Angular 4.0 + Spring boot + Spring Security: TemplateInputException: Error resolving template "login" - spring

Question

I am integrating Spring Security in my first Angular project. I followed many articles and examples including this, this, this, this and this. I want my application to have spring security and authenticate from LDAP. If I keep a login.html in \src\main\resources\templates then I can see the login page. But I want the login page to come from Angular component. So I removed/rename the login.html from \src\main\resources\templates. When I hit localhost:8080, it goes to my LoginController (yu=ou can see the sysout in the log), Then I am getting below error
018-04-28 07:30:34.610 DEBUG 11520 --- [nio-8080-exec-9] o.s.s.w.a.i.FilterSecurityInterceptor : RunAsManager did not change Authentication object
2018-04-28 07:30:34.610 DEBUG 11520 --- [nio-8080-exec-9] o.s.security.web.FilterChainProxy : /login reached end of additional filter chain; proceeding with original chain
>>>>>>>>>>>> LoginController.login()...
2018-04-28 07:30:34.611 ERROR 11520 --- [nio-8080-exec-9] org.thymeleaf.TemplateEngine : [THYMELEAF][http-nio-8080-exec-9] Exception processing template "login": Error resolving template "login", template might not exist or might not be accessible by any of the configured Template Resolvers
2018-04-28 07:30:34.611 DEBUG 11520 --- [nio-8080-exec-9] w.c.HttpSessionSecurityContextRepository : SecurityContext is empty or contents are anonymous - context will not be stored in HttpSession.
2018-04-28 07:30:34.611 DEBUG 11520 --- [nio-8080-exec-9] s.s.w.c.SecurityContextPersistenceFilter : SecurityContextHolder now cleared, as request processing completed
2018-04-28 07:30:34.612 ERROR 11520 --- [nio-8080-exec-9] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateInputException: Error resolving template "login", template might not exist or might not be accessible by any of the configured Template Resolvers] with root cause
org.thymeleaf.exceptions.TemplateInputException: Error resolving template "login", template might not exist or might not be accessible by any of the configured Template Resolvers
at org.thymeleaf.TemplateRepository.getTemplate(TemplateRepository.java:246)
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1104)
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1060)
I tried many ways after Googling, but no luck yet. Any suggestion please..
My Files:
LoginController.java
#RequestMapping("/login")
String login(){
System.out.println(">>>>>>>>>>>> LoginController.login()...");
return "login";
}
WebSecurityConfiguration.java
#Override
protected void configure(HttpSecurity http) throws Exception {
http
//.httpBasic().and()
.authorizeRequests()
// .antMatchers("/**").permitAll()
.antMatchers("/index.html", "/", "/home", "/login").permitAll()
.anyRequest().authenticated()
.and().formLogin().loginPage("/login")
.and()
.csrf()
.csrfTokenRepository(CookieCsrfTokenRepository.withHttpOnlyFalse());
/*http
.authorizeRequests()
.antMatchers(HttpMethod.GET, "/resources/**", "/assets/**", "/css/**", "/js/**", "/fonts/**")
//.antMatchers("/**")
.permitAll()
.and()
.authorizeRequests()
.anyRequest()
.authenticated()
.and()
.formLogin()
.loginPage("/login")
.successHandler(authenticationSuccessHandler)
.permitAll()
.and()
.logout()
.logoutUrl("/logout")
.and()
.csrf()
.csrfTokenRepository(CookieCsrfTokenRepository.withHttpOnlyFalse())
.and()
.httpBasic();
//http.cors();
*/ }
app-routing.module.ts
const routes: Routes = [
{ path: 'login', component: LoginComponent },
{ path: '', redirectTo: '/home', pathMatch: 'full' },
{ path: 'dashboard', redirectTo: '/home', pathMatch: 'full' },
{
path: 'home',
component: DashboardComponent,
data: { title: 'Dashboard' }
},
{
path: 'linesidemonitor',
component: LinesideMonitorComponent,
data: {title: 'Lineside Monitor'}
},
If I use .and().formLogin() then I am getting this error:
2018-04-28 08:32:08.394 DEBUG 10404 --- [nio-8080-exec-6] o.s.s.w.a.ExceptionTranslationFilter : Access is denied (user is anonymous); redirecting to authentication entry point
org.springframework.security.access.AccessDeniedException: Access is denied
at org.springframework.security.access.vote.AffirmativeBased.decide(AffirmativeBased.java:84)
at org.springframework.security.access.intercept.AbstractSecurityInterceptor.beforeInvocation(AbstractSecurityInterceptor.java:233)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:124)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91)
If I use .httpBasic().and(), then I am getting browser login popup which I don't want

Answer 1

#SK
The reason you are getting the below exception is you are using Controller and not RestController.
org.thymeleaf.exceptions.TemplateInputException: Error resolving template "login", template might not exist or might not be accessible by any of the configured Template Resolvers
at org.thymeleaf.TemplateRepository.getTemplate(TemplateRepository.java:246)
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1104)
So instead of directly writing the output to browser as JSON, it is doing ViewResolver to resolve the view part of MVC.
Replacing Controller with RestController will make the .formLogin().loginPage("/login") to make the browser request with login, and as it permitted you will get the login page of angular.
httpBasic, it is the nature of browser for pop up as it gets a 401 response code.