= Session Management Migrations

== Require Explicit Saving of SecurityContextRepository

In Spring Security 5, the default behavior is for the xref:servlet/authentication/architecture.adoc#servlet-authentication-securitycontext[`SecurityContext`] to automatically be saved to the xref:servlet/authentication/persistence.adoc#securitycontextrepository[`SecurityContextRepository`] using the xref:servlet/authentication/persistence.adoc#securitycontextpersistencefilter[`SecurityContextPersistenceFilter`].
Saving must be done just prior to the `HttpServletResponse` being committed and just before `SecurityContextPersistenceFilter`.
Unfortunately, automatic persistence of the `SecurityContext` can surprise users when it is done prior to the request completing (i.e. just prior to committing the `HttpServletResponse`).
It also is complex to keep track of the state to determine if a save is necessary causing unnecessary writes to the `SecurityContextRepository` (i.e. `HttpSession`) at times.

In Spring Security 6, the default behavior is that the xref:servlet/authentication/persistence.adoc#securitycontextholderfilter[`SecurityContextHolderFilter`] will only read the `SecurityContext` from  `SecurityContextRepository` and populate it in the `SecurityContextHolder`.
Users now must explicitly save the `SecurityContext` with the `SecurityContextRepository` if they want the `SecurityContext` to persist between requests.
This removes ambiguity and improves performance by only requiring writing to the `SecurityContextRepository` (i.e. `HttpSession`) when it is necessary.

To opt into the new Spring Security 6 default, the following configuration can be used.

include::partial$servlet/architecture/security-context-explicit.adoc[]

== Change `HttpSessionSecurityContextRepository` to `DelegatingSecurityContextRepository`

In Spring Security 5, the default xref:servlet/authentication/persistence.adoc#securitycontextrepository[`SecurityContextRepository`] is `HttpSessionSecurityContextRepository`.

In Spring Security 6, the default `SecurityContextRepository` is `DelegatingSecurityContextRepository`.
To opt into the new Spring Security 6 default, the following configuration can be used.

.Configure SecurityContextRepository with 6.0 defaults
====
.Java
[source,java,role="primary"]
----
@Bean
public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
	http
		// ...
		.securityContext((securityContext) -> securityContext
			.securityContextRepository(new DelegatingSecurityContextRepository(
				new RequestAttributeSecurityContextRepository(),
				new HttpSessionSecurityContextRepository()
			))
		);
	return http.build();
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
fun securityFilterChain(http: HttpSecurity): SecurityFilterChain {
	http {
		// ...
		securityContext {
			securityContextRepository = DelegatingSecurityContextRepository(
				RequestAttributeSecurityContextRepository(),
				HttpSessionSecurityContextRepository()
			)
		}
	}
	return http.build()
}
----

.XML
[source,xml,role="secondary"]
----
<http security-context-repository-ref="contextRepository">
	<!-- ... -->
</http>
<bean name="contextRepository"
	class="org.springframework.security.web.context.DelegatingSecurityContextRepository">
		<constructor-arg>
			<bean class="org.springframework.security.web.context.RequestAttributeSecurityContextRepository" />
		</constructor-arg>
		<constructor-arg>
			<bean class="org.springframework.security.web.context.HttpSessionSecurityContextRepository" />
		</constructor-arg>
</bean>
----
====

[IMPORTANT]
====
If you are already using an implementation other than `HttpSessionSecurityContextRepository`, you should replace it with your chosen implementation in the example above to ensure that it is used along with `RequestAttributeSecurityContextRepository`.
====

== Address `SecurityContextRepository` Deprecations

In Spring Security 5.7, a new method was added to xref:servlet/authentication/persistence.adoc#securitycontextrepository[`SecurityContextRepository`] with the signature:

    Supplier<SecurityContext> loadContext(HttpServletRequest request)

With the addition of xref:servlet/authentication/persistence.adoc#delegatingsecuritycontextrepository[`DelegatingSecurityContextRepository`] in Spring Security 5.8, that method was deprecated in favor of a new method with the signature:

    DeferredSecurityContext loadDeferredContext(HttpServletRequest request)

In Spring Security 6, the deprecated method was removed.
If you have implemented `SecurityContextRepository` yourself and added an implementation of the `loadContext(request)` method, you can prepare for Spring Security 6 by removing the implementation of that method and implementing the new method instead.

To get started implementing the new method, use the following example to provide a `DeferredSecurityContext`:

.Provide `DeferredSecurityContext`
====
.Java
[source,java,role="primary"]
----
@Override
public DeferredSecurityContext loadDeferredContext(HttpServletRequest request) {
	return new DeferredSecurityContext() {
		private SecurityContext securityContext;
		private boolean isGenerated;

		@Override
		public SecurityContext get() {
			if (this.securityContext == null) {
				this.securityContext = getContextOrNull(request);
				if (this.securityContext == null) {
					SecurityContextHolderStrategy strategy = SecurityContextHolder.getContextHolderStrategy();
					this.securityContext = strategy.createEmptyContext();
					this.isGenerated = true;
				}
			}
			return this.securityContext;
		}

		@Override
		public boolean isGenerated() {
			get();
			return this.isGenerated;
		}
	};
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
override fun loadDeferredContext(request: HttpServletRequest): DeferredSecurityContext {
	return object : DeferredSecurityContext {
		private var securityContext: SecurityContext? = null
		private var isGenerated = false

		override fun get(): SecurityContext {
			if (securityContext == null) {
				securityContext = getContextOrNull(request)
					?: SecurityContextHolder.getContextHolderStrategy().createEmptyContext()
						.also { isGenerated = true }
			}
			return securityContext!!
		}

		override fun isGenerated(): Boolean {
			get()
			return isGenerated
		}
	}
}
----
====

[[requestcache-query-optimization]]
== Optimize Querying of `RequestCache`

In Spring Security 5, the default behavior is to query the xref:servlet/architecture.adoc#savedrequests[saved request] on every request.
This means that in a typical setup, that in order to use the xref:servlet/architecture.adoc#requestcache[`RequestCache`] the `HttpSession` is queried on every request.

In Spring Security 6, the default is that `RequestCache` will only be queried for a cached request if the HTTP parameter `continue` is defined.
This allows Spring Security to avoid unnecessarily reading the `HttpSession` with the `RequestCache`.

In Spring Security 5 the default is to use `HttpSessionRequestCache` which will be queried for a cached request on every request.
If you are not overriding the defaults (i.e. using `NullRequestCache`), then the following configuration can be used to explicitly opt into the Spring Security 6 behavior in Spring Security 5.8:

include::partial$servlet/architecture/request-cache-continue.adoc[]

== Require Explicit Invocation of SessionAuthenticationStrategy

In Spring Security 5, the default configuration relies on `SessionManagementFilter` to detect if a user just authenticated and invoke the `SessionAuthenticationStrategy`.
The problem with this is that it means that in a typical setup, the `HttpSession` must be read for every request.

In Spring Security 6, the default is that authentication mechanisms themselves must invoke the `SessionAuthenticationStrategy`.
This means that there is no need to detect when `Authentication` is done and thus the `HttpSession` does not need to be read for every request.

To opt into the new Spring Security 6 default, the following configuration can be used.

.Require Explicit `SessionAuthenticationStrategy` Invocation
====
.Java
[source,java,role="primary"]
----
@Bean
DefaultSecurityFilterChain springSecurity(HttpSecurity http) throws Exception {
	http
		// ...
		.sessionManagement((sessions) -> sessions
			.requireExplicitAuthenticationStrategy(true)
		);
	return http.build();
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
open fun springSecurity(http: HttpSecurity): SecurityFilterChain {
	http {
		sessionManagement {
			requireExplicitAuthenticationStrategy = true
		}
	}
	return http.build()
}
----

.XML
[source,xml,role="secondary"]
----
<http>
	<!-- ... -->
	<session-management authentication-strategy-explicit-invocation="true"/>
</http>
----
====

If this breaks your application, then you can explicitly opt into the 5.8 defaults using the following configuration:

.Explicit use Spring Security 5.8 defaults for `SessionAuthenticationStrategy`
====
.Java
[source,java,role="primary"]
----
@Bean
DefaultSecurityFilterChain springSecurity(HttpSecurity http) throws Exception {
	http
		// ...
		.sessionManagement((sessions) -> sessions
			.requireExplicitAuthenticationStrategy(false)
		);
	return http.build();
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
open fun springSecurity(http: HttpSecurity): SecurityFilterChain {
	http {
		sessionManagement {
			requireExplicitAuthenticationStrategy = false
		}
	}
	return http.build()
}
----

.XML
[source,xml,role="secondary"]
----
<http>
	<!-- ... -->
	<session-management authentication-strategy-explicit-invocation="false"/>
</http>
----
====
