
[[kotlin-config]]
= Kotlin Configuration
Spring Security Kotlin Configuration support has been available since Spring Security 5.3.
It enables users to easily configure Spring Security using a native Kotlin DSL.

NOTE: Spring Security provides https://github.com/spring-projects/spring-security/tree/master/samples/boot/kotlin[a sample applications] which demonstrates the use of Spring Security Kotlin Configuration.

[[kotlin-config-httpsecurity]]
== HttpSecurity

How does Spring Security know that we want to require all users to be authenticated?
How does Spring Security know we want to support form based authentication?
There is a configuration class that is being invoked behind the scenes called `WebSecurityConfigurerAdapter`.
It has a method called `configure` with the following default implementation:

[source,kotlin]
----
fun configure(http: HttpSecurity) {
   http {
        authorizeRequests {
            authorize(anyRequest, authenticated)
        }
       formLogin { }
       httpBasic { }
    }
}
----

The default configuration above:

* Ensures that any request to our application requires the user to be authenticated
* Allows users to authenticate with form based login
* Allows users to authenticate with HTTP Basic authentication

You will notice that this configuration is quite similar the XML Namespace configuration:

[source,xml]
----
<http>
	<intercept-url pattern="/**" access="authenticated"/>
	<form-login />
	<http-basic />
</http>
----

== Multiple HttpSecurity

We can configure multiple HttpSecurity instances just as we can have multiple `<http>` blocks.
The key is to extend the `WebSecurityConfigurerAdapter` multiple times.
For example, the following is an example of having a different configuration for URL's that start with `/api/`.

[source,kotlin]
----
@EnableWebSecurity
class MultiHttpSecurityConfig {
    @Bean                                                            <1>
    public fun userDetailsService(): UserDetailsService {
        val users: User.UserBuilder = User.withDefaultPasswordEncoder()
        val manager = InMemoryUserDetailsManager()
        manager.createUser(users.username("user").password("password").roles("USER").build())
        manager.createUser(users.username("admin").password("password").roles("USER","ADMIN").build())
        return manager
    }

    @Configuration
    @Order(1)                                                        <2>
    class ApiWebSecurityConfigurationAdapter: WebSecurityConfigurerAdapter() {
        override fun configure(http: HttpSecurity) {
            http {
                securityMatcher("/api/**")                           <3>
                authorizeRequests {
                    authorize(anyRequest, hasRole("ADMIN"))
                }
                httpBasic { }
            }
        }
    }

    @Configuration                                                   <4>
    class FormLoginWebSecurityConfigurerAdapter: WebSecurityConfigurerAdapter() {
        override fun configure(http: HttpSecurity) {
            http {
                authorizeRequests {
                    authorize(anyRequest, authenticated)
                }
                formLogin { }
            }
        }
    }
}
----

<1> Configure Authentication as normal
<2> Create an instance of `WebSecurityConfigurerAdapter` that contains `@Order` to specify which `WebSecurityConfigurerAdapter` should be considered first.
<3> The `http.antMatcher` states that this `HttpSecurity` will only be applicable to URLs that start with `/api/`
<4> Create another instance of `WebSecurityConfigurerAdapter`.
If the URL does not start with `/api/` this configuration will be used.
This configuration is considered after `ApiWebSecurityConfigurationAdapter` since it has an `@Order` value after `1` (no `@Order` defaults to last).
