Spring Session and Spring Security

This guide describes how to use Spring Session along with Spring Security. It assumes you have already applied Spring Security to your application.

The completed guide can be found in the security sample application.

1. Updating Dependencies

Before you use Spring Session, you must ensure to update your dependencies. If you are using Maven, ensure to add the following dependencies:

pom.xml

<dependencies>
	<!-- ... -->

	<dependency>
		<groupId>org.springframework.session</groupId>
		<artifactId>spring-session-data-redis</artifactId>
		<version>2.1.0.RELEASE</version>
		<type>pom</type>
	</dependency>
	<dependency>
		<groupId>io.lettuce</groupId>
		<artifactId>lettuce-core</artifactId>
		<version>5.1.1.RELEASE</version>
	</dependency>
	<dependency>
		<groupId>org.springframework</groupId>
		<artifactId>spring-web</artifactId>
		<version>5.1.1.RELEASE</version>
	</dependency>
</dependencies>

2. Spring Configuration

After adding the required dependencies, we can create our Spring configuration. The Spring configuration is responsible for creating a Servlet Filter that replaces the HttpSession implementation with an implementation backed by Spring Session. Add the following Spring Configuration:

@Configuration
@EnableRedisHttpSession (1)
public class Config {

	@Bean
	public LettuceConnectionFactory connectionFactory() {
		return new LettuceConnectionFactory(); (2)
	}
}

1	The `@EnableRedisHttpSession` annotation creates a Spring Bean with the name of `springSessionRepositoryFilter` that implements Filter. The filter is what is in charge of replacing the `HttpSession` implementation to be backed by Spring Session. In this instance Spring Session is backed by Redis.
2	We create a `RedisConnectionFactory` that connects Spring Session to the Redis Server. We configure the connection to connect to localhost on the default port (6379) For more information on configuring Spring Data Redis, refer to the reference documentation.

3. Servlet Container Initialization

Our Spring Configuration created a Spring Bean named springSessionRepositoryFilter that implements Filter. The springSessionRepositoryFilter bean is responsible for replacing the HttpSession with a custom implementation that is backed by Spring Session.

In order for our Filter to do its magic, Spring needs to load our Config class. Since our application is already loading Spring configuration using our SecurityInitializer class, we can simply add our Config class to it.

src/main/java/sample/SecurityInitializer.java

public class SecurityInitializer extends AbstractSecurityWebApplicationInitializer {

	public SecurityInitializer() {
		super(SecurityConfig.class, Config.class);
	}
}

Last we need to ensure that our Servlet Container (i.e. Tomcat) uses our springSessionRepositoryFilter for every request. It is extremely important that Spring Session’s springSessionRepositoryFilter is invoked before Spring Security’s springSecurityFilterChain. This ensures that the HttpSession that Spring Security uses is backed by Spring Session. Fortunately, Spring Session provides a utility class named AbstractHttpSessionApplicationInitializer that makes this extremely easy. You can find an example below:

src/main/java/sample/Initializer.java

public class Initializer extends AbstractHttpSessionApplicationInitializer {

}

The name of our class (Initializer) does not matter. What is important is that we extend AbstractHttpSessionApplicationInitializer.

By extending AbstractHttpSessionApplicationInitializer we ensure that the Spring Bean by the name springSessionRepositoryFilter is registered with our Servlet Container for every request before Spring Security’s springSecurityFilterChain .

4. security Sample Application

4.1. Running the security Sample Application

You can run the sample by obtaining the source code and invoking the following command:

For the sample to work, you must install Redis 2.8+ on localhost and run it with the default port (6379). Alternatively, you can update the RedisConnectionFactory to point to a Redis server. Another option is to use Docker to run Redis on localhost. See Docker Redis repository for detailed instructions.

$ ./gradlew :spring-session-sample-javaconfig-security:tomcatRun

You should now be able to access the application at http://localhost:8080/

4.2. Exploring the security Sample Application

Try using the application. Enter the following to log in:

Username user
Password password

Now click the Login button. You should now see a message indicating your are logged in with the user entered previously. The user’s information is stored in Redis rather than Tomcat’s HttpSession implementation.

4.3. How does it work?

Instead of using Tomcat’s HttpSession, we are actually persisting the values in Redis. Spring Session replaces the HttpSession with an implementation that is backed by Redis. When Spring Security’s SecurityContextPersistenceFilter saves the SecurityContext to the HttpSession it is then persisted into Redis.

When a new HttpSession is created, Spring Session creates a cookie named SESSION in your browser that contains the id of your session. Go ahead and view the cookies (click for help with Chrome or Firefox).

If you like, you can easily remove the session using redis-cli. For example, on a Linux based system you can type:

$ redis-cli keys '*' | xargs redis-cli del

The Redis documentation has instructions for installing redis-cli.

Alternatively, you can also delete the explicit key. Enter the following into your terminal ensuring to replace 7e8383a4-082c-4ffe-a4bc-c40fd3363c5e with the value of your SESSION cookie:

$ redis-cli del spring:session:sessions:7e8383a4-082c-4ffe-a4bc-c40fd3363c5e

Now visit the application at http://localhost:8080/ and observe that we are no longer authenticated.