Authorized Client Features

This section covers additional features provided by Spring Security for OAuth2 Client.

Resolving an Authorized Client

The @RegisteredOAuth2AuthorizedClient annotation provides the capability of resolving a method parameter to an argument value of type OAuth2AuthorizedClient. This is a convenient alternative compared to accessing the OAuth2AuthorizedClient using the ReactiveOAuth2AuthorizedClientManager or ReactiveOAuth2AuthorizedClientService.

Java
Kotlin

@Controller
public class OAuth2ClientController {

	@GetMapping("/")
	public Mono<String> index(@RegisteredOAuth2AuthorizedClient("okta") OAuth2AuthorizedClient authorizedClient) {
		return Mono.just(authorizedClient.getAccessToken())
				...
				.thenReturn("index");
	}
}

@Controller
class OAuth2ClientController {
    @GetMapping("/")
    fun index(@RegisteredOAuth2AuthorizedClient("okta") authorizedClient: OAuth2AuthorizedClient): Mono<String> {
        return Mono.just(authorizedClient.accessToken)
                ...
                .thenReturn("index")
    }
}

The @RegisteredOAuth2AuthorizedClient annotation is handled by OAuth2AuthorizedClientArgumentResolver, which directly uses a ReactiveOAuth2AuthorizedClientManager and therefore inherits it’s capabilities.

WebClient integration for Reactive Environments

The OAuth 2.0 Client support integrates with WebClient using an ExchangeFilterFunction.

The ServerOAuth2AuthorizedClientExchangeFilterFunction provides a simple mechanism for requesting protected resources by using an OAuth2AuthorizedClient and including the associated OAuth2AccessToken as a Bearer Token. It directly uses an ReactiveOAuth2AuthorizedClientManager and therefore inherits the following capabilities:

An OAuth2AccessToken will be requested if the client has not yet been authorized.
- authorization_code - triggers the Authorization Request redirect to initiate the flow
- client_credentials - the access token is obtained directly from the Token Endpoint
- password - the access token is obtained directly from the Token Endpoint
If the OAuth2AccessToken is expired, it will be refreshed (or renewed) if a ReactiveOAuth2AuthorizedClientProvider is available to perform the authorization

The following code shows an example of how to configure WebClient with OAuth 2.0 Client support:

Java
Kotlin

@Bean
WebClient webClient(ReactiveOAuth2AuthorizedClientManager authorizedClientManager) {
	ServerOAuth2AuthorizedClientExchangeFilterFunction oauth2Client =
			new ServerOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager);
	return WebClient.builder()
			.filter(oauth2Client)
			.build();
}

@Bean
fun webClient(authorizedClientManager: ReactiveOAuth2AuthorizedClientManager): WebClient {
    val oauth2Client = ServerOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager)
    return WebClient.builder()
            .filter(oauth2Client)
            .build()
}

Providing the Authorized Client

The ServerOAuth2AuthorizedClientExchangeFilterFunction determines the client to use (for a request) by resolving the OAuth2AuthorizedClient from the ClientRequest.attributes() (request attributes).

The following code shows how to set an OAuth2AuthorizedClient as a request attribute:

Java
Kotlin

@GetMapping("/")
public Mono<String> index(@RegisteredOAuth2AuthorizedClient("okta") OAuth2AuthorizedClient authorizedClient) {
	String resourceUri = ...

	return webClient
			.get()
			.uri(resourceUri)
			.attributes(oauth2AuthorizedClient(authorizedClient))   (1)
			.retrieve()
			.bodyToMono(String.class)
			...
			.thenReturn("index");
}

@GetMapping("/")
fun index(@RegisteredOAuth2AuthorizedClient("okta") authorizedClient: OAuth2AuthorizedClient): Mono<String> {
    val resourceUri: String = ...

    return webClient
            .get()
            .uri(resourceUri)
            .attributes(oauth2AuthorizedClient(authorizedClient)) (1)
            .retrieve()
            .bodyToMono<String>()
            ...
            .thenReturn("index")
}

1	`oauth2AuthorizedClient()` is a `static` method in `ServerOAuth2AuthorizedClientExchangeFilterFunction`.

The following code shows how to set the ClientRegistration.getRegistrationId() as a request attribute:

Java
Kotlin

@GetMapping("/")
public Mono<String> index() {
	String resourceUri = ...

	return webClient
			.get()
			.uri(resourceUri)
			.attributes(clientRegistrationId("okta"))   (1)
			.retrieve()
			.bodyToMono(String.class)
			...
			.thenReturn("index");
}

@GetMapping("/")
fun index(): Mono<String> {
    val resourceUri: String = ...

    return webClient
            .get()
            .uri(resourceUri)
            .attributes(clientRegistrationId("okta"))  (1)
            .retrieve()
            .bodyToMono<String>()
            ...
            .thenReturn("index")
}

1	`clientRegistrationId()` is a `static` method in `ServerOAuth2AuthorizedClientExchangeFilterFunction`.

Defaulting the Authorized Client

If neither OAuth2AuthorizedClient or ClientRegistration.getRegistrationId() is provided as a request attribute, the ServerOAuth2AuthorizedClientExchangeFilterFunction can determine the default client to use depending on it’s configuration.

If setDefaultOAuth2AuthorizedClient(true) is configured and the user has authenticated using ServerHttpSecurity.oauth2Login(), the OAuth2AccessToken associated with the current OAuth2AuthenticationToken is used.

The following code shows the specific configuration:

Java
Kotlin

@Bean
WebClient webClient(ReactiveOAuth2AuthorizedClientManager authorizedClientManager) {
	ServerOAuth2AuthorizedClientExchangeFilterFunction oauth2Client =
			new ServerOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager);
	oauth2Client.setDefaultOAuth2AuthorizedClient(true);
	return WebClient.builder()
			.filter(oauth2Client)
			.build();
}

@Bean
fun webClient(authorizedClientManager: ReactiveOAuth2AuthorizedClientManager): WebClient {
    val oauth2Client = ServerOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager)
    oauth2Client.setDefaultOAuth2AuthorizedClient(true)
    return WebClient.builder()
            .filter(oauth2Client)
            .build()
}

It is recommended to be cautious with this feature since all HTTP requests will receive the access token.

Alternatively, if setDefaultClientRegistrationId("okta") is configured with a valid ClientRegistration, the OAuth2AccessToken associated with the OAuth2AuthorizedClient is used.

The following code shows the specific configuration:

Java
Kotlin

@Bean
WebClient webClient(ReactiveOAuth2AuthorizedClientManager authorizedClientManager) {
	ServerOAuth2AuthorizedClientExchangeFilterFunction oauth2Client =
			new ServerOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager);
	oauth2Client.setDefaultClientRegistrationId("okta");
	return WebClient.builder()
			.filter(oauth2Client)
			.build();
}

@Bean
fun webClient(authorizedClientManager: ReactiveOAuth2AuthorizedClientManager): WebClient {
    val oauth2Client = ServerOAuth2AuthorizedClientExchangeFilterFunction(authorizedClientManager)
    oauth2Client.setDefaultClientRegistrationId("okta")
    return WebClient.builder()
            .filter(oauth2Client)
            .build()
}

It is recommended to be cautious with this feature since all HTTP requests will receive the access token.