Spring boot embedded tomcat application session does not invalidate

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07-10-2024

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Spring Boot Embedded Tomcat Session Invalidation: A Deep Dive

Problem: You're working on a Spring Boot application using an embedded Tomcat server. You expect sessions to expire and invalidate automatically after a certain time, but you find they're persisting longer than expected.

Rephrased: Imagine you're building a website with user logins. You want users to be automatically logged out after a set period of inactivity, but they remain logged in for much longer than you intended. This issue occurs when sessions don't invalidate as expected in your Spring Boot application running on an embedded Tomcat server.

Scenario & Code:

Let's consider a simple Spring Boot application with a controller that displays a welcome message based on the user's session:

@RestController
public class SessionController {

    @GetMapping("/welcome")
    public String welcome(@SessionAttribute(name = "username", required = false) String username) {
        if (username != null) {
            return "Welcome, " + username + "!";
        } else {
            return "Please login.";
        }
    }
}

We define a session timeout in our application.properties file:

server.servlet.session.timeout=10s

This sets the session timeout to 10 seconds. However, when we run the application and access the /welcome endpoint, we find that even after 10 seconds of inactivity, the session remains active.

Insights & Analysis:

The issue arises from the interaction between Spring Boot's @SessionAttribute annotation and embedded Tomcat's session management. While we set the session timeout, the @SessionAttribute annotation fetches session data from a different, internal session manager. This leads to a mismatch, causing the session to persist despite the timeout setting.

Solutions:

1. Use HttpSession: Instead of @SessionAttribute, utilize the HttpSession object to access and manage session data directly. This ensures interaction with the same session object managed by Tomcat.

   @GetMapping("/welcome")
   public String welcome(HttpSession session) {
       String username = (String) session.getAttribute("username");
       if (username != null) {
           return "Welcome, " + username + "!";
       } else {
           return "Please login.";
       }
   }
   

2. Custom Session Timeout: If you need more granular control over session management, consider implementing a custom session timeout mechanism. This could involve using a custom HttpSessionListener to manage session expiration logic.

3. Spring Security: For secure applications, Spring Security provides a robust framework for session management. It offers fine-grained control over session creation, validation, and expiration.

Additional Value & Benefits:

• Improved Security: Ensuring proper session timeout enhances application security by reducing the risk of unauthorized access.
• Resource Optimization: Session expiration frees up resources by automatically releasing session data when inactive.
• User Experience: A well-defined session timeout provides a consistent user experience and helps prevent accidental data loss.

References & Resources:

• Spring Boot Session Management
• Tomcat Session Management
• Spring Security

Conclusion:

Understanding how session management works in Spring Boot with an embedded Tomcat server is crucial for developing robust and secure applications. By using the correct methods for session access and management, developers can ensure sessions expire as expected, leading to better security, resource optimization, and user experience.