How to Fix Swagger springdoc-openapi-ui Not Working When Running Spring Boot as JAR

Learn how to resolve the `Swagger springdoc-openapi-ui` issues that arise when running a Spring Boot application as a JAR file, ensuring your API documentation is accessible.
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Troubleshooting Swagger springdoc-openapi-ui in Spring Boot JAR

If you've ever encountered an issue where your Swagger UI works perfectly while running your Spring Boot application from an IDE, but falls flat when you try to run it as a JAR file, you’re not alone! Let’s dive into the problem and explore how you can get your Swagger documentation working seamlessly, even when executing your application from the command line.

The Problem at a Glance

You may find that when running your Spring Boot application using the command:

[[See Video to Reveal this Text or Code Snippet]]

The Swagger UI becomes unresponsive or shows a broken interface, while it operates flawlessly when launched through your IDE or with the Maven Plugin. This can be frustrating, especially when you need to showcase your API documentation.

Common Symptoms of the Issue

Swagger UI URL access fails: Common URLs like:

yield a broken interface or simply do not respond.

No indication of Swagger initialization: You might notice logs relating to Swagger initialization do not appear when you start the application using the JAR method.

Solution Overview

The good news is that this issue can often be resolved by modifying your project’s build configuration. Specifically, it involves switching from using the maven-assembly-plugin to the spring-boot-maven-plugin. Let’s delve into the solution step by step.

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Key Changes Made

Remove maven-assembly-plugin: Ensure that the maven-assembly-plugin is removed or commented out, as it may interfere with how Spring Boot packages your application.

Repackage Configuration: The repackage goal is essential for creating a proper executable JAR that contains all required dependencies, including Swagger.

Step 2: Rebuild Your Application

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This command will compile your code and package it into a JAR file with all dependencies included.

Step 3: Verify the JAR Execution

Now that your application is rebuilt, attempt to run it again using the JAR command:

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Access Swagger UI

Once your application is up and running, try accessing Swagger UI at:

You should see your Swagger UI interface properly rendered!

Conclusion

Feel free to share your experiences or ask questions in the comments below!