Spring Boot: Calling an OAuth2 protected REST service
I have an existing REST API built using Spring Boot. On one of my functions on the service layer, I need to call an external REST service that is protected by OAuth2 (client-credentials).
Using Spring Boot 2.3, I realized OAuth2RestTemplate is deprecated, so I went with using WebClient.
Following this tutorial – https://www.baeldung.com/spring-webclient-oauth2, I now have my WebClientConfig class as follows:
@Configuration class WebClientConfig { @Bean fun webClient( clientRegistrations: ClientRegistrationRepository?, authorizedClients: OAuth2AuthorizedClientRepository?): WebClient? { val oauth2 = ServletOAuth2AuthorizedClientExchangeFilterFunction(clientRegistrations, authorizedClients) oauth2.setDefaultOAuth2AuthorizedClient(false) oauth2.setDefaultClientRegistrationId("test") return WebClient.builder() .apply(oauth2.oauth2Configuration()) .build() } } And in my properties file, I have:
spring: security: oauth2: client: registration: test: client-id: <redacted> client-secret: <redacted> authorization-grant-type: client_credentials provider: test: token-uri: <redacted> I can’t even tell if this is working or not, because I keep getting the following error when accessing a different endpoint on my API that has nothing to do with this OAuth2 authentication:
java.lang.IllegalArgumentException: Invalid Authorization Grant Type (client_credentials) for Client Registration with Id: test I’m at my wits end because I can’t overcome this issue… any help would be very appreciated! Thanks!
This is working for me:
@Bean public WebClient webClient(OAuth2AuthorizedClientManager authorizedClientManager) { ServletOAuth2AuthorizedClientExchangeFilterFunction oauth2Client = new ServletOAuth2AuthorizedClientExchangeFilterFunction( authorizedClientManager); oauth2Client.setDefaultClientRegistrationId("test"); return WebClient.builder() .apply(oauth2Client.oauth2Configuration()) .build(); } @Bean public OAuth2AuthorizedClientManager authorizedClientManager( ClientRegistrationRepository clientRegistrationRepository, OAuth2AuthorizedClientRepository authorizedClientRepository) { OAuth2AuthorizedClientProvider authorizedClientProvider = OAuth2AuthorizedClientProviderBuilder.builder() .refreshToken() .clientCredentials() .build(); DefaultOAuth2AuthorizedClientManager authorizedClientManager = new DefaultOAuth2AuthorizedClientManager( clientRegistrationRepository, authorizedClientRepository); authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider); return authorizedClientManager; } 
