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https://github.com/alexdlaird/java-ngrok-example-dropwizard

Dropwizard example for java-ngrok
https://github.com/alexdlaird/java-ngrok-example-dropwizard

dropwizard education java java-ngrok localhost localtunnel ngrok reverse-proxy tunnel tunneling webhook

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Dropwizard example for java-ngrok

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[![Build](https://img.shields.io/github/actions/workflow/status/alexdlaird/java-ngrok-example-dropwizard/build.yml)](https://github.com/alexdlaird/java-ngrok-example-dropwizard/actions/workflows/build.yml)

![GitHub License](https://img.shields.io/github/license/alexdlaird/java-ngrok-example-dropwizard)



# java-ngrok Example - Dropwizard



This is an example project that shows how to easily integrate [`java-ngrok`](https://github.com/alexdlaird/java-ngrok)

with [Dropwizard](https://www.dropwizard.io/en/latest/index.html).



## Configuration



Create

a [`NgrokConfiguration`](https://github.com/alexdlaird/java-ngrok-example-dropwizard/blob/main/src/main/java/com/github/alexdlaird/conf/NgrokConfiguration.java)

class that lets us use the config to enable `ngrok` and pass it some useful parameters.



```java

public class NgrokConfiguration {

    @JsonProperty

    private boolean enabled = false;



    @JsonProperty

    private String region;



    public boolean isEnabled() {

        return enabled;

    }



    public String getRegion() {

        return region;

    }

}

```



Then wire this class as a `JsonProperty`

to [the Dropwizard Configuration for our Application](https://www.dropwizard.io/en/latest/getting-started.html#creating-a-configuration-class).



```java

public class JavaNgrokExampleDropwizardConfiguration extends Configuration {

    @JsonProperty

    private String environment = "dev";



    @JsonProperty("ngrok")

    private NgrokConfiguration ngrokConfiguration;



    public String getEnvironment() {

        return environment;

    }



    public NgrokConfiguration getNgrokConfiguration() {

        return ngrokConfiguration;

    }

}

```



And pass parameters to our Dropwizard application through

[our config file](https://github.com/alexdlaird/java-ngrok-example-dropwizard/blob/main/config.yml):



```yaml

ngrok:

  enabled: true

```



## Application Integration



If `ngrok.enabled` config flag is set, we want to initialize `java-ngrok` when Dropwizard is booting. An easy place to do

this is in the `run()` method of [the Application](https://github.com/alexdlaird/java-ngrok-example-dropwizard/blob/main/src/main/java/com/github/alexdlaird/JavaNgrokExampleDropwizardApplication.java).



```java

public class JavaNgrokExampleDropwizardApplication extends Application {



    private static final Logger LOGGER = Logger.getLogger(String.valueOf(JavaNgrokExampleDropwizardApplication.class));



    @Override

    public void run(final JavaNgrokExampleDropwizardConfiguration configuration,

                    final Environment environment) {

        // java-ngrok will only be installed, and should only ever be initialized, in a dev environment

        if (configuration.getEnvironment().equals("dev") &&

                configuration.getNgrokConfiguration().isEnabled() &&

                isNotBlank(System.getenv("NGROK_AUTHTOKEN"))) {

            final JavaNgrokConfig javaNgrokConfig = new JavaNgrokConfig.Builder()

                    .withRegion(nonNull(configuration.getNgrokConfiguration().getRegion()) ? Region.valueOf(configuration.getNgrokConfiguration().getRegion().toUpperCase()) : null)

                    .build();

            final NgrokClient ngrokClient = new NgrokClient.Builder()

                    .withJavaNgrokConfig(javaNgrokConfig)

                    .build();



            final int port = getPort(configuration);



            final CreateTunnel createTunnel = new CreateTunnel.Builder()

                    .withAddr(port)

                    .build();

            final Tunnel tunnel = ngrokClient.connect(createTunnel);



            LOGGER.info(String.format("ngrok tunnel \"%s\" -> \"http://127.0.0.1:%d\"", tunnel.getPublicUrl(), port));



            // Update any base URLs or webhooks to use the public ngrok URL

            initWebhooks(tunnel.getPublicUrl());

        }

    }



    private int getPort(JavaNgrokExampleDropwizardConfiguration configuration) {

        final Stream connectors = configuration.getServerFactory() instanceof DefaultServerFactory

                ? ((DefaultServerFactory) configuration.getServerFactory()).getApplicationConnectors().stream()

                : Stream.of((SimpleServerFactory) configuration.getServerFactory()).map(SimpleServerFactory::getConnector);



        return connectors.filter(connector -> connector.getClass().isAssignableFrom(HttpConnectorFactory.class))

                .map(connector -> (HttpConnectorFactory) connector)

                .mapToInt(HttpConnectorFactory::getPort)

                .findFirst()

                .orElseThrow(IllegalStateException::new);

    }



    private void initWebhooks(final String publicUrl) {

        // Update inbound traffic via APIs to use the public-facing ngrok URL

    }



    // ... The rest of our Dropwizard application

}

```



Now Dropwizard can be started by the usual means, setting `ngrok.enabled` in the config to open a tunnel.



1. Run `make build` to build the application

1. Start application with `java -jar target/java-ngrok-example-dropwizard-1.0.0-SNAPSHOT.jar server src/main/resources/config.yml`

1. Check the logs for the `ngrok` tunnel's public URL, which should tunnel to  `http://localhost:8080`