Spring Security - when get login page, security try to authenticate and return 401 error

I am developing Spring boot application with microservices architecture. I am using JWT authentication.

1-http://localhost:8762/auth {"username":"admin", "password":"12345"} (POST request)

2-http://localhost:8762/auth/loginPage (GET request for page)

When i try first request, authentication is working well and i get login info and jwt token. But when i try second request for getting login page, spring is trying to authenticate and returns 401 error.

How can i ignore authentication for login page.

I have zull project as gateway and authentication project as auth.

if(header == null || !header.startsWith(jwtConfig.getPrefix())) {
            chain.doFilter(request, response);          // If not valid, go to the next filter.
            return;
        }

I think at this point, i have to override filter. But i don't know how i write filter.

Here is my code for authentication.

auth project -> WebSecurityConfigurerAdapter

@EnableWebSecurity
public class SecurityCredentialsConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private JwtConfig jwtConfig;
    
    @Autowired
    private UserDetailsService userDetailsService;
    
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .csrf().disable()
             // make sure we use stateless session; session won't be used to store user's state.
            .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS)
            .and()
                // handle an authorized attempts 
            .exceptionHandling().authenticationEntryPoint((req, rsp, e) -> rsp.sendError(HttpServletResponse.SC_UNAUTHORIZED))
            .and()
            // Add a filter to validate user credentials and add token in the response header
            
            // What's the authenticationManager()? 
            // An object provided by WebSecurityConfigurerAdapter, used to authenticate the user passing user's credentials
            // The filter needs this auth manager to authenticate the user.
            .addFilter(new JwtUsernameAndPasswordAuthenticationFilter(authenticationManager(), jwtConfig()))    
            .authorizeRequests()
            // allow all POST requests 
            .antMatchers("/auth/**").permitAll()
            .antMatchers("/user/register").permitAll()
            // any other requests must be authenticated
            .anyRequest().authenticated()
              .and()
              .formLogin()
              .loginPage("/auth/loginPage");
    }
    
    // Spring has UserDetailsService interface, which can be overriden to provide our implementation for fetching user from database (or any other source).
    // The UserDetailsService object is used by the auth manager to load the user from database.
    // In addition, we need to define the password encoder also. So, auth manager can compare and verify passwords.
    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.userDetailsService(userDetailsService).passwordEncoder(new BCryptPasswordEncoder());
    }
    
    @Bean
    public JwtConfig jwtConfig() {
        return new JwtConfig();
    }
}

auth -> UsernamePasswordAuthenticationFilter

public class JwtUsernameAndPasswordAuthenticationFilter extends UsernamePasswordAuthenticationFilter {

    
        private AuthenticationManager authManager;
        
        private final JwtConfig jwtConfig;
        
        public JwtUsernameAndPasswordAuthenticationFilter(AuthenticationManager authManager, JwtConfig jwtConfig) {
            this.authManager = authManager;
            this.jwtConfig = jwtConfig;
            
            // By default, UsernamePasswordAuthenticationFilter listens to "/login" path. 
            // In our case, we use "/auth". So, we need to override the defaults.
            //this.setRequiresAuthenticationRequestMatcher(new AntPathRequestMatcher(jwtConfig.getUri(), "POST"));

            this.setRequiresAuthenticationRequestMatcher(new OrRequestMatcher(                                                                                     
                    new AntPathRequestMatcher("/auth/**")
                    , new AntPathRequestMatcher("/user/register")
            ));
        }
        
        @Override
        public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response)
                throws AuthenticationException {
            
            try {
                
                // 1. Get credentials from request
                UserDTO creds = new ObjectMapper().readValue(request.getInputStream(), UserDTO.class);
                
                // 2. Create auth object (contains credentials) which will be used by auth manager
                UsernamePasswordAuthenticationToken authToken = new UsernamePasswordAuthenticationToken(
                        creds.getUsername(), creds.getPassword(), Collections.emptyList());
                
                // 3. Authentication manager authenticate the user, and use UserDetialsServiceImpl::loadUserByUsername() method to load the user.
                return authManager.authenticate(authToken);
                
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        
        // Upon successful authentication, generate a token.
        // The 'auth' passed to successfulAuthentication() is the current authenticated user.
        @Override
        protected void successfulAuthentication(HttpServletRequest request, HttpServletResponse response, FilterChain chain,
                Authentication auth) throws IOException, ServletException {
            Long now = System.currentTimeMillis();
            String token = Jwts.builder()
                .setSubject(auth.getName()) 
                // Convert to list of strings. 
                // This is important because it affects the way we get them back in the Gateway.
                .claim("authorities", auth.getAuthorities().stream()
                    .map(GrantedAuthority::getAuthority).collect(Collectors.toList()))
                .setIssuedAt(new Date(now))
                .setExpiration(new Date(now + jwtConfig.getExpiration() * 1000))  // in milliseconds
                .signWith(SignatureAlgorithm.HS512, jwtConfig.getSecret().getBytes())
                .compact();
            
            // Add token to header
            response.addHeader(jwtConfig.getHeader(), jwtConfig.getPrefix() + token);
        }
}

Controller

@GetMapping("/auth/loginPage")
    public String loginPage() {
        return "login";
    }