Add Method Security Preparation Steps

Author: jzheaux

docs/modules/ROOT/nav.adoc

@@ -2,6 +2,7 @@
 * xref:prerequisites.adoc[Prerequisites]
 * xref:community.adoc[Community]
 * xref:whats-new.adoc[What's New]
+* xref:migration.adoc[Migrating for 6.0]
 * xref:getting-spring-security.adoc[Getting Spring Security]
 * xref:features/index.adoc[Features]
 ** xref:features/authentication/index.adoc[Authentication]

docs/modules/ROOT/pages/migration.adoc

@@ -0,0 +1,183 @@
+[[migration]]
+= Migrating to 6.0
+
+The Spring Security team has prepared the 5.8 release to simplify upgrading to Spring Security 6.0.
+Use 5.8 and the steps below to minimize changes when updating to 6.0.
+
+== Servlet
+
+=== Change `@EnableGlobalMethodSecurity` to `@EnableMethodSecurity`
+
+xref:servlet/authorization/method-security.adoc[Method Security] has been xref:servlet/authorization/method-security.adoc#jc-enable-method-security[simplified] through {security-api-url}org/springframework/security/authorization/AuthorizationManager.html[the `AuthorizationManager` API] and direct use of Spring AOP.
+
+The public API difference between these two annotations is that {security-api-url}org/springframework/security/config/annotation/method/configuration/EnableMethodSecurity.html[`@EnableMethodSecurity`] defaults `prePostEnabled` to `true`, while {security-api-url}org/springframework/security/config/annotation/method/configuration/EnableGlobalMethodSecurity.html[`@EnableGlobalMethodSecurity`] defaults it to `false`.
+Also, `@EnableMethodSecurity` internally uses `AuthorizationManager` while `@EnableGlobalMethodSecurity` does not.
+
+This means that the following two listings are functionally equivalent:
+
+====
+.Java
+[source,java,role="primary"]
+----
+@EnableGlobalMethodSecurity(prePostEnabled = true)
+----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+@EnableGlobalMethodSecurity(prePostEnabled = true)
+----
+====
+
+changes to:
+
+====
+.Java
+[source,java,role="primary"]
+----
+@EnableMethodSecurity
+----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+@EnableMethodSecurity
+----
+====
+
+For applications not using `prePostEnabled`, make sure to turn it off to avoid activating unwanted behavior.
+
+For example, a listing like:
+
+====
+.Java
+[source,java,role="primary"]
+----
+@EnableGlobalMethodSecurity(securedEnabled = true)
+----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+@EnableGlobalMethodSecurity(securedEnabled = true)
+----
+====
+
+should change to:
+
+====
+.Java
+[source,java,role="primary"]
+----
+@EnableMethodSecurity(securedEnabled = true, prePostEnabled = false)
+----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+@EnableMethodSecurity(securedEnabled = true, prePostEnabled = false)
+----
+====
+
+Additionally, note that `@EnableMethodSecurity` activates stricter enforcement of Spring Security's non-repeatable or otherwise incompatible annotations.
+If after moving to `@EnableMethodSecurity` you see ``AnnotationConfigurationException``s in your logs, follow the instructions in the exception message to clean up your application's method security annotation usage.
+
+==== Publish your custom `PermissionEvaluator` as a `MethodSecurityExpressionHandler`
+
+`@EnableMethodSecurity` does not pick up a `PermissionEvaluator` bean.
+Instead, it picks up the more generic `MethodSecurityExpressionHandler` to simplify the API.
+
+If you have a custom {security-api-url}org/springframework/security/access/PermissionEvaluator.html[`PermissionEvaluator`] `@Bean`, please change it from:
+
+====
+.Java
+[source,java,role="primary"]
+----
+@Bean
+PermissionEvaluator permissionEvaluator() {
+	// ... your evaluator
+}
+----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+@Bean
+fun permissionEvaluator(): PermissionEvaluator {
+	// ... your evaluator
+}
+----
+====
+
+to:
+
+====
+.Java
+[source,java,role="primary"]
+----
+@Bean
+MethodSecurityExpressionHandler expressionHandler() {
+    var expressionHandler = new DefaultMethodSecurityExpressionHandler();
+    expressionHandler.setPermissionEvaluator(myPermissionEvaluator);
+    return expressionHandler;
+}
+----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+@Bean
+fun expressionHandler(): MethodSecurityExpressionHandler {
+    val expressionHandler = DefaultMethodSecurityExpressionHandler
+    expressionHandler.setPermissionEvaluator(myPermissionEvaluator)
+    return expressionHandler
+}
+----
+====
+
+== Reactive
+
+=== Activate `AuthorizationManager` in `@EnableReactiveMethodSecurity`
+
+xref:reactive/authorization/method.adoc[Method Security] has been xref:reactive/authorization/method.adoc#jc-enable-reactive-method-security-authorization-manager[improved] through {security-api-url}org/springframework/security/authorization/AuthorizationManager.html[the `AuthorizationManager` API] and direct use of Spring AOP.
+
+In Spring Security 5.8, `useAuthorizationManager` was added to {security-api-url}org/springframework/security/config/annotation/method/configuration/EnableReactiveMethodSecurity.html[`@EnableReactiveMethodSecurity`] to allow applications to opt-in to ``AuthorizationManager``'s features.
+
+To opt in, change `useAuthorizationManager` to `true` like so:
+
+====
+.Java
+[source,java,role="primary"]
+----
+@EnableReactiveMethodSecurity
+----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+@EnableReactiveMethodSecurity
+----
+====
+
+changes to:
+
+====
+.Java
+[source,java,role="primary"]
+----
+@EnableReactiveMethodSecurity(useAuthorizationManager = true)
+----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+@EnableReactiveMethodSecurity(useAuthorizationManager = true)
+----
+====
+
+Note that in 6.0, `useAuthorizationManager` defaults to `true`.
+
+Additionally, note that `useAuthorizationManager` activates stricter enforcement of Spring Security's non-repeatable or otherwise incompatible annotations.
+If after turning on `useAuthorizationManager` you see ``AnnotationConfigurationException``s in your logs, follow the instructions in the exception message to clean up your application's method security annotation usage.
+
+