Скачать или смотреть Solving the 403 Error in Spring Boot CORS Configuration

Learn how to troubleshoot and resolve a `403 Forbidden` error when making GET requests in a Spring Boot application with CORS enabled.
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Understanding the 403 Forbidden Error in Spring Boot CORS

When working with a Spring Boot application, you may encounter a perplexing issue where your application consistently returns a 403 Forbidden status code for GET requests, especially when the Origin header is set to something other than the web application's own hostname. If you've enabled Cross-Origin Resource Sharing (CORS) for specific endpoints, this can be frustrating – especially when it seems like everything is set up correctly. This guide will guide you through diagnosing and fixing this issue.

The Problem

In your Spring Boot application, while enabling CORS for a subset of endpoints, you may notice successful preflight requests, but actual GET requests yield a 403 Forbidden status without any detailed logging. The logging might reveal successful authorization, yet no additional information on the failure reason is provided. This situation can be perplexing because it seems that everything should work fine.

Key Observations:

Requests to endpoints matched by /path/** generate the 403 error when an Origin header other than the hostname is specified.

Requests without the Origin header or matching the hostname succeed, indicating there's an issue with how CORS is set up on the server.

Configuration Review

Before troubleshooting further, let's examine the current CORS configuration within the WebSecurityConfigurerAdapter:

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

Configuration Breakdown:

setAllowedOrigins(Collections.singletonList("*")) - This indicates that requests from any origin should be allowed.

setAllowedMethods(Arrays.asList(...)) - This section lists all HTTP methods that the server will allow.

setAllowCredentials(true) - Indicates that the server allows credentials such as cookies to be sent.

Other Considerations

One crucial detail that's often overlooked is whether there are other filters or configurations interfering with the expected CORS behavior.

The Solution

Here’s the resolution that ultimately fixed the issue: re-evaluate and adjust CORS handling in your application’s context.

Step-by-step Resolution:

Check for Existing Filters: Review the web.xml file or any configuration files that might be defining CORS filters. Filters defined here can interfere with the Spring Boot configuration.

Remove Conflicting Filters: If you find a filter specified in web.xml, consider removing it so that Spring can manage CORS completely within your application context.

Test the Configuration: After removing the conflicting CORS filter, test your GET requests again. The expected 200 OK status should return for requests made with valid CORS settings.

Additional Troubleshooting:

Enable Detailed Logging: Further enable logging for CORS processing. This can provide insight into whether the CORS handling is working as intended.

Cross-Origin Requests: Ensure that the planned use of cross-origin requests is explicitly allowed in your security configurations.

Conclusion

By understanding CORS behaviors and thoroughly checking your application configurations, you can effectively resolve the 403 Forbidden error in Spring Boot. The discovery of conflicting configurations, like a web.xml CORS filter, is a fundamental step toward creating a seamless cross-origin experience for your web applications. If you're still encountering issues, consider looking deeper into your configurations or enabling more extensive logging to pinpoint the problem areas.

If you found this guide helpful or have other tips on troubleshooting Spring Boot and CORS issues, feel free to share your thoughts in the comments!