Exposing a Local Spring Boot App to the Web with Ngrok

Exposing a local Spring Boot app to the web has never been easier. In this guide, we’ll equip you with all the necessary information to seamlessly expose your local Spring Boot app over the web using Ngrok.

Introduction

Have you ever wanted to show your Spring Boot web app to a friend or colleague, but they’re not sitting right next to you? Well, fear not! With Ngrok, you can expose your local Spring Boot app to the internet in just a few simple steps.

What is Ngrok?

Ngrok is a powerful tool that allows you to expose a web server running on your local machine to the internet. It is a tool that creates a secure tunnel to your local machine and gives it a public URL. This means anyone with that URL can access your locally hosted web app as if it were live on the internet. It’s incredibly useful for testing and sharing your applications during development.

Use Cases for Ngrok

Ngrok isn’t just a tool for sharing your Spring Boot app with friends. It has a variety of use cases that make it incredibly handy for developers and testers alike. Here are a few scenarios where Ngrok can be useful:

1. Demoing Web Sites Without Deploying: Ngrok allows you to share your local web applications with others without deploying them to a public server. This is perfect for showcasing your work-in-progress to clients, colleagues, or stakeholders.

2. Building Webhook Consumers on Your Dev Machine: When working with webhooks (e.g., receiving data from third-party services), Ngrok lets you test and debug webhook endpoints directly on your local machine. You can simulate incoming requests and ensure your application handles them correctly.

3. Testing Mobile Apps Connected to Your Locally Running Backend: Developing a mobile app that communicates with a backend server? Ngrok can help you test the interaction between your mobile app and the backend server in real time, even if the server is running on your local machine.

4. Stable Addresses for Connected Devices Deployed in the Field: Suppose you have IoT devices or sensors deployed in the field. Ngrok provides a consistent and secure URL for these devices, allowing you to monitor and manage them remotely. The consistent URL feature is available exclusively in the paid plan.

5. Running Personal Cloud Services from Your Home: Want to access your home server or Raspberry Pi from anywhere? Ngrok lets you create a public URL for services running on your local network, such as home automation systems or personal websites.

Prerequisites

Before you begin with Ngrok, make sure you have a working Spring Boot application ready to go. If you haven’t created one yet, you can refer to our blog on creating a Spring Boot “Hello, World!” application, which includes all the necessary information and codebase to get started.

Steps to Exposing a Local Spring Boot App

Step 1: Sign Up on Ngrok

Go to Ngrok’s website and sign up for an account. It’s free!

Step 2: Download Ngrok

Download Ngrok for your operating system (Windows, macOS, or Linux) from here. Once downloaded, unzip the file and you’re good to go.

Step 3: Connect Your Account

To begin, open a terminal window and navigate to the directory where you have extracted Ngrok. Once there, execute the command provided below to establish a connection with your Ngrok account:

./ngrok authtoken YOUR_AUTH_TOKEN

Remember to replace “YOUR_AUTH_TOKEN” with the token you receive after signing up on Ngrok. If you haven’t acquired your token yet, you can obtain it from https://dashboard.ngrok.com/get-started/your-authtoken.

Example:

Ngrok Set Auth Token

Step 4: Start Your Spring Boot App

Fire up your Spring Boot application as you normally would. Make sure it’s running smoothly on your local machine.

Step 5: Expose Your App

In the same terminal window that was opened earlier, execute the following command:

./ngrok http PORT

Replace “PORT” with the specific port number where your Spring Boot application is running (for example, 8080). Ngrok will then generate a public URL for you, resembling something like https://randomlettersandnumbers.ngrok-free.app. This URL allows others to access your Spring Boot app over the web/internet, even if it is running on your local system.

Example:

Start Ngrok

Step 6: Share the URL

That’s it! You now have a public URL that can be shared with anyone who wishes to test or access your Spring Boot app over the internet.

Example:

Expose Spring Boot App

Step 7: Don’t Forget to Stop Ngrok

Once you’ve finished presenting your app, don’t forget to stop Ngrok by pressing Ctrl + C in the terminal window where Ngrok is running. This will close the tunnel and deactivate the public URL.

Web Interface and Traffic Inspector

Ngrok’s web interface offers users a convenient platform to monitor their tunnels effortlessly. Through this interface, users gain visibility into active tunnels and can access vital information regarding HTTP traffic. The traffic inspector feature enables users to analyze incoming HTTP requests in real time, providing valuable insights for debugging and troubleshooting.

The web interface can be accessed at http://127.0.0.1:4040 or http://localhost:4040 and the traffic inspector can be accessed at https://ngrok.com/r/ti.

Example:

Ngrok Web Interface UINgrok Traffic Inspector

Expose Spring Boot Ap

Things to Consider

Here are some things to consider when using Ngrok:

• Security: While Ngrok provides convenient access to your local development environment, be mindful of security implications, especially when exposing sensitive data or services to the internet. Ensure proper authentication and encryption measures are in place to protect your information.
• Rate Limits: Ngrok offers free and paid plans with different rate limits. Be aware of these limits, especially if you anticipate heavy usage, and consider upgrading to a paid plan if necessary to avoid disruptions in service.
• Session Persistence: Ngrok’s free plan doesn’t guarantee session persistence, meaning the public URL may change after each restart. Evaluate if session persistence is critical for your use case.
• Custom Subdomains: Paid plans of Ngrok offer the ability to use custom subdomains, providing a more branded and stable URL. Evaluate whether this feature aligns with your branding and usability requirements.
• Compliance: Ensure compliance with regulations and policies when exposing your application to the internet. Consider data privacy laws and industry standards applicable to your project.

FAQs

Conclusion

In summary, Ngrok makes it easy to share and test local Spring Boot apps over the internet. With its user-friendly interface and versatile features, developers can collaborate effectively and accelerate their project development workflows.

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