feat: support autoconfigure WeightedServiceInstanceListSupplier (#1163)

docs/src/main/asciidoc/spring-cloud-commons.adoc

@@ -935,7 +935,7 @@ By default, we try to read and parse the weight from the metadata map (the key i
 
 If the weight is not specified in the metadata map, we default the weight of this instance to be 1.
 
-You can use this sample configuration to set it up:
+You can configure it either by setting the value of `spring.cloud.loadbalancer.configurations` to `weighted` or by providing your own `ServiceInstanceListSupplier` bean, for example:
 
 [[weighted-custom-loadbalancer-configuration]]
 [source,java,indent=0]

spring-cloud-loadbalancer/src/main/java/org/springframework/cloud/loadbalancer/annotation/LoadBalancerClientConfiguration.java

@@ -57,6 +57,7 @@ import org.springframework.web.reactive.function.client.WebClient;
  * @author Tim Ysewyn
  * @author BaoLin Zhu
  * @author changjin wei(魏昌进)
+ * @author Zhuozhi Ji
  */
 @Configuration(proxyBeanMethods = false)
 @ConditionalOnDiscoveryEnabled
@@ -133,6 +134,14 @@ public class LoadBalancerClientConfiguration {
 					.build(context);
 		}
 
+		@Bean
+		@ConditionalOnBean(ReactiveDiscoveryClient.class)
+		@ConditionalOnMissingBean
+		@Conditional(WeightedConfigurationCondition.class)
+		public ServiceInstanceListSupplier weightedServiceInstanceListSupplier(ConfigurableApplicationContext context) {
+			return ServiceInstanceListSupplier.builder().withDiscoveryClient().withWeighted().build(context);
+		}
+
 	}
 
 	@Configuration(proxyBeanMethods = false)
@@ -189,6 +198,14 @@ public class LoadBalancerClientConfiguration {
 					.build(context);
 		}
 
+		@Bean
+		@ConditionalOnBean(DiscoveryClient.class)
+		@ConditionalOnMissingBean
+		@Conditional(WeightedConfigurationCondition.class)
+		public ServiceInstanceListSupplier weightedServiceInstanceListSupplier(ConfigurableApplicationContext context) {
+			return ServiceInstanceListSupplier.builder().withBlockingDiscoveryClient().withWeighted().build(context);
+		}
+
 	}
 
 	@Configuration(proxyBeanMethods = false)
@@ -324,4 +341,14 @@ public class LoadBalancerClientConfiguration {
 
 	}
 
+	static class WeightedConfigurationCondition implements Condition {
+
+		@Override
+		public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
+			return LoadBalancerEnvironmentPropertyUtils.equalToForClientOrDefault(context.getEnvironment(),
+					"configurations", "weighted");
+		}
+
+	}
+
 }

spring-cloud-loadbalancer/src/test/java/org/springframework/cloud/loadbalancer/annotation/LoadBalancerClientConfigurationTests.java

@@ -33,6 +33,7 @@ import org.springframework.cloud.loadbalancer.core.HealthCheckServiceInstanceLis
 import org.springframework.cloud.loadbalancer.core.RequestBasedStickySessionServiceInstanceListSupplier;
 import org.springframework.cloud.loadbalancer.core.RetryAwareServiceInstanceListSupplier;
 import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
+import org.springframework.cloud.loadbalancer.core.WeightedServiceInstanceListSupplier;
 import org.springframework.cloud.loadbalancer.core.ZonePreferenceServiceInstanceListSupplier;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -46,6 +47,7 @@ import static org.assertj.core.api.BDDAssertions.then;
  * Tests for {@link LoadBalancerClientConfiguration}.
  *
  * @author Olga Maciaszek-Sharma
+ * @author Zhuozhi Ji
  */
 class LoadBalancerClientConfigurationTests {
 
@@ -113,6 +115,18 @@ class LoadBalancerClientConfigurationTests {
 				});
 	}
 
+	@Test
+	void shouldInstantiateWeightedServiceInstanceListSupplier() {
+		reactiveDiscoveryClientRunner.withUserConfiguration(TestConfig.class)
+				.withPropertyValues("spring.cloud.loadbalancer.configurations=weighted").run(context -> {
+					ServiceInstanceListSupplier supplier = context.getBean(ServiceInstanceListSupplier.class);
+					then(supplier).isInstanceOf(WeightedServiceInstanceListSupplier.class);
+					ServiceInstanceListSupplier delegate = ((DelegatingServiceInstanceListSupplier) supplier)
+							.getDelegate();
+					then(delegate).isInstanceOf(DiscoveryClientServiceInstanceListSupplier.class);
+				});
+	}
+
 	@Test
 	void shouldInstantiateRequestBasedStickySessionServiceInstanceListSupplierTests() {
 		reactiveDiscoveryClientRunner.withUserConfiguration(TestConfig.class)
@@ -182,6 +196,17 @@ class LoadBalancerClientConfigurationTests {
 				});
 	}
 
+	@Test
+	void shouldInstantiateBlockingWeightedServiceInstanceListSupplier() {
+		blockingDiscoveryClientRunner.withUserConfiguration(RestTemplateTestConfig.class)
+				.withPropertyValues("spring.cloud.loadbalancer.configurations=weighted").run(context -> {
+					ServiceInstanceListSupplier supplier = context.getBean(ServiceInstanceListSupplier.class);
+					then(supplier).isInstanceOf(WeightedServiceInstanceListSupplier.class);
+					then(((DelegatingServiceInstanceListSupplier) supplier).getDelegate())
+							.isInstanceOf(DiscoveryClientServiceInstanceListSupplier.class);
+				});
+	}
+
 	@Configuration
 	protected static class TestConfig {