Download ngrok

package com.example;

import com.ngrok.Session;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;


public class App {
	public static void main(final String[] args) throws IOException {
		// Session.withAuthtokenFromEnv() will create a new session builder, pulling NGROK_AUTHTOKEN env variable.
		// You can get your authtoken by registering at https://dashboard.ngrok.com
		final var sessionBuilder = Session.withAuthtokenFromEnv().metadata("my session");
		// UTF-8 for encoding
		final Charset utf8 = Charset.forName("UTF-8");
		// Session.Builder let you customize different aspects of the session, see docs for details.
		// After customizing the builder, you connect:
		try (final var session = sessionBuilder.connect()) {
			// Creates and configures http listener that will be using oauth to secure it
			final var listenerBuilder = session.httpEndpoint().metadata("my listener");

			// Now start listening with the above configuration
			try (final var listener = listenerBuilder.listen()) {
				System.out.println("ngrok url: " + listener.getUrl());
				final var buf = ByteBuffer.allocateDirect(1024);

				while (true) {
					// Accept a new connection
					final var conn = listener.accept();

					// Read from the connection
					buf.clear();
					conn.read(buf);

					System.out.println(utf8.decode(buf));

					// Or write to it
					buf.clear();
					buf.put("HTTP/1.0 200 OK\n\nHello from ngrok!".getBytes(utf8));
					buf.flip();
					conn.write(buf);
					conn.close();
				}
			}
		}
	}
}

NGROK_AUTHTOKEN=<token> mvn clean install