= Web Migrations

== Favor Relative URIs

When redirecting to a login endpoint, Spring Security has favored absolute URIs in the past.
For example, if you set your login page like so:

[tabs]
======
Java::
+
[source,java,role="primary"]
----
http
    // ...
    .formLogin((form) -> form.loginPage("/my-login"))
    // ...
----

Kotlin::
+
[source,kotlin,role="secondary"]
----
http {
    formLogin {
        loginPage = "/my-login"
    }
}
----

Xml::
+
[source,kotlin,role="secondary"]
----
<http ...>
    <form-login login-page="/my-login"/>
</http>
----
======

then when redirecting to `/my-login` Spring Security would use a `Location:` like the following:

[source]
----
302 Found
// ...
Location: https://myapp.example.org/my-login
----

However, this is no longer necessary given that the RFC is was based on is now obsolete.

In Spring Security 7, this is changed to use a relative URI like so:

[source]
----
302 Found
// ...
Location: /my-login
----

Most applications will not notice a difference.
However, in the event that this change causes problems, you can switch back to the Spring Security 6 behavior by setting the `favorRelativeUrls` value:

[tabs]
======
Java::
+
[source,java,role="primary"]
----
LoginUrlAuthenticationEntryPoint entryPoint = new LoginUrlAuthenticationEntryPoint("/my-login");
entryPoint.setFavorRelativeUris(false);
http
    // ...
    .exceptionHandling((exceptions) -> exceptions.authenticaitonEntryPoint(entryPoint))
    // ...
----

Kotlin::
+
[source,kotlin,role="secondary"]
----
LoginUrlAuthenticationEntryPoint entryPoint = LoginUrlAuthenticationEntryPoint("/my-login")
entryPoint.setFavorRelativeUris(false)

http {
    exceptionHandling {
        authenticationEntryPoint = entryPoint
    }
}
----

Xml::
+
[source,kotlin,role="secondary"]
----
<http entry-point-ref="myEntryPoint">
    <!-- ... -->
</http>

<b:bean id="myEntryPoint" class="org.springframework.security.web.authentication.LoginUrlAuthenticationEntryPoint">
    <b:property name="favorRelativeUris" value="true"/>
</b:bean>
----
======
