application.yaml

##################################################################################
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######### IF YOU FOUND THIS GIST USEFUL, PLEASE LEAVE A STAR. THANKS. ############
##################################################################################
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spring:
  security:
    oauth2:
      client:
        provider:
          <provider-name>:
            issuer-uri: <issuer-uri implementing OIDC>
        registration:
          <provider-name>:
            client-id: <client-id>
            client-secret: <client-secret>
            scope: <comma separated scopes>
            authorization-grant-type: client_credentials
            
OR

spring:
  security:
    oauth2:
      client:
        provider:
          <provider-name>:
            token-uri: <token-uri of provider implementing OIDC>
        registration:
          <provider-name>:
            client-id: <client-id>
            client-secret: <client-secret>
            scope: <comma separated scopes>
            authorization-grant-type: client_credentials

build.gradle

plugins {
	id 'org.springframework.boot' version '2.3.1.RELEASE'
	id 'io.spring.dependency-management' version '1.0.9.RELEASE'
	id 'java'
}
//Relevant dependencies
dependencies {
	implementation 'org.springframework.boot:spring-boot-starter-webflux'
	implementation 'org.springframework.boot:spring-boot-starter-oauth2-client'
}

sample request

webClient.get()
        .uri(<protected resource uri which you want to access>)
        .attributes(clientRegistrationId(<The Provider name specified under registration in app yaml>))
        .retrieve()
        .bodyToMono(String.class)
        .map(string
            -> "Retrieved using Client Credentials Grant Type: " + string)
        .subscribe(LOGGER::info);

Spring WebFlux Security- Client config - OAuth2.0 Client Credentials Flow.md

This gist describes the configuration required for Spring reactive WebClient to make a call to an OAuth2 protected resource through OAuth2.0 Client Credentials Grant Type Flow.

Assumption is that the Authorization Server supports OpenId Connect 1.0 specifications.

websecurityconfiguration.java

@EnableWebFluxSecurity
public class WebSecurityConfiguration {
  @Bean
  public ReactiveOAuth2AuthorizedClientManager authorizedClientManager(
      ReactiveClientRegistrationRepository clientRegistrationRepository,
      ReactiveOAuth2AuthorizedClientService authorizedClientService) {

    ReactiveOAuth2AuthorizedClientProvider authorizedClientProvider =
        ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
            .clientCredentials()
            .build();

    AuthorizedClientServiceReactiveOAuth2AuthorizedClientManager authorizedClientManager =
        new AuthorizedClientServiceReactiveOAuth2AuthorizedClientManager(
            clientRegistrationRepository, authorizedClientService);
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

    return authorizedClientManager;
  }
  @Bean
  public WebClient webClient(ReactiveOAuth2AuthorizedClientManager authorizedClientManager) {
    ServerOAuth2AuthorizedClientExchangeFilterFunction oauth =new ServerOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager);
    return WebClient.builder().filter(oauth).build();
  }
	
  @Bean
  public SecurityWebFilterChain configure(ServerHttpSecurity http) {
	return http
		.oauth2Client()
		.and()
		.build();
  }
}

Thanks so much for this! Really helpful.

Can someone help me with this. it is redirecting to relative URL /authorization/{provider} without going through actual redirect link

Hi do you have an example of Spring Cloud Gateway using the Webflux? I have posted a question here https://stackoverflow.com/questions/67801105/spring-cloud-gateway-with-custom-auth-server-client-credentials-flow-with-webcli

hi , since .oauth2Client() its now actually depracated for Lamabda functions on spring 7 what actually would be the translataion ? or simply would it be obiate it ?