# Spring Security Integration

Spring Session provides integration with Spring Security.

## Spring Security Remember-me Support

Spring Session provides integration with [Spring Security’s Remember-me Authentication](https://docs.spring.io/spring-security/site/docs/5.6.2/reference/html5/#servlet-rememberme).
The support:

* Changes the session expiration length

* Ensures that the session cookie expires at `Integer.MAX_VALUE`.
  The cookie expiration is set to the largest possible value, because the cookie is set only when the session is created.
  If it were set to the same value as the session expiration, the session would get renewed when the user used it but the cookie expiration would not be updated (causing the expiration to be fixed).

To configure Spring Session with Spring Security in Java Configuration, you can use the following listing as a guide:

```
@Override
protected void configure(HttpSecurity http) throws Exception {
	http
		// ... additional configuration ...
		.rememberMe((rememberMe) -> rememberMe
			.rememberMeServices(rememberMeServices())
		);
}

@Bean
public SpringSessionRememberMeServices rememberMeServices() {
	SpringSessionRememberMeServices rememberMeServices =
			new SpringSessionRememberMeServices();
	// optionally customize
	rememberMeServices.setAlwaysRemember(true);
	return rememberMeServices;
}
```

An XML-based configuration would look something like the following:

```
<security:http>
	<!-- ... -->
	<security:form-login />
	<security:remember-me services-ref="rememberMeServices"/>
</security:http>

<bean id="rememberMeServices"
	class="org.springframework.session.security.web.authentication.SpringSessionRememberMeServices"
	p:alwaysRemember="true"/>
```

## Spring Security Concurrent Session Control

Spring Session provides integration with Spring Security to support its concurrent session control.
This allows limiting the number of active sessions that a single user can have concurrently, but, unlike the default
Spring Security support, this also works in a clustered environment. This is done by providing a custom
implementation of Spring Security’s `SessionRegistry` interface.

When using Spring Security’s Java config DSL, you can configure the custom `SessionRegistry` through the`SessionManagementConfigurer`, as the following listing shows:

```
@Configuration
public class SecurityConfiguration<S extends Session> extends WebSecurityConfigurerAdapter {

	@Autowired
	private FindByIndexNameSessionRepository<S> sessionRepository;

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		// @formatter:off
		http
			// other config goes here...
			.sessionManagement((sessionManagement) -> sessionManagement
				.maximumSessions(2)
				.sessionRegistry(sessionRegistry())
			);
		// @formatter:on
	}

	@Bean
	public SpringSessionBackedSessionRegistry<S> sessionRegistry() {
		return new SpringSessionBackedSessionRegistry<>(this.sessionRepository);
	}

}
```

This assumes that you have also configured Spring Session to provide a `FindByIndexNameSessionRepository` that
returns `Session` instances.

When using XML configuration, it would look something like the following listing:

```
<security:http>
	<!-- other config goes here... -->
	<security:session-management>
		<security:concurrency-control max-sessions="2" session-registry-ref="sessionRegistry"/>
	</security:session-management>
</security:http>

<bean id="sessionRegistry"
	  class="org.springframework.session.security.SpringSessionBackedSessionRegistry">
	<constructor-arg ref="sessionRepository"/>
</bean>
```

This assumes that your Spring Session `SessionRegistry` bean is called `sessionRegistry`, which is the name used by all`SpringHttpSessionConfiguration` subclasses.

## Limitations

Spring Session’s implementation of Spring Security’s `SessionRegistry` interface does not support the `getAllPrincipals`method, as this information cannot be retrieved by using Spring Session. This method is never called by Spring Security,
so this affects only applications that access the `SessionRegistry` themselves.