Скачать или смотреть Resolving CORS Errors When Connecting Angular to Spring Security OAuth Server

Learn how to troubleshoot and resolve `CORS` errors in your Angular app interacting with a `Spring Security OAuth2` server effectively.
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Resolving CORS Errors When Connecting Angular to Spring Security OAuth Server

When building web applications, particularly with frameworks like Angular and backend services powered by Spring Boot, developers often face issues arising from Cross-Origin Resource Sharing (CORS) policies. One common incident is encountering CORS errors when an Angular app attempts to communicate with a Spring Security OAuth-enabled server. In this guide, we'll explore the root of these issues and walk through the steps to resolve them efficiently.

Understanding the Problem

You have an Angular application that integrates with Keycloak for authentication. It generates an access token, which is then added to the Authorization header of your requests using Angular interceptors. On the backend, your application runs with Spring Boot, secured by Spring Security and OAuth2 Resource Server. However, despite correctly configuring the CORS settings in your Spring Boot application, you still receive CORS errors when your Angular app makes HTTP requests to the server running on http://localhost:4200.

Why Do CORS Errors Occur?

CORS errors typically happen when the frontend and backend applications are hosted on different origins (domains, protocols, or ports). The browser restricts cross-origin interactions to protect user data, unless the server explicitly allows it. In your case, the backend should adequately permit requests coming from the Angular frontend.

Steps to Resolve CORS Issues

Initial CORS Configuration

In your Spring Boot application, you tried to enable CORS by creating a separate CorsFilter bean:

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

However, after implementation, the CORS error persisted. This is a common issue where the custom CORS filter is not recognized by Spring Security.

Customizing the Security Configuration

To effectively address the CORS error in your Angular project, you need to customize the Spring Security configuration. Below is the updated code for your SecurityConfig class:

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

Breakdown of the Security Configuration

CORS Customizer:

The corsCustomiser() method is created to ensure that the CorsFilter you defined is acknowledged by the Spring Security.

CORS Configuration Source:

The getCorsConfiguration() method outlines the CORS settings that allow requests from the Angular application on http://localhost:4200. It also specifies allowances for all headers and methods, ensuring a smooth communication process.

Authorize Requests:

The security configuration maintains authorization checks for different HTTP methods, ensuring that access is granted appropriately based on user roles or scopes.

Conclusion

By following the steps outlined above and customizing your Spring Security configuration correctly, you should be able to resolve CORS errors when your Angular application interacts with your Spring Boot server. Remember, CORS can be tricky, but a clear understanding and proper configuration will go a long way in building a seamless application experience.

When debugging similar issues, always check the network console in your browser's developer tools – it can provide insightful error messages that might help you further refine your configuration.

With this thorough approach, you can effectively tackle CORS errors and ensure your applications communicate effortlessly.