Feign Request Interceptor dynamic values

Question

I'm client of some APIs that I need to send a token in every request, and in order to get this token I need to access /auth/token sending username and password, and thought about using a request interceptor to solve it. But username and password are different per request, there is some way to use dynamic values in feign request interceptor or before every API call I'll need to call /auth/token using a normal feign client?

I have a Service that access this token API

@Service
@RequiredArgsConstructor
public class AuthService {
  private final AuthClient client;
  private final AuthProperties properties;

  @Cacheable("tokens")
  public AuthToken getToken(AuthUser user) {
      return client.authenticate(properties.getClientId(), properties.getSecret(), user.getUser(),
            user.getPassword());
  }
}

A feign client to access the token API

public interface AuthClient {
  @RequestLine("GET /token?client_id={client_id}&client_secret={client_secret}&grant_type=password&username={username}&password={password}")
  AuthToken authenticate(@Param("client_id") String client_id, @Param("client_secret") String client_secret,
                            @Param("username") String username, @Param("password") String password);
}

And a RequestInterceptor that uses this service

@RequiredArgsConstructor
public class AuthRequestInterceptor implements RequestInterceptor {

  private final AuthUser user;
  @Autowired
  private final AuthService authService;

  @Override
  public void apply(RequestTemplate template) {
    AuthToken token = authService.getToken(user);
    template.header("Authorization", "Bearer " + token.getAccess_token());
  }
}

I'm not sure how to add this interceptor when building the feign client to set the user per request

Answer 1

When using Spring, you will need to register the RequestInterceptor as a @Bean to have it automatically applied. If you are not using Spring, or manually building Feign Clients, register the interceptor using the Feign.builder.interceptor() method.