Adds support for complex Configurable factory methods.

Adds @configurable to signify that this is a complex config object and use boot binding to create and populate it.

Retry and CircuitBreaker are initially supported.

Adds SimpleFilterSupplier to ease creation of FilterSupplier objects.

Fixes gh-3172

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/common/AbstractGatewayDiscoverer.java

@@ -48,9 +48,12 @@ public <T extends Supplier<Collection<Method>>, R> void doDiscover(Class<T> supp
 			}
 			catch (NoClassDefFoundError e) {
 				if (log.isDebugEnabled()) {
-					log.debug(LogMessage.format("NoClassDefFoundError discovering supplier %s for type %s", supplierClass, returnType));
-				} else if (log.isTraceEnabled()) {
-					log.debug(LogMessage.format("NoClassDefFoundError discovering supplier %s for type %s", supplierClass, returnType), e);
+					log.debug(LogMessage.format("NoClassDefFoundError discovering supplier %s for type %s",
+							supplierClass, returnType));
+				}
+				else if (log.isTraceEnabled()) {
+					log.debug(LogMessage.format("NoClassDefFoundError discovering supplier %s for type %s",
+							supplierClass, returnType), e);
 				}
 			}
 		}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/common/Configurable.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2013-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.gateway.server.mvc.common;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.stereotype.Indexed;
+
+@Target({ ElementType.METHOD })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Indexed
+public @interface Configurable {
+
+	Class<?> value() default Void.class;
+
+}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/config/GatewayMvcPropertiesBeanDefinitionRegistrar.java

@@ -19,6 +19,7 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.atomic.AtomicReference;
@@ -32,20 +33,27 @@
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.boot.context.properties.bind.Bindable;
 import org.springframework.boot.context.properties.bind.Binder;
+import org.springframework.boot.context.properties.bind.handler.IgnoreTopLevelConverterNotFoundBindHandler;
+import org.springframework.boot.context.properties.source.ConfigurationPropertySource;
+import org.springframework.boot.context.properties.source.MapConfigurationPropertySource;
+import org.springframework.cloud.gateway.server.mvc.common.Configurable;
 import org.springframework.cloud.gateway.server.mvc.common.MvcUtils;
 import org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions;
 import org.springframework.cloud.gateway.server.mvc.filter.FilterDiscoverer;
 import org.springframework.cloud.gateway.server.mvc.handler.HandlerDiscoverer;
 import org.springframework.cloud.gateway.server.mvc.invoke.InvocationContext;
 import org.springframework.cloud.gateway.server.mvc.invoke.OperationArgumentResolver;
+import org.springframework.cloud.gateway.server.mvc.invoke.OperationParameter;
 import org.springframework.cloud.gateway.server.mvc.invoke.OperationParameters;
 import org.springframework.cloud.gateway.server.mvc.invoke.ParameterValueMapper;
 import org.springframework.cloud.gateway.server.mvc.invoke.convert.ConversionServiceParameterValueMapper;
 import org.springframework.cloud.gateway.server.mvc.invoke.reflect.OperationMethod;
 import org.springframework.cloud.gateway.server.mvc.invoke.reflect.ReflectiveOperationInvoker;
 import org.springframework.cloud.gateway.server.mvc.predicate.PredicateDiscoverer;
 import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
+import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.core.env.Environment;
 import org.springframework.core.log.LogMessage;
 import org.springframework.core.type.AnnotationMetadata;
@@ -264,6 +272,10 @@ private Optional<NormalizedOperationMethod> findOperation(MultiValueMap<String,
 	private static boolean matchOperation(NormalizedOperationMethod operationMethod, Map<String, String> args) {
 		Map<String, String> normalizedArgs = operationMethod.getNormalizedArgs();
 		OperationParameters parameters = operationMethod.getParameters();
+		if (operationMethod.isConfigurable()) {
+			// this is a special case
+			return true;
+		}
 		if (parameters.getParameterCount() != normalizedArgs.size()) {
 			return false;
 		}
@@ -277,13 +289,37 @@ private static boolean matchOperation(NormalizedOperationMethod operationMethod,
 	}
 
 	private <T> T invokeOperation(OperationMethod operationMethod, Map<String, String> operationArgs) {
-		Map<String, Object> args = new HashMap<>(operationArgs);
+		Map<String, Object> args = new HashMap<>();
+		if (operationMethod.isConfigurable()) {
+			OperationParameter operationParameter = operationMethod.getParameters().get(0);
+			Object config = bindConfigurable(operationMethod, args, operationParameter);
+			args.put(operationParameter.getName(), config);
+		}
+		else {
+			args.putAll(operationArgs);
+		}
 		ReflectiveOperationInvoker operationInvoker = new ReflectiveOperationInvoker(operationMethod,
 				this.parameterValueMapper);
 		InvocationContext context = new InvocationContext(args, trueNullOperationArgumentResolver);
 		return operationInvoker.invoke(context);
 	}
 
+	private static Object bindConfigurable(OperationMethod operationMethod, Map<String, Object> args,
+			OperationParameter operationParameter) {
+		Class<?> configurableType = operationParameter.getType();
+		Configurable configurable = operationMethod.getMethod().getAnnotation(Configurable.class);
+		if (configurable != null && !configurable.value().equals(Void.class)) {
+			configurableType = configurable.value();
+		}
+		Bindable<?> bindable = Bindable.of(configurableType);
+		List<ConfigurationPropertySource> propertySources = Collections
+				.singletonList(new MapConfigurationPropertySource(args));
+		// TODO: potentially deal with conversion service
+		Binder binder = new Binder(propertySources, null, DefaultConversionService.getSharedInstance());
+		Object config = binder.bindOrCreate("", bindable, new IgnoreTopLevelConverterNotFoundBindHandler());
+		return config;
+	}
+
 	static class TrueNullOperationArgumentResolver implements OperationArgumentResolver {
 
 		@Override

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/config/NormalizedOperationMethod.java

@@ -21,6 +21,7 @@
 import java.util.List;
 import java.util.Map;
 
+import org.springframework.cloud.gateway.server.mvc.common.Configurable;
 import org.springframework.cloud.gateway.server.mvc.common.NameUtils;
 import org.springframework.cloud.gateway.server.mvc.common.Shortcut;
 import org.springframework.cloud.gateway.server.mvc.invoke.OperationParameter;
@@ -50,6 +51,11 @@ public Method getMethod() {
 		return delegate.getMethod();
 	}
 
+	public boolean isConfigurable() {
+		Configurable annotation = delegate.getMethod().getAnnotation(Configurable.class);
+		return annotation != null && delegate.getParameters().getParameterCount() == 1;
+	}
+
 	@Override
 	public OperationParameters getParameters() {
 		return delegate.getParameters();

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/Bucket4jFilterFunctions.java

@@ -16,10 +16,7 @@
 
 package org.springframework.cloud.gateway.server.mvc.filter;
 
-import java.lang.reflect.Method;
 import java.time.Duration;
-import java.util.Arrays;
-import java.util.Collection;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
@@ -189,11 +186,10 @@ public RateLimitConfig setHeaderName(String headerName) {
 
 	}
 
-	static class FilterSupplier implements org.springframework.cloud.gateway.server.mvc.filter.FilterSupplier {
+	public static class FilterSupplier extends SimpleFilterSupplier {
 
-		@Override
-		public Collection<Method> get() {
-			return Arrays.asList(Bucket4jFilterFunctions.class.getMethods());
+		public FilterSupplier() {
+			super(Bucket4jFilterFunctions.class);
 		}
 
 	}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/CircuitBreakerFilterFunctions.java

@@ -17,10 +17,8 @@
 package org.springframework.cloud.gateway.server.mvc.filter;
 
 import java.io.IOException;
-import java.lang.reflect.Method;
 import java.net.URI;
 import java.util.Arrays;
-import java.util.Collection;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.Set;
@@ -32,6 +30,7 @@
 
 import org.springframework.cloud.client.circuitbreaker.CircuitBreaker;
 import org.springframework.cloud.client.circuitbreaker.CircuitBreakerFactory;
+import org.springframework.cloud.gateway.server.mvc.common.Configurable;
 import org.springframework.cloud.gateway.server.mvc.common.HttpStatusHolder;
 import org.springframework.cloud.gateway.server.mvc.common.MvcUtils;
 import org.springframework.cloud.gateway.server.mvc.common.Shortcut;
@@ -66,6 +65,12 @@ public static HandlerFilterFunction<ServerResponse, ServerResponse> circuitBreak
 			Consumer<CircuitBreakerConfig> configConsumer) {
 		CircuitBreakerConfig config = new CircuitBreakerConfig();
 		configConsumer.accept(config);
+		return circuitBreaker(config);
+	}
+
+	@Shortcut
+	@Configurable
+	public static HandlerFilterFunction<ServerResponse, ServerResponse> circuitBreaker(CircuitBreakerConfig config) {
 		Set<HttpStatusCode> failureStatuses = config.getStatusCodes().stream()
 				.map(status -> HttpStatusHolder.valueOf(status).resolve()).collect(Collectors.toSet());
 		return (request, next) -> {
@@ -191,11 +196,10 @@ public CircuitBreakerStatusCodeException(HttpStatusCode statusCode) {
 
 	}
 
-	public static class FilterSupplier implements org.springframework.cloud.gateway.server.mvc.filter.FilterSupplier {
+	public static class FilterSupplier extends SimpleFilterSupplier {
 
-		@Override
-		public Collection<Method> get() {
-			return Arrays.asList(CircuitBreakerFilterFunctions.class.getMethods());
+		public FilterSupplier() {
+			super(CircuitBreakerFilterFunctions.class);
 		}
 
 	}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/FilterFunctions.java

@@ -16,10 +16,7 @@
 
 package org.springframework.cloud.gateway.server.mvc.filter;
 
-import java.lang.reflect.Method;
 import java.net.URI;
-import java.util.Arrays;
-import java.util.Collection;
 import java.util.function.Consumer;
 
 import org.springframework.cloud.gateway.server.mvc.common.HttpStatusHolder;
@@ -228,11 +225,10 @@ static HandlerFilterFunction<ServerResponse, ServerResponse> setStatus(HttpStatu
 		return ofResponseProcessor(AfterFilterFunctions.setStatus(statusCode));
 	}
 
-	class FilterSupplier implements org.springframework.cloud.gateway.server.mvc.filter.FilterSupplier {
+	class FilterSupplier extends SimpleFilterSupplier {
 
-		@Override
-		public Collection<Method> get() {
-			return Arrays.asList(FilterFunctions.class.getMethods());
+		public FilterSupplier() {
+			super(FilterFunctions.class);
 		}
 
 	}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/RetryFilterFunctions.java

@@ -26,6 +26,8 @@
 import java.util.concurrent.TimeoutException;
 import java.util.function.Consumer;
 
+import org.springframework.cloud.gateway.server.mvc.common.Configurable;
+import org.springframework.cloud.gateway.server.mvc.common.Shortcut;
 import org.springframework.core.NestedRuntimeException;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
@@ -53,6 +55,12 @@ public static HandlerFilterFunction<ServerResponse, ServerResponse> retry(int re
 	public static HandlerFilterFunction<ServerResponse, ServerResponse> retry(Consumer<RetryConfig> configConsumer) {
 		RetryConfig config = new RetryConfig();
 		configConsumer.accept(config);
+		return retry(config);
+	}
+
+	@Shortcut
+	@Configurable
+	public static HandlerFilterFunction<ServerResponse, ServerResponse> retry(RetryConfig config) {
 		RetryTemplateBuilder retryTemplateBuilder = RetryTemplate.builder();
 		CompositeRetryPolicy compositeRetryPolicy = new CompositeRetryPolicy();
 		Map<Class<? extends Throwable>, Boolean> retryableExceptions = new HashMap<>();
@@ -191,4 +199,12 @@ public ServerResponse getResponse() {
 
 	}
 
+	public static class FilterSupplier extends SimpleFilterSupplier {
+
+		public FilterSupplier() {
+			super(RetryFilterFunctions.class);
+		}
+
+	}
+
 }

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/SimpleFilterSupplier.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2013-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.gateway.server.mvc.filter;
+
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Collection;
+
+public class SimpleFilterSupplier implements FilterSupplier {
+
+	private final Class<?> filtersClass;
+
+	public SimpleFilterSupplier(Class<?> filtersClass) {
+		this.filtersClass = filtersClass;
+	}
+
+	@Override
+	public Collection<Method> get() {
+		return Arrays.asList(filtersClass.getMethods());
+	}
+
+}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/TokenRelayFilterFunctions.java

@@ -16,10 +16,7 @@
 
 package org.springframework.cloud.gateway.server.mvc.filter;
 
-import java.lang.reflect.Method;
 import java.security.Principal;
-import java.util.Arrays;
-import java.util.Collection;
 
 import org.springframework.cloud.gateway.server.mvc.common.Shortcut;
 import org.springframework.security.oauth2.client.OAuth2AuthorizeRequest;
@@ -58,11 +55,10 @@ public static HandlerFilterFunction<ServerResponse, ServerResponse> tokenRelay()
 		};
 	}
 
-	class FilterSupplier implements org.springframework.cloud.gateway.server.mvc.filter.FilterSupplier {
+	public static class FilterSupplier extends SimpleFilterSupplier {
 
-		@Override
-		public Collection<Method> get() {
-			return Arrays.asList(TokenRelayFilterFunctions.class.getMethods());
+		public FilterSupplier() {
+			super(TokenRelayFilterFunctions.class);
 		}
 
 	}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/handler/HandlerFunctions.java

@@ -73,6 +73,10 @@ public static HandlerFunction<ServerResponse> http() {
 		return new LookupProxyExchangeHandlerFunction();
 	}
 
+	public static HandlerFunction<ServerResponse> no() {
+		return http();
+	}
+
 	static class LookupProxyExchangeHandlerFunction implements HandlerFunction<ServerResponse> {
 
 		private final URI uri;

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/invoke/reflect/OperationMethod.java

@@ -26,4 +26,8 @@ public interface OperationMethod {
 
 	OperationParameters getParameters();
 
+	default boolean isConfigurable() {
+		return false;
+	}
+
 }

spring-cloud-gateway-server-mvc/src/main/resources/META-INF/spring.factories

@@ -1,6 +1,7 @@
 org.springframework.cloud.gateway.server.mvc.filter.FilterSupplier=\
   org.springframework.cloud.gateway.server.mvc.filter.Bucket4jFilterFunctions.FilterSupplier,\
   org.springframework.cloud.gateway.server.mvc.filter.CircuitBreakerFilterFunctions.FilterSupplier,\
+  org.springframework.cloud.gateway.server.mvc.filter.RetryFilterFunctions.FilterSupplier,\
   org.springframework.cloud.gateway.server.mvc.filter.TokenRelayFilterFunctions.FilterSupplier,\
   org.springframework.cloud.gateway.server.mvc.filter.FilterFunctions.FilterSupplier