403 response with Request Interceptors Feing client - spring-boot

Question

I have a request interceptor config for my feign client that i will like to verify if it is configured properly. It is suppose to make request to the auth url and get a authorization taken.
This seems to work fine. But i think its not putting it to every request sent to to the resource server. Hence i keep getting 403. but when i try this on postman with the auth token generated in my code it works fine.
Bellow is the code
#Component
public class FeignC2aSystemOAuthInterceptor implements RequestInterceptor {
#Value("${c2a.oauth2.clientId}")
private String clientId;
#Value("${c2a_system.authUrl}")
private String authUrl;
#Value("${c2a.oauth2.clientSecret}")
private String clientSecret;
private String jwt;
private LocalDateTime expirationDate = LocalDateTime.now();
private final RestTemplate restTemplate;
public FeignC2aSystemOAuthInterceptor(RestTemplate restTemplate) {
this.restTemplate = restTemplate;
}
#Override
public void apply(RequestTemplate requestTemplate) {
if (LocalDateTime.now().isAfter(expirationDate)) {
requestToken();
System.out.println("JUST AFTER REQUEST" + this.jwt);
}
/* use the token */
System.out.println("USE THE TOKEN" + this.jwt);
requestTemplate.header("Authorization: Bearer " + this.jwt);
}
private void requestToken() {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
MultiValueMap<String, String> map = new LinkedMultiValueMap<String, String>();
map.add("client_id", clientId);
map.add("client_secret", clientSecret);
map.add("grant_type", "client_credentials");
HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<MultiValueMap<String, String>>(map, headers);
ResponseEntity<C2AAuthResponse> response = restTemplate.postForEntity(authUrl, request, C2AAuthResponse.class);
this.jwt = Objects.requireNonNull(response.getBody()).getAccessToken();
LocalDateTime localDateTime = LocalDateTime.now();
this.expirationDate = localDateTime.plusSeconds(response.getBody().getExpiresIn());
}
config
#Configuration
public class FeignC2aSystemConfig {
#Bean
RestTemplate getRestTemplate() {
return new RestTemplate();
};
#Bean
FeignC2aSystemOAuthInterceptor fen () {
return new FeignC2aSystemOAuthInterceptor(getRestTemplate());
}
#Bean
Logger.Level feignLoggerLevel() {
return Logger.Level.FULL;
}
}
and client
#FeignClient(name = "c2aSystem", url = "${c2a_system.base_url}", configuration = FeignC2aSystemConfig.class)
public interface C2AApiClient {
#PostMapping(value = C2ASystemIntegrationUrls.SEND, produces = "application/json", consumes = "application/json")
HttpServletResponse sendSms(#RequestBody C2aMessage c2aMessage);
#GetMapping(value = C2ASystemIntegrationUrls.GETLIST, produces = "application/json", consumes = "application/json")
List<MessageData> getMessages();
}
during logging i have noticed that it i call the interceptor and i can see the auth token logged using sout.
Please i would like to know if i have made a mess somewhere along the way that might cause it not to apply the authorization token to the request, thanks

Answer 1

You're using the RequestTemplate API wrong in this line:
requestTemplate.header("Authorization: Bearer " + this.jwt);
the header method accepts 2 parameters. First a key and then the corresponding value, and there's an overload with a String vararg. Your code will complile because of the varag parameter but won't work because it'll be handled as an empty array argument.
The implementation in the RequestTemplate is clear. If the array is empty, it'll consider that header for removal.
The fix is easy, just put the JWT token into the second argument instead of concatenating it with the header key, like this:
requestTemplate.header("Authorization: Bearer ", this.jwt);