How to Terminate Request Flow in Spring Cloud API Gateway and Redirect to a Different URL

Learn how to effectively terminate request flow at the Spring Cloud API Gateway level and redirect users to a different route in this handy guide. --- This video is based on the question https://stackoverflow.com/q/66729434/ asked by the user 'Niranga Sandaruwan' ( https://stackoverflow.com/u/3890722/ ) and on the answer https://stackoverflow.com/a/69254884/ provided by the user 'Daniel Ilie' ( https://stackoverflow.com/u/16957555/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to terminate request flow at spring cloud api gateway and redirecting to different URL route Path Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/licensing The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- How to Terminate Request Flow in Spring Cloud API Gateway and Redirect to a Different URL In the world of microservices, APIs serve as the backbone of communication between different services. As applications grow, ensuring secure and efficient request management becomes a priority. When using Spring Cloud Gateway, one common challenge developers face is terminating the request flow and redirecting users if certain conditions are not met. In this guide, we will explore how to effectively handle such scenarios, specifically when a refresh token is missing in an AJAX request. Understanding the Problem Imagine a setup where you have a UI client making AJAX requests to a user microservice through a Spring Cloud Gateway. If the AJAX request does not include a refresh token, you want the flow to stop at the API Gateway and redirect the user to a logout page instead of forwarding the request to the user microservice. Request Flow Example UI Client: http://localhost:8080 Spring Cloud Gateway: http://localhost:8081 User Microservice: http://localhost:8602 (API endpoint: /api/v1/users/bulkUpload) Here’s a brief illustration of the AJAX request being sent from the UI client: [[See Video to Reveal this Text or Code Snippet]] The Requirement If the refresh token is absent from the AJAX request, you want to terminate the request at the API Gateway and redirect the user to the logout page at http://localhost:8080/Logout. The Solution To achieve this, a filter in your Spring Cloud Gateway can be implemented to intercept the requests. Here’s how to effectively configure it: Step 1: Implementing the Gateway Filter Create a filter class that extends AbstractGatewayFilterFactory. In this filter, you will check for the presence of a refresh token and handle the redirection if necessary. Key Code Snippet Here’s the part where you can manage the token check and redirection: [[See Video to Reveal this Text or Code Snippet]] Step 2: Explanation of Key Parts Setting Status Code to FOUND (302): This indicates a temporary redirect, meaning the user should be sent to a different URL. Setting the Location Header: This specifies where the request should be redirected (in this case, to /logout). Completing the Response: response.setComplete() ensures that no further processing is done for the current request, effectively terminating it at the gateway. Full Example of the Filter Here is a broader look at how your filter implementation might look: [[See Video to Reveal this Text or Code Snippet]] Conclusion Managing request flows in a microservice architecture is crucial for ensuring a seamless user experience. By implementing a filter in Spring Cloud Gateway, you can effectively terminate requests and redirect users whenever necessary. This helps in maintaining security and improves the handling of user sessions. By following the outlined steps, you can ensure that your application is resilient and can handle token-based authentication smoothly. Happy coding!