Custom login page in Spring Security 5 using oauth2 returns null - spring

Question

I am developing custom login page in Spring Security 5 using oauth2. So I have customized settings:
#Override
protected void configure(HttpSecurity http) throws Exception {
http
.authorizeRequests().antMatchers("/").permitAll()
.anyRequest().authenticated()
.and()
.oauth2Login().loginPage("/login/oauth2").permitAll();
}
and creating controller with #RequestMapping("/login/oauth2"):
#GetMapping("/")
public String index() {
return "index";
}
#GetMapping("/login/oauth2")
public String login(Model model, OAuth2AuthenticationToken authentication) {
return "login";
}
The login.html page is a regular form which redirect to login method from controller:
<h1>Logowanie</h1>
<a>ZALOGUJ</a>
<a class="btn" href="/login/oauth2/code/google">Login</a>
With this configuration OAuth2AuthenticationToken authentication is null and therefore authentication can't be applied. With default Spring Security 5 configuration everything works fine. The example on which I based is described here: https://docs.spring.io/spring-security/site/docs/5.0.0.RELEASE/reference/htmlsingle/#oauth2login-advanced-login-page; section 31.1 OAuth 2.0 Login Page.

Answer 1

In my app to work I had to create my custom WebMvc configuration:
#Configuration
public class WebMvcConfiguration implements WebMvcConfigurer {
#Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/login").setViewName("login");
registry.setOrder(Ordered.HIGHEST_PRECEDENCE);
}
}
Then in WebSecurityConfig:
#Override
protected void configure(final HttpSecurity http) throws Exception {
http.authorizeRequests().antMatchers("/login").permitAll()
.anyRequest().authenticated()
.and().formLogin()
.loginPage("/login")
.permitAll()
.and().csrf().disable()
.logout().permitAll();
}
I think in this case You don't need custom controller.
I wrote a blog post about silent token refresh in implicit flow, but there You will find full working app with custom login page:
https://regulargeek.blogspot.com/2018/05/angular-5-springboot-2-oauth2-and.html