitignored.

The test suite covers the basic usage without an authtoken, as well as features available for free and paid authtokens. You can supply your own tokens as environment variables, otherwise a warning is given and some specs are ignored (locally and in PR builds). GitHub Actions supplies real tokens to master branch and runs all specs always.

Upgrading to version 4

The main impetus to update the package was to remove the dependency on the deprecated request module. request was replaced with got. Calls to the main ngrok functions, connect, authtoken, disconnect, kill, getVersion and getUrl respond the same as in version 3.

Updating the HTTP library, meant that the wrapped API would change, so a client class was created with methods for the available API calls. See the documentation above for how to use the API client.

The upside is that you no longer have to know the path to the API method you need. For example, to list the active tunnels in version 3 you would do:

const api = ngrok.getApi();
const tunnels = await api.get('api/tunnels');

Now you can call the listTunnels function:

const api = ngrok.getApi();
const tunnels = await api.listTunnels();

TypeScript

From version 3 to version 4 the bundled types were also overhauled. Most types live within the Ngrok namespace, particularly Ngrok.Options which replaces INgrokOptions.

Changelog

[4.3.3] - 2022-08-18

Fixed

• Removed old ngrok.d.ts from package.json files and added index.d.ts