Скачать или смотреть Resolving the Spring Boot Admin Custom View Not Found Issue in a WAR Deployment

Discover how to fix the `Spring Boot Admin` custom view not found issue when deploying as a WAR into Tomcat, with detailed steps and explanations.
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Troubleshooting Custom View Issues in Spring Boot Admin

When deploying applications with Spring Boot, issues can frequently arise, especially when transitioning from a JAR to a WAR deployment in environments like Tomcat. One such common problem is the inability to display custom views in the Spring Boot Admin (SBA) dashboard. This guide will walk you through the troubleshooting steps and solutions to fix custom view not found errors that may occur during this transition.

The Problem at Hand

Upon deploying your Spring Boot Admin application as a WAR file into Tomcat, you might find that your customized dashboard views are not loading as expected. Specifically, you may encounter an error message stating that certain resources are not found (404 errors), like so:

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This issue can be puzzling, particularly if the views were functioning correctly in a JAR deployment. However, this problem can often be traced back to how resource paths are managed in the context of a WAR deployment.

Exploring the Root Cause

The root of the issue lies in the handling of resource paths within the Spring Boot Admin UI. When you deploy the application, the paths for resource extensions are defined in the AdminServerUiAutoConfiguration class. This class sets mappings for where the server should look for extensions based on certain context paths.

Key Findings:

The default location for these extensions is determined by spring.boot.admin.ui.extension-resource-locations, which typically points to classpath:/META-INF/spring-boot-admin-server-ui/extensions/.

However, the actual implementation in index.html uses absolute paths instead of relative ones, which can create issues in certain deployed environments.

How to Fix the Issues

To resolve the custom view not found errors, you may need to adapt the way resource paths are declared in your Spring Boot Admin UI. Here are the steps you can follow:

Step 1: Update Resource Paths

You will need to modify the index.html file located at spring-boot-admin-server-ui/src/main/frontend/index.html. Look for the sections that define how CSS and JavaScript extensions are handled:

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Replace these lines with relative paths. Instead of using absolute paths, you want to use a format that incorporates the context path.

Step 2: Clone and Modify the Spring Boot Admin

After making changes to the index.html, clone the Spring Boot Admin repository for the version you are using (e.g., tag 2.2.3). Apply your modifications and run a Maven build to generate your updated WAR file:

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Step 3: Redeploy your Application

Once you have rebuilt the WAR file, redeploy it into Tomcat. Check that your context paths are correctly set in your application properties to match this new deployment structure.

Quick Recap

Identify Absolute Paths: Locate parts in your HTML source where absolute paths are used.

Change to Relative Paths: Adjust these absolute paths to be relative, taking into consideration your server's context paths.

Rebuild and Redeploy: Build the changes and redeploy to ensure the server picks up the new settings.

Conclusion

Deploying Spring Boot Admin applications as WAR files can lead to some tricky path management issues. By following the steps outlined in this guide, you should be able to resolve custom view not found errors effectively. Remember, adapting the resource path handling in your HTML file is key to ensuring your custom views and assets are accessible in your deployed environment.

If you continue to encounter difficulties or have additional questions, don’t hesitate to seek further assistance. Happy codin