use the applications rest template for the autoconfigured jwks receiver

Author: Michael Kreis

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/resource/servlet/OAuth2ResourceServerJwtConfiguration.java

@@ -19,6 +19,7 @@
 import java.security.interfaces.RSAPublicKey;
 import java.security.spec.X509EncodedKeySpec;
 import java.util.Base64;
+import java.util.Optional;
 
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -37,6 +38,7 @@
 import org.springframework.security.oauth2.jwt.JwtDecoders;
 import org.springframework.security.oauth2.jwt.JwtValidators;
 import org.springframework.security.oauth2.jwt.NimbusJwtDecoder;
+import org.springframework.web.client.RestTemplate;
 
 /**
  * Configures a {@link JwtDecoder} when a JWK Set URI, OpenID Connect Issuer URI or Public
@@ -63,9 +65,14 @@ static class JwtDecoderConfiguration {
 
 		@Bean
 		@ConditionalOnProperty(name = "spring.security.oauth2.resourceserver.jwt.jwk-set-uri")
-		JwtDecoder jwtDecoderByJwkKeySetUri() {
-			NimbusJwtDecoder nimbusJwtDecoder = NimbusJwtDecoder.withJwkSetUri(this.properties.getJwkSetUri())
-					.jwsAlgorithm(SignatureAlgorithm.from(this.properties.getJwsAlgorithm())).build();
+		JwtDecoder jwtDecoderByJwkKeySetUri(Optional<RestTemplate> configuredRestTemplate) {
+			NimbusJwtDecoder.JwkSetUriJwtDecoderBuilder jwtDecoderBuilder = NimbusJwtDecoder
+					.withJwkSetUri(this.properties.getJwkSetUri())
+					.jwsAlgorithm(SignatureAlgorithm.from(this.properties.getJwsAlgorithm()));
+
+			configuredRestTemplate.ifPresent(jwtDecoderBuilder::restOperations);
+			NimbusJwtDecoder nimbusJwtDecoder = jwtDecoderBuilder.build();
+
 			String issuerUri = this.properties.getIssuerUri();
 			if (issuerUri != null) {
 				nimbusJwtDecoder.setJwtValidator(JwtValidators.createDefaultWithIssuer(issuerUri));

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/oauth2/resource/servlet/OAuth2ResourceServerAutoConfigurationTests.java

@@ -54,6 +54,7 @@
 import org.springframework.security.web.FilterChainProxy;
 import org.springframework.security.web.SecurityFilterChain;
 import org.springframework.test.util.ReflectionTestUtils;
+import org.springframework.web.client.RestTemplate;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
@@ -90,6 +91,23 @@ void autoConfigurationShouldConfigureResourceServer() {
 				});
 	}
 
+	@Test
+	void autoConfigurationShouldUseApplicationsRestTemplate() {
+		this.contextRunner
+				.withPropertyValues("spring.security.oauth2.resourceserver.jwt.jwk-set-uri=https://jwk-set-uri.com")
+				.withUserConfiguration(RestTemplateConfig.class).run((context) -> {
+					assertThat(context).hasSingleBean(JwtDecoder.class);
+					JwtDecoder jwtDecoder = context.getBean(JwtDecoder.class);
+					Object processor = ReflectionTestUtils.getField(jwtDecoder, "jwtProcessor");
+					Object keySelector = ReflectionTestUtils.getField(processor, "jwsKeySelector");
+					Object jwkSource = ReflectionTestUtils.getField(keySelector, "jwkSource");
+					Object jwkSetRetriever = ReflectionTestUtils.getField(jwkSource, "jwkSetRetriever");
+					Object restOperations = ReflectionTestUtils.getField(jwkSetRetriever, "restOperations");
+					assertThat(restOperations).isNotNull();
+					assertThat(restOperations).isEqualTo(RestTemplateConfig.configuredRestTemplate);
+				});
+	}
+
 	@Test
 	void autoConfigurationShouldMatchDefaultJwsAlgorithm() {
 		this.contextRunner
@@ -424,6 +442,19 @@ JwtDecoder decoder() {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	@EnableWebSecurity
+	static class RestTemplateConfig {
+
+		private static RestTemplate configuredRestTemplate = new RestTemplate();
+
+		@Bean
+		RestTemplate restTemplate() {
+			return configuredRestTemplate;
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	@EnableWebSecurity
 	static class OpaqueTokenIntrospectorConfig {