Fix caching error state in ReactiveRemoteJWKSource

oauth2/oauth2-jose/src/main/java/org/springframework/security/oauth2/jwt/ReactiveRemoteJWKSource.java

@@ -43,18 +43,23 @@ class ReactiveRemoteJWKSource implements ReactiveJWKSource {
 	 */
 	private final AtomicReference<Mono<JWKSet>> cachedJWKSet = new AtomicReference<>(Mono.empty());
 
+	/**
+	 * cached url for jwk set.
+	 */
+	private final AtomicReference<String> cachedJwkSetUrl = new AtomicReference<>();
+
 	private WebClient webClient = WebClient.create();
 
-	private final Mono<String> jwkSetURL;
+	private Mono<String> jwkSetURLProvider;
 
 	ReactiveRemoteJWKSource(String jwkSetURL) {
 		Assert.hasText(jwkSetURL, "jwkSetURL cannot be empty");
-		this.jwkSetURL = Mono.just(jwkSetURL);
+		this.cachedJwkSetUrl.set(jwkSetURL);
 	}
 
-	ReactiveRemoteJWKSource(Mono<String> jwkSetURL) {
-		Assert.notNull(jwkSetURL, "jwkSetURL cannot be null");
-		this.jwkSetURL = jwkSetURL.cache();
+	ReactiveRemoteJWKSource(Mono<String> jwkSetURLProvider) {
+		Assert.notNull(jwkSetURLProvider, "jwkSetURLProvider cannot be null");
+		this.jwkSetURLProvider = jwkSetURLProvider;
 	}
 
 	@Override
@@ -100,13 +105,18 @@ private Mono<List<JWK>> get(JWKSelector jwkSelector, JWKSet jwkSet) {
 	 */
 	private Mono<JWKSet> getJWKSet() {
 		// @formatter:off
-		return this.jwkSetURL.flatMap((jwkSetURL) -> this.webClient.get()
-				.uri(jwkSetURL)
-				.retrieve()
-				.bodyToMono(String.class))
+		return Mono.justOrEmpty(this.cachedJwkSetUrl.get())
+				.switchIfEmpty(Mono.defer(() -> this.jwkSetURLProvider
+					.doOnNext(this.cachedJwkSetUrl::set))
+				)
+				.flatMap((jwkSetURL) -> this.webClient.get()
+					.uri(jwkSetURL)
+					.retrieve()
+					.bodyToMono(String.class)
+				)
 				.map(this::parse)
 				.doOnNext((jwkSet) -> this.cachedJWKSet
-						.set(Mono.just(jwkSet))
+					.set(Mono.just(jwkSet))
 				)
 				.cache();
 		// @formatter:on

oauth2/oauth2-jose/src/test/java/org/springframework/security/oauth2/jwt/ReactiveRemoteJWKSourceTests.java

@@ -18,6 +18,7 @@
 
 import java.util.Collections;
 import java.util.List;
+import java.util.function.Supplier;
 
 import com.nimbusds.jose.jwk.JWK;
 import com.nimbusds.jose.jwk.JWKMatcher;
@@ -31,10 +32,15 @@
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.web.reactive.function.client.WebClientResponseException;
+import reactor.core.publisher.Mono;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.doThrow;
 
 /**
  * @author Rob Winch
@@ -52,6 +58,9 @@ public class ReactiveRemoteJWKSourceTests {
 
 	private MockWebServer server;
 
+	@Mock
+	private Supplier<String> mockStringSupplier;
+
 	// @formatter:off
 	private String keys = "{\n"
 			+ "    \"keys\": [\n"
@@ -156,4 +165,18 @@ public void getWhenNoMatchAndKeyIdMatchThenEmpty() {
 		assertThat(this.source.get(this.selector).block()).isEmpty();
 	}
 
+	@Test
+	public void getShouldRecoverAndReturnKeysAfterErrorCase() {
+		given(this.matcher.matches(any())).willReturn(true);
+		this.source = new ReactiveRemoteJWKSource(Mono.fromSupplier(mockStringSupplier));
+		doThrow(WebClientResponseException.ServiceUnavailable.class).when(this.mockStringSupplier).get();
+		// first case: id provider has error state
+		assertThatThrownBy(() -> this.source.get(this.selector).block())
+			.isExactlyInstanceOf(WebClientResponseException.ServiceUnavailable.class);
+		// second case: id provider is healthy again
+		doReturn(this.server.url("/").toString()).when(this.mockStringSupplier).get();
+		var actual = this.source.get(this.selector).block();
+		assertThat(actual).isNotEmpty();
+	}
+
 }