java-ngrok is a Java wrapper for ngrok that manages its own binary, making ngrok available via a convenient Java API.
ngrok is a reverse proxy that opens secure tunnels from public URLs to localhost. It’s perfect for rapid development (test webhooks, demo local websites, enable SSH access), establishing ingress to external networks and devices, building production APIs (traffic policies, OAuth, load balancing), and more. And it’s made even more powerful with native Java integration through the java-ngrok client.
Installation
java-ngrok is available on Maven Central.
If you want ngrok to be available from the command line, pyngrok can be installed using pip to manage that for you.
Basic Usage
Open a Tunnel
To open a tunnel, use the NgrokClient‘s connect() method, which returns a Tunnel, and this returned object has a reference to the public URL generated by ngrok, which can be retrieved with getPublicUrl().
final NgrokClient ngrokClient = new NgrokClient.Builder().build();
// Open a HTTP tunnel on the default port 80
// <Tunnel: "https://<public_sub>.ngrok.io" -> "http://localhost:80">
final Tunnel httpTunnel = ngrokClient.connect();
// Open a SSH tunnel
// <Tunnel: "tcp://0.tcp.ngrok.io:12345" -> "localhost:22">
final CreateTunnel sshCreateTunnel = new CreateTunnel.Builder()
.withProto(Proto.TCP)
.withAddr(22)
.build();
final Tunnel sshTunnel = ngrokClient.connect(sshCreateTunnel);
// Open a named tunnel from the config file
final CreateTunnel createNamedTunnel = new CreateTunnel.Builder()
.withName("my-config-file-tunnel")
.build();
final Tunnel namedTunnel = ngrokClient.connect(createNamedTunnel);
// Open an Internal Endpoint that's load balanced
// <Tunnel: "https://some-endpoint.internal" -> "http://localhost:9000">
final CreateTunnel createInternalEndpoint = new CreateTunnel.Builder()
.withAddr("9000")
.withDomain("some-endpoint.internal")
.withPoolingEnabled(true)
.build();
final Tunnel internalEndpoint = ngrokClient.connect(createInternalEndpoint);
The connect() method can also take a CreateTunnel (which can be built through its Builder) that allows you to pass additional properties that are supported by ngrok (or withName() to use a tunnel defined in ngrok‘s config file), as documented here.
ngrok‘s API
The api() method allows you to use the local ngrok agent to make requests against the ngrok API, if you have set an API key. For example, here’s how you would reserve a ngrok domain, then create a Cloud Endpoint with an associated traffic policy:
final NgrokClient ngrokClient = new NgrokClient.Builder().build();
final String domain = "some-domain.ngrok.dev";
final ApiResponse domainResponse = ngrokClient.api(
List.of("reserved-domains", "create",
"--domain", domain));
final ApiResponse endpointResponse = ngrokClient.api(
List.of("endpoints", "create",
"--bindings", "public",
"--url", String.format("https://%s", domain),
"--traffic-policy-file", "policy.yml"));
Command Line Usage
Assuming you have also installed pyngrok, all features of ngrok are available on the command line.
ngrok http 80
For details on how to fully leverage ngrok from the command line, see ngrok‘s official documentation.
Documentation
For more advanced usage, java-ngrok‘s official documentation is available here on GitHub, with additional API documentation on javadoc.io.
Integration Examples
Java 8
A Java 8-compatible build was previously maintained in the 1.4.x branch. While it is no longer supported, it is available through the java8-ngrok artifact instead on Maven Central.
For more details on what differs in the java8-ngrok dependency, see the “Java 8” section of the docs.
Contributing
If you would like to get involved, be sure to review the Contribution Guide.
Want to contribute financially? If you’ve found java-ngrok useful, sponsorship would also be greatly appreciated!
