Micrometer Support (#462)

Setting up micrometer for Feign, fixes #457
This makes spring-cloud-openfeign capable of configuring any Capability (e.g.: Metrics5Capability for Dropwizard Metrics or MicrometerCapability for micrometer). This also auto-configures MicrometerCapability if a MeterRegistry is available and feign-micrometer is on the classpath.

docs/src/main/asciidoc/_configprops.adoc

@@ -21,6 +21,7 @@
 |feign.httpclient.max-connections-per-route | `50` | 
 |feign.httpclient.time-to-live | `900` | 
 |feign.httpclient.time-to-live-unit |  | 
+|feign.metrics.enabled | `true` | Enables metrics capability for Feign.
 |feign.okhttp.enabled | `false` | Enables the use of the OK HTTP Client by Feign.
 
 |===

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

@@ -32,9 +32,9 @@ Example spring boot app
 @EnableFeignClients
 public class Application {
 
-    public static void main(String[] args) {
-        SpringApplication.run(Application.class, args);
-    }
+	public static void main(String[] args) {
+		SpringApplication.run(Application.class, args);
+	}
 
 }
 ----
@@ -44,14 +44,14 @@ public class Application {
 ----
 @FeignClient("stores")
 public interface StoreClient {
-    @RequestMapping(method = RequestMethod.GET, value = "/stores")
-    List<Store> getStores();
+	@RequestMapping(method = RequestMethod.GET, value = "/stores")
+	List<Store> getStores();
 
-    @RequestMapping(method = RequestMethod.GET, value = "/stores")
-    Page<Store> getStores(Pageable pageable);
+	@RequestMapping(method = RequestMethod.GET, value = "/stores")
+	Page<Store> getStores(Pageable pageable);
 
-    @RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json")
-    Store update(@PathVariable("storeId") Long storeId, Store store);
+	@RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json")
+	Store update(@PathVariable("storeId") Long storeId, Store store);
 }
 ----
 
@@ -65,7 +65,7 @@ of the `@FeignClient` annotation.
 The load-balancer client above will want to discover the physical addresses
 for the "stores" service. If your application is a Eureka client then
 it will resolve the service in the Eureka service registry. If you
-don't want to use Eureka, you can simply configure a list of servers
+don't want to use Eureka, you can configure a list of servers
 in your external configuration using https://cloud.spring.io/spring-cloud-static/spring-cloud-commons/current/reference/html/#simplediscoveryclient[`SimpleDiscoveryClient`].
 
 Spring Cloud OpenFeign supports all the features available for the blocking mode of Spring Cloud LoadBalancer. You can read more about them in the https://docs.spring.io/spring-cloud-commons/docs/current/reference/html/#spring-cloud-loadbalancer[project documentation].
@@ -84,7 +84,7 @@ Spring Cloud lets you take full control of the feign client by declaring additio
 ----
 @FeignClient(name = "stores", configuration = FooConfiguration.class)
 public interface StoreClient {
-    //..
+	//..
 }
 ----
 
@@ -104,7 +104,7 @@ Placeholders are supported in the `name` and `url` attributes.
 ----
 @FeignClient(name = "${feign.name}", url = "${feign.url}")
 public interface StoreClient {
-    //..
+	//..
 }
 ----
 
@@ -113,10 +113,11 @@ Spring Cloud OpenFeign provides the following beans by default for feign (`BeanT
 * `Decoder` feignDecoder: `ResponseEntityDecoder` (which wraps a `SpringDecoder`)
 * `Encoder` feignEncoder: `SpringEncoder`
 * `Logger` feignLogger: `Slf4jLogger`
+* `MicrometerCapability` micrometerCapability: If `feign-micrometer` is on the classpath and `MeterRegistry` is available
 * `Contract` feignContract: `SpringMvcContract`
 * `Feign.Builder` feignBuilder: `FeignCircuitBreaker.Builder`
-* `Client` feignClient: if Spring Cloud LoadBalancer is in the classpath, `FeignBlockingLoadBalancerClient` is used.
-If none of them is in the classpath, the default feign client is used.
+* `Client` feignClient: If Spring Cloud LoadBalancer is on the classpath, `FeignBlockingLoadBalancerClient` is used.
+If none of them is on the classpath, the default feign client is used.
 
 NOTE: `spring-cloud-starter-openfeign` supports `spring-cloud-starter-loadbalancer`. However, as is an optional dependency, you need to make sure it been added to your project if you want to use it.
 
@@ -132,6 +133,7 @@ Spring Cloud OpenFeign _does not_ provide the following beans by default for fei
 * `Collection<RequestInterceptor>`
 * `SetterFactory`
 * `QueryMapEncoder`
+* `Capability` (`MicrometerCapability` is provided by default)
 
 A bean of `Retryer.NEVER_RETRY` with the type `Retryer` is created by default, which will disable retrying.
 Notice this retrying behavior is different from the Feign default one, where it will automatically retry IOExceptions,
@@ -143,15 +145,15 @@ Creating a bean of one of those type and placing it in a `@FeignClient` configur
 ----
 @Configuration
 public class FooConfiguration {
-    @Bean
-    public Contract feignContract() {
-        return new feign.Contract.Default();
-    }
+	@Bean
+	public Contract feignContract() {
+		return new feign.Contract.Default();
+	}
 
-    @Bean
-    public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
-        return new BasicAuthRequestInterceptor("user", "password");
-    }
+	@Bean
+	public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
+		return new BasicAuthRequestInterceptor("user", "password");
+	}
 }
 ----
 
@@ -163,25 +165,29 @@ application.yml
 [source,yaml]
 ----
 feign:
-  client:
-    config:
-      feignName:
-        connectTimeout: 5000
-        readTimeout: 5000
-        loggerLevel: full
-        errorDecoder: com.example.SimpleErrorDecoder
-        retryer: com.example.SimpleRetryer
-       defaultQueryParameters:
-          query: queryValue
-        defaultRequestHeaders:
-          header: headerValue
-        requestInterceptors:
-          - com.example.FooRequestInterceptor
-          - com.example.BarRequestInterceptor
-        decode404: false
-        encoder: com.example.SimpleEncoder
-        decoder: com.example.SimpleDecoder
-        contract: com.example.SimpleContract
+	client:
+		config:
+			feignName:
+				connectTimeout: 5000
+				readTimeout: 5000
+				loggerLevel: full
+				errorDecoder: com.example.SimpleErrorDecoder
+				retryer: com.example.SimpleRetryer
+				defaultQueryParameters:
+					query: queryValue
+				defaultRequestHeaders:
+					header: headerValue
+				requestInterceptors:
+					- com.example.FooRequestInterceptor
+					- com.example.BarRequestInterceptor
+				decode404: false
+				encoder: com.example.SimpleEncoder
+				decoder: com.example.SimpleDecoder
+				contract: com.example.SimpleContract
+				capabilities:
+					- com.example.FooCapability
+					- com.example.BarCapability
+				metrics.enabled: false
 ----
 
 Default configurations can be specified in the `@EnableFeignClients` attribute `defaultConfiguration` in a similar manner as described above. The difference is that this configuration will apply to _all_ feign clients.
@@ -194,12 +200,12 @@ application.yml
 [source,yaml]
 ----
 feign:
-  client:
-    config:
-      default:
-        connectTimeout: 5000
-        readTimeout: 5000
-        loggerLevel: basic
+	client:
+		config:
+			default:
+				connectTimeout: 5000
+				readTimeout: 5000
+				loggerLevel: basic
 ----
 
 If we create both `@Configuration` bean and configuration properties, configuration properties will win.
@@ -215,7 +221,7 @@ collision of these configuration beans.
 ----
 @FeignClient(contextId = "fooClient", name = "stores", configuration = FooConfiguration.class)
 public interface FooClient {
-    //..
+	//..
 }
 ----
 
@@ -223,7 +229,7 @@ public interface FooClient {
 ----
 @FeignClient(contextId = "barClient", name = "stores", configuration = BarConfiguration.class)
 public interface BarClient {
-    //..
+	//..
 }
 ----
 
@@ -279,12 +285,13 @@ class FooController {
 
 	private FooClient adminClient;
 
-    	@Autowired
-	public FooController(Decoder decoder, Encoder encoder, Client client, Contract contract) {
+	@Autowired
+	public FooController(Client client, Encoder encoder, Decoder decoder, Contract contract, MicrometerCapability micrometerCapability) {
 		this.fooClient = Feign.builder().client(client)
 				.encoder(encoder)
 				.decoder(decoder)
 				.contract(contract)
+				.addCapability(micrometerCapability)
 				.requestInterceptor(new BasicAuthRequestInterceptor("user", "user"))
 				.target(FooClient.class, "https://PROD-SVC");
 
@@ -292,9 +299,10 @@ class FooController {
 				.encoder(encoder)
 				.decoder(decoder)
 				.contract(contract)
+				.addCapability(micrometerCapability)
 				.requestInterceptor(new BasicAuthRequestInterceptor("admin", "admin"))
 				.target(FooClient.class, "https://PROD-SVC");
-    }
+	}
 }
 ----
 
@@ -321,7 +329,7 @@ To disable Spring Cloud CircuitBreaker support on a per-client basis create a va
 ----
 @Configuration
 public class FooConfiguration {
-    	@Bean
+	@Bean
 	@Scope("prototype")
 	public Feign.Builder feignBuilder() {
 		return Feign.builder();
@@ -371,8 +379,8 @@ This allows grouping common operations into convenient base interfaces.
 ----
 public interface UserService {
 
-    @RequestMapping(method = RequestMethod.GET, value ="/users/{id}")
-    User getUser(@PathVariable("id") long id);
+	@RequestMapping(method = RequestMethod.GET, value ="/users/{id}")
+	User getUser(@PathVariable("id") long id);
 }
 ----
 
@@ -455,10 +463,63 @@ For example, the following would set the `Logger.Level` to `FULL`:
 ----
 @Configuration
 public class FooConfiguration {
-    @Bean
-    Logger.Level feignLoggerLevel() {
-        return Logger.Level.FULL;
-    }
+	@Bean
+	Logger.Level feignLoggerLevel() {
+		return Logger.Level.FULL;
+	}
+}
+----
+
+=== Feign Capability support
+
+The Feign capabilities expose core Feign components so that these components can be modified. For example, the capabilities can take the `Client`, _decorate_ it, and give the decorated instance back to Feign.
+The support for metrics libraries is a good real-life example for this. See <<feign-metrics>>.
+
+Creating one or more `Capability` beans and placing them in a `@FeignClient` configuration lets you register them and modify the behavior of the involved client.
+
+[source,java,indent=0]
+----
+@Configuration
+public class FooConfiguration {
+	@Bean
+	Capability customCapability() {
+		return new CustomCapability();
+	}
+}
+----
+
+=== Feign metrics
+
+If all of the following conditions are true, a `MicrometerCapability` bean is created and registered so that your Feign client publishes metrics to Micrometer:
+
+* `feign-micrometer` is on the classpath
+* A `MeterRegistry` bean is available
+* feign metrics properties are set to `true` (by default)
+	- `feign.metrics.enabled=true` (for all clients)
+	- `feign.client.config.feignName.metrics.enabled=true` (for a single client)
+
+NOTE: If your application already uses Micrometer, enabling metrics is as simple as putting `feign-micrometer` onto your classpath.
+
+You can also disable the feature by either:
+
+* excluding `feign-micrometer` from your classpath
+* setting one of the feign metrics properties to `false`
+	- `feign.metrics.enabled=false`
+	- `feign.client.config.feignName.metrics.enabled=false`
+
+NOTE: `feign.metrics.enabled=false` disables metrics support for *all* Feign clients regardless of the value of the client-level flags: `feign.client.config.feignName.metrics.enabled`.
+If you want to enable or disable merics per client, don't set `feign.metrics.enabled` and use `feign.client.config.feignName.metrics.enabled`.
+
+You can also customize the `MicrometerCapability` by registering your own bean:
+
+[source,java,indent=0]
+----
+@Configuration
+public class FooConfiguration {
+	@Bean
+	public MicrometerCapability micrometerCapability(MeterRegistry meterRegistry) {
+		return new MicrometerCapability(meterRegistry);
+	}
 }
 ----
 
@@ -477,10 +538,10 @@ For example, the `Params` class defines parameters `param1` and `param2`:
 ----
 // Params.java
 public class Params {
-    private String param1;
-    private String param2;
+	private String param1;
+	private String param2;
 
-    // [Getters and setters omitted for brevity]
+	// [Getters and setters omitted for brevity]
 }
 ----
 
@@ -491,8 +552,8 @@ The following feign client uses the `Params` class by using the `@SpringQueryMap
 @FeignClient("demo")
 public interface DemoTemplate {
 
-    @GetMapping(path = "/demo")
-    String demoEndpoint(@SpringQueryMap Params params);
+	@GetMapping(path = "/demo")
+	String demoEndpoint(@SpringQueryMap Params params);
 }
 ----
 
@@ -513,8 +574,8 @@ and deserialize HATEOAS representation models: https://docs.spring.io/spring-hat
 @FeignClient("demo")
 public interface DemoTemplate {
 
-    @GetMapping(path = "/stores")
-    CollectionModel<Store> getStores();
+	@GetMapping(path = "/stores")
+	CollectionModel<Store> getStores();
 }
 ----
 
@@ -543,8 +604,8 @@ Note that both variable name and the path segment placeholder are called `matrix
 @FeignClient("demo")
 public interface DemoTemplate {
 
-    @GetMapping(path = "/stores")
-    CollectionModel<Store> getStores();
+	@GetMapping(path = "/stores")
+	CollectionModel<Store> getStores();
 }
 ----
 

spring-cloud-openfeign-core/pom.xml

@@ -99,6 +99,11 @@
 			<artifactId>feign-slf4j</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>io.github.openfeign</groupId>
+			<artifactId>feign-micrometer</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>io.github.openfeign</groupId>
 			<artifactId>feign-httpclient</artifactId>

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignClientFactoryBean.java

@@ -22,6 +22,7 @@ import java.util.Map;
 import java.util.Objects;
 import java.util.concurrent.TimeUnit;
 
+import feign.Capability;
 import feign.Client;
 import feign.Contract;
 import feign.ExceptionPropagationPolicy;
@@ -60,6 +61,7 @@ import org.springframework.util.StringUtils;
  * @author Olga Maciaszek-Sharma
  * @author Ilia Ilinykh
  * @author Marcin Grzejszczak
+ * @author Jonatan Ivanov
  */
 public class FeignClientFactoryBean
 		implements FactoryBean<Object>, InitializingBean, ApplicationContextAware, BeanFactoryAware {
@@ -199,6 +201,12 @@ public class FeignClientFactoryBean
 		if (exceptionPropagationPolicy != null) {
 			builder.exceptionPropagationPolicy(exceptionPropagationPolicy);
 		}
+
+		Map<String, Capability> capabilities = getInheritedAwareInstances(context, Capability.class);
+		if (capabilities != null) {
+			capabilities.values().stream().sorted(AnnotationAwareOrderComparator.INSTANCE)
+					.forEach(builder::addCapability);
+		}
 	}
 
 	protected void configureUsingProperties(FeignClientProperties.FeignClientConfiguration config,
@@ -264,6 +272,10 @@ public class FeignClientFactoryBean
 		if (Objects.nonNull(config.getExceptionPropagationPolicy())) {
 			builder.exceptionPropagationPolicy(config.getExceptionPropagationPolicy());
 		}
+
+		if (config.getCapabilities() != null) {
+			config.getCapabilities().stream().map(this::getOrInstantiate).forEach(builder::addCapability);
+		}
 	}
 
 	private <T> T getOrInstantiate(Class<T> tClass) {

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignClientMetricsEnabledCondition.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2021-2021 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.openfeign;
+
+import java.util.Map;
+
+import org.springframework.context.annotation.Condition;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.core.type.AnnotatedTypeMetadata;
+
+/**
+ * @author Jonatan Ivanov
+ */
+class FeignClientMetricsEnabledCondition implements Condition {
+
+	@Override
+	public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
+		FeignClientProperties feignClientProperties = context.getBeanFactory()
+				.getBeanProvider(FeignClientProperties.class).getIfAvailable();
+		if (feignClientProperties != null) {
+			Map<String, FeignClientProperties.FeignClientConfiguration> feignClientConfigMap = feignClientProperties
+					.getConfig();
+			if (feignClientConfigMap != null) {
+				FeignClientProperties.FeignClientConfiguration feignClientConfig = feignClientConfigMap
+						.get(context.getEnvironment().getProperty("feign.client.name"));
+				if (feignClientConfig != null) {
+					FeignClientProperties.MetricsProperties metrics = feignClientConfig.getMetrics();
+					if (metrics != null && metrics.getEnabled() != null) {
+						return metrics.getEnabled();
+					}
+				}
+			}
+		}
+
+		return true;
+	}
+
+}

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignClientProperties.java

@@ -22,6 +22,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
+import feign.Capability;
 import feign.Contract;
 import feign.ExceptionPropagationPolicy;
 import feign.Logger;
@@ -37,6 +38,7 @@ import org.springframework.boot.context.properties.ConfigurationProperties;
  * @author Eko Kurniawan Khannedy
  * @author Ilia Ilinykh
  * @author Ram Anaswara
+ * @author Jonatan Ivanov
  */
 @ConfigurationProperties("feign.client")
 public class FeignClientProperties {
@@ -134,6 +136,10 @@ public class FeignClientProperties {
 
 		private ExceptionPropagationPolicy exceptionPropagationPolicy;
 
+		private List<Class<Capability>> capabilities;
+
+		private MetricsProperties metrics;
+
 		public Logger.Level getLoggerLevel() {
 			return loggerLevel;
 		}
@@ -238,6 +244,22 @@ public class FeignClientProperties {
 			this.exceptionPropagationPolicy = exceptionPropagationPolicy;
 		}
 
+		public List<Class<Capability>> getCapabilities() {
+			return capabilities;
+		}
+
+		public void setCapabilities(List<Class<Capability>> capabilities) {
+			this.capabilities = capabilities;
+		}
+
+		public MetricsProperties getMetrics() {
+			return metrics;
+		}
+
+		public void setMetrics(MetricsProperties metrics) {
+			this.metrics = metrics;
+		}
+
 		@Override
 		public boolean equals(Object o) {
 			if (this == o) {
@@ -255,14 +277,50 @@ public class FeignClientProperties {
 					&& Objects.equals(decoder, that.decoder) && Objects.equals(contract, that.contract)
 					&& Objects.equals(exceptionPropagationPolicy, that.exceptionPropagationPolicy)
 					&& Objects.equals(defaultRequestHeaders, that.defaultRequestHeaders)
-					&& Objects.equals(defaultQueryParameters, that.defaultQueryParameters);
+					&& Objects.equals(defaultQueryParameters, that.defaultQueryParameters)
+					&& Objects.equals(capabilities, that.capabilities) && Objects.equals(metrics, that.metrics);
 		}
 
 		@Override
 		public int hashCode() {
 			return Objects.hash(loggerLevel, connectTimeout, readTimeout, retryer, errorDecoder, requestInterceptors,
 					decode404, encoder, decoder, contract, exceptionPropagationPolicy, defaultQueryParameters,
-					defaultRequestHeaders);
+					defaultRequestHeaders, capabilities, metrics);
+		}
+
+	}
+
+	/**
+	 * Metrics configuration for Feign Client.
+	 */
+	public static class MetricsProperties {
+
+		private Boolean enabled = true;
+
+		public Boolean getEnabled() {
+			return enabled;
+		}
+
+		public void setEnabled(Boolean enabled) {
+			this.enabled = enabled;
+		}
+
+		@Override
+		public boolean equals(Object o) {
+			if (this == o) {
+				return true;
+			}
+			if (o == null || getClass() != o.getClass()) {
+				return false;
+			}
+
+			MetricsProperties that = (MetricsProperties) o;
+			return Objects.equals(enabled, that.enabled);
+		}
+
+		@Override
+		public int hashCode() {
+			return Objects.hash(enabled);
 		}
 
 	}

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignClientsConfiguration.java

@@ -27,7 +27,9 @@ import feign.codec.Decoder;
 import feign.codec.Encoder;
 import feign.form.MultipartFormContentProcessor;
 import feign.form.spring.SpringFormEncoder;
+import feign.micrometer.MicrometerCapability;
 import feign.optionals.OptionalDecoder;
+import io.micrometer.core.instrument.MeterRegistry;
 
 import org.springframework.beans.factory.ObjectFactory;
 import org.springframework.beans.factory.ObjectProvider;
@@ -62,6 +64,7 @@ import static feign.form.ContentType.MULTIPART;
  * @author Dave Syer
  * @author Venil Noronha
  * @author Darren Foong
+ * @author Jonatan Ivanov
  */
 @Configuration(proxyBeanMethods = false)
 public class FeignClientsConfiguration {
@@ -203,4 +206,19 @@ public class FeignClientsConfiguration {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnBean(type = "io.micrometer.core.instrument.MeterRegistry")
+	@ConditionalOnClass(name = "feign.micrometer.MicrometerCapability")
+	@ConditionalOnProperty(name = "feign.metrics.enabled", matchIfMissing = true)
+	@Conditional(FeignClientMetricsEnabledCondition.class)
+	protected static class MetricsConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean
+		public MicrometerCapability micrometerCapability(MeterRegistry meterRegistry) {
+			return new MicrometerCapability(meterRegistry);
+		}
+
+	}
+
 }

spring-cloud-openfeign-core/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -43,6 +43,12 @@
 			"type": "java.lang.Boolean",
 			"description": "Enables the request sent by Feign to be compressed.",
 			"defaultValue": "false"
+		},
+		{
+			"name": "feign.metrics.enabled",
+			"type": "java.lang.Boolean",
+			"description": "Enables metrics capability for Feign.",
+			"defaultValue": "true"
 		}
 	]
 }

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientConfigurationTests.java

@@ -0,0 +1,140 @@
+/*
+ * Copyright 2021-2021 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.openfeign;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+import feign.Capability;
+import feign.Contract;
+import feign.ExceptionPropagationPolicy;
+import feign.Logger;
+import feign.RequestInterceptor;
+import feign.Retryer;
+import feign.codec.Decoder;
+import feign.codec.Encoder;
+import feign.codec.ErrorDecoder;
+import org.assertj.core.util.Lists;
+import org.assertj.core.util.Maps;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsAndHashCodeConsistency;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsConsistency;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsReflexivity;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsSymmetricity;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsTransitivity;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertHashCodeConsistency;
+
+/**
+ * @author Jonatan Ivanov
+ */
+class FeignClientConfigurationTests {
+
+	@Test
+	void shouldDefaultToValuesWhenFieldsNotSet() {
+		FeignClientProperties.FeignClientConfiguration config = new FeignClientProperties.FeignClientConfiguration();
+
+		assertThat(config.getLoggerLevel()).isNull();
+		assertThat(config.getConnectTimeout()).isNull();
+		assertThat(config.getReadTimeout()).isNull();
+		assertThat(config.getRetryer()).isNull();
+		assertThat(config.getErrorDecoder()).isNull();
+		assertThat(config.getRequestInterceptors()).isNull();
+		assertThat(config.getDefaultRequestHeaders()).isNull();
+		assertThat(config.getDefaultQueryParameters()).isNull();
+		assertThat(config.getDecode404()).isNull();
+		assertThat(config.getDecoder()).isNull();
+		assertThat(config.getEncoder()).isNull();
+		assertThat(config.getContract()).isNull();
+		assertThat(config.getExceptionPropagationPolicy()).isNull();
+		assertThat(config.getCapabilities()).isNull();
+		assertThat(config.getMetrics()).isNull();
+	}
+
+	@Test
+	void shouldReturnValuesWhenSet() {
+		FeignClientProperties.FeignClientConfiguration config = new FeignClientProperties.FeignClientConfiguration();
+		config.setLoggerLevel(Logger.Level.FULL);
+		config.setConnectTimeout(21);
+		config.setReadTimeout(42);
+		config.setRetryer(Retryer.class);
+		config.setErrorDecoder(ErrorDecoder.class);
+		List<Class<RequestInterceptor>> requestInterceptors = Lists.list(RequestInterceptor.class);
+		config.setRequestInterceptors(requestInterceptors);
+		Map<String, Collection<String>> defaultRequestHeaders = Maps.newHashMap("default", Lists.emptyList());
+		config.setDefaultRequestHeaders(defaultRequestHeaders);
+		Map<String, Collection<String>> defaultQueryParameters = Maps.newHashMap("default", Lists.emptyList());
+		config.setDefaultQueryParameters(defaultQueryParameters);
+		config.setDecode404(true);
+		config.setDecoder(Decoder.class);
+		config.setEncoder(Encoder.class);
+		config.setContract(Contract.class);
+		config.setExceptionPropagationPolicy(ExceptionPropagationPolicy.UNWRAP);
+		List<Class<Capability>> capabilities = Lists.list(Capability.class);
+		config.setCapabilities(capabilities);
+		FeignClientProperties.MetricsProperties metrics = new FeignClientProperties.MetricsProperties();
+		config.setMetrics(metrics);
+
+		assertThat(config.getLoggerLevel()).isSameAs(Logger.Level.FULL);
+		assertThat(config.getConnectTimeout()).isEqualTo(21);
+		assertThat(config.getReadTimeout()).isEqualTo(42);
+		assertThat(config.getRetryer()).isSameAs(Retryer.class);
+		assertThat(config.getErrorDecoder()).isSameAs(ErrorDecoder.class);
+		assertThat(config.getRequestInterceptors()).isSameAs(requestInterceptors);
+		assertThat(config.getDefaultRequestHeaders()).isSameAs(defaultRequestHeaders);
+		assertThat(config.getDefaultQueryParameters()).isSameAs(defaultQueryParameters);
+		assertThat(config.getDecode404()).isTrue();
+		assertThat(config.getDecoder()).isSameAs(Decoder.class);
+		assertThat(config.getEncoder()).isSameAs(Encoder.class);
+		assertThat(config.getContract()).isSameAs(Contract.class);
+		assertThat(config.getExceptionPropagationPolicy()).isSameAs(ExceptionPropagationPolicy.UNWRAP);
+		assertThat(config.getCapabilities()).isSameAs(capabilities);
+		assertThat(config.getMetrics()).isSameAs(metrics);
+	}
+
+	/**
+	 * Sanity-checks equals and hashCode contracts but does not check every variation of
+	 * the fields.
+	 */
+	@Test
+	void shouldHaveSomewhatValidEqualsAndHashCode() {
+		FeignClientProperties.FeignClientConfiguration configOne = new FeignClientProperties.FeignClientConfiguration();
+		FeignClientProperties.FeignClientConfiguration configTwo = new FeignClientProperties.FeignClientConfiguration();
+		FeignClientProperties.FeignClientConfiguration configThree = new FeignClientProperties.FeignClientConfiguration();
+		FeignClientProperties.FeignClientConfiguration differentConfig = new FeignClientProperties.FeignClientConfiguration();
+		differentConfig.setDecode404(true);
+
+		assertEqualsReflexivity(configOne);
+
+		assertEqualsSymmetricity(configOne, configTwo);
+		assertEqualsSymmetricity(configOne, differentConfig);
+		assertEqualsSymmetricity(configOne, 42);
+
+		assertEqualsTransitivity(configOne, configTwo, configThree);
+
+		assertEqualsConsistency(configOne, configTwo);
+		assertEqualsConsistency(configOne, differentConfig);
+		assertEqualsConsistency(configOne, 42);
+		assertEqualsConsistency(configOne, null);
+
+		assertHashCodeConsistency(configOne);
+		assertEqualsAndHashCodeConsistency(configOne, configTwo);
+	}
+
+}

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientDisabledClientLevelFeaturesTests.java

@@ -0,0 +1,121 @@
+/*
+ * Copyright 2021-2021 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.openfeign;
+
+import java.util.Map;
+
+import feign.Capability;
+import feign.Contract;
+import feign.RequestLine;
+import feign.micrometer.MicrometerCapability;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Jonatan Ivanov
+ */
+@DirtiesContext
+@ActiveProfiles("no-foo-metrics")
+@SpringBootTest(classes = FeignClientDisabledClientLevelFeaturesTests.TestConfiguration.class)
+class FeignClientDisabledClientLevelFeaturesTests {
+
+	@Autowired
+	private FeignContext context;
+
+	@Autowired
+	private FooClient foo;
+
+	@Autowired
+	private BarClient bar;
+
+	@Test
+	void clientsAvailable() {
+		assertThat(foo).isNotNull();
+		assertThat(bar).isNotNull();
+	}
+
+	@Test
+	void capabilitiesShouldNotBeAvailableWhenDisabled() {
+		assertThat(context.getInstance("foo", MicrometerCapability.class)).isNull();
+		assertThat(context.getInstances("foo", Capability.class)).isEmpty();
+
+		assertThat(context.getInstance("bar", MicrometerCapability.class)).isNotNull();
+		Map<String, Capability> barCapabilities = context.getInstances("bar", Capability.class);
+		assertThat(barCapabilities).hasSize(2);
+		assertThat(barCapabilities.get("micrometerCapability")).isExactlyInstanceOf(MicrometerCapability.class);
+		assertThat(barCapabilities.get("noOpCapability")).isExactlyInstanceOf(NoOpCapability.class);
+	}
+
+	@FeignClient(name = "foo", url = "https://foo", configuration = FooConfiguration.class)
+	interface FooClient {
+
+		@RequestLine("GET /")
+		String get();
+
+	}
+
+	@FeignClient(name = "bar", url = "https://bar", configuration = BarConfiguration.class)
+	interface BarClient {
+
+		@RequestMapping(value = "/", method = RequestMethod.GET)
+		String get();
+
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	@EnableAutoConfiguration
+	@EnableConfigurationProperties(FeignClientProperties.class)
+	@EnableFeignClients(clients = { FooClient.class, BarClient.class })
+	protected static class TestConfiguration {
+
+	}
+
+	public static class FooConfiguration {
+
+		@Bean // if the feign configuration empty, the context is not able to start
+		public Contract feignContract() {
+			return new Contract.Default();
+		}
+
+	}
+
+	public static class BarConfiguration {
+
+		@Bean
+		public Capability noOpCapability() {
+			return new NoOpCapability();
+		}
+
+	}
+
+	private static class NoOpCapability implements Capability {
+
+	}
+
+}

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientDisabledFeaturesTests.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2021-2021 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.openfeign;
+
+import java.util.Map;
+
+import feign.Capability;
+import feign.Contract;
+import feign.RequestLine;
+import feign.micrometer.MicrometerCapability;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Jonatan Ivanov
+ */
+@DirtiesContext
+@ActiveProfiles("no-metrics")
+@SpringBootTest(classes = FeignClientDisabledFeaturesTests.TestConfiguration.class)
+class FeignClientDisabledFeaturesTests {
+
+	@Autowired
+	private FeignContext context;
+
+	@Autowired
+	private FooClient foo;
+
+	@Autowired
+	private BarClient bar;
+
+	@Test
+	void clientsAvailable() {
+		assertThat(foo).isNotNull();
+		assertThat(bar).isNotNull();
+	}
+
+	@Test
+	void capabilitiesShouldNotBeAvailable() {
+		assertThat(context.getInstance("foo", MicrometerCapability.class)).isNull();
+		assertThat(context.getInstances("foo", Capability.class)).isEmpty();
+
+		assertThat(context.getInstance("bar", MicrometerCapability.class)).isNull();
+		Map<String, Capability> barCapabilities = context.getInstances("bar", Capability.class);
+		assertThat(barCapabilities).hasSize(1);
+		assertThat(barCapabilities.get("noOpCapability")).isExactlyInstanceOf(NoOpCapability.class);
+	}
+
+	@FeignClient(name = "foo", url = "https://foo", configuration = FooConfiguration.class)
+	interface FooClient {
+
+		@RequestLine("GET /")
+		String get();
+
+	}
+
+	@FeignClient(name = "bar", url = "https://bar", configuration = BarConfiguration.class)
+	interface BarClient {
+
+		@RequestMapping(value = "/", method = RequestMethod.GET)
+		String get();
+
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	@EnableAutoConfiguration
+	@EnableConfigurationProperties(FeignClientProperties.class)
+	@EnableFeignClients(clients = { FooClient.class, BarClient.class })
+	protected static class TestConfiguration {
+
+	}
+
+	public static class FooConfiguration {
+
+		@Bean // if the feign configuration empty, the context is not able to start
+		public Contract feignContract() {
+			return new Contract.Default();
+		}
+
+	}
+
+	public static class BarConfiguration {
+
+		@Bean
+		public Capability noOpCapability() {
+			return new NoOpCapability();
+		}
+
+	}
+
+	private static class NoOpCapability implements Capability {
+
+	}
+
+}

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientErrorDecoderTests.java

@@ -44,6 +44,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author Michael Cramer
+ * @author Jonatan Ivanov
  */
 @RunWith(SpringJUnit4ClassRunner.class)
 @SpringBootTest(classes = FeignClientErrorDecoderTests.TestConfiguration.class)
@@ -85,7 +86,8 @@ public class FeignClientErrorDecoderTests {
 
 	@SuppressWarnings({ "unchecked", "ConstantConditions" })
 	private Object getErrorDecoderFromClient(final Object client) {
-		Object invocationHandler = ReflectionTestUtils.getField(client, "h");
+		Object invocationHandlerLambda = ReflectionTestUtils.getField(client, "h");
+		Object invocationHandler = ReflectionTestUtils.getField(invocationHandlerLambda, "arg$2");
 		Map<Method, InvocationHandlerFactory.MethodHandler> dispatch = (Map<Method, InvocationHandlerFactory.MethodHandler>) ReflectionTestUtils
 				.getField(invocationHandler, "dispatch");
 		Method key = new ArrayList<>(dispatch.keySet()).get(0);

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientMetricsEnabledConditionTests.java

@@ -0,0 +1,225 @@
+/*
+ * Copyright 2021-2021 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.openfeign;
+
+import java.util.HashMap;
+
+import org.assertj.core.util.Maps;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.core.env.Environment;
+import org.springframework.core.type.AnnotatedTypeMetadata;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+/**
+ * @author Jonatan Ivanov
+ */
+@ExtendWith({ MockitoExtension.class })
+class FeignClientMetricsEnabledConditionTests {
+
+	@Mock
+	private ConditionContext context;
+
+	@Mock
+	private AnnotatedTypeMetadata metadata;
+
+	@Mock
+	private ConfigurableListableBeanFactory beanFactory;
+
+	@Mock
+	private ObjectProvider<FeignClientProperties> beanProvider;
+
+	@Mock
+	private Environment environment;
+
+	private final FeignClientMetricsEnabledCondition condition = new FeignClientMetricsEnabledCondition();
+
+	@BeforeEach
+	void setUp() {
+		when(context.getBeanFactory()).thenReturn(beanFactory);
+		when(beanFactory.getBeanProvider(FeignClientProperties.class)).thenReturn(beanProvider);
+	}
+
+	@AfterEach
+	void tearDown() {
+		verify(context).getBeanFactory();
+		verify(beanFactory).getBeanProvider(FeignClientProperties.class);
+		verify(beanProvider).getIfAvailable();
+	}
+
+	@Test
+	void shouldMatchWhenFeignClientPropertiesBeanIsMissing() {
+		when(beanProvider.getIfAvailable()).thenReturn(null);
+
+		assertThat(condition.matches(context, metadata)).isTrue();
+		verify(environment, never()).getProperty("feign.client.name");
+	}
+
+	@Test
+	void shouldMatchWhenConfigMapIsMissing() {
+		FeignClientProperties feignClientProperties = mock(FeignClientProperties.class);
+		when(beanProvider.getIfAvailable()).thenReturn(feignClientProperties);
+		when(feignClientProperties.getConfig()).thenReturn(null);
+
+		assertThat(condition.matches(context, metadata)).isTrue();
+		verify(environment, never()).getProperty("feign.client.name");
+	}
+
+	@Test
+	void shouldMatchWhenConfigMapDoesNotContainTheConfig() {
+		FeignClientProperties feignClientProperties = mock(FeignClientProperties.class);
+		when(beanProvider.getIfAvailable()).thenReturn(feignClientProperties);
+		when(context.getEnvironment()).thenReturn(environment);
+		when(environment.getProperty("feign.client.name")).thenReturn("foo");
+		when(feignClientProperties.getConfig()).thenReturn(new HashMap<>());
+
+		assertThat(condition.matches(context, metadata)).isTrue();
+		verify(environment).getProperty("feign.client.name");
+	}
+
+	@Test
+	void shouldMatchWhenClientNameIsNull() {
+		FeignClientProperties feignClientProperties = mock(FeignClientProperties.class);
+		when(beanProvider.getIfAvailable()).thenReturn(feignClientProperties);
+		when(context.getEnvironment()).thenReturn(environment);
+		when(environment.getProperty("feign.client.name")).thenReturn(null);
+		when(feignClientProperties.getConfig()).thenReturn(new HashMap<>());
+
+		assertThat(condition.matches(context, metadata)).isTrue();
+		verify(environment).getProperty("feign.client.name");
+	}
+
+	@Test
+	void shouldMatchWhenClientNameIsEmpty() {
+		FeignClientProperties feignClientProperties = mock(FeignClientProperties.class);
+		when(beanProvider.getIfAvailable()).thenReturn(feignClientProperties);
+		when(context.getEnvironment()).thenReturn(environment);
+		when(environment.getProperty("feign.client.name")).thenReturn("");
+		when(feignClientProperties.getConfig()).thenReturn(new HashMap<>());
+
+		assertThat(condition.matches(context, metadata)).isTrue();
+
+		verify(environment).getProperty("feign.client.name");
+	}
+
+	@Test
+	void shouldMatchWhenConfigMapContainsNullConfig() {
+		FeignClientProperties feignClientProperties = mock(FeignClientProperties.class);
+		when(beanProvider.getIfAvailable()).thenReturn(feignClientProperties);
+		when(context.getEnvironment()).thenReturn(environment);
+		when(environment.getProperty("feign.client.name")).thenReturn("foo");
+		when(feignClientProperties.getConfig()).thenReturn(Maps.newHashMap("foo", null));
+
+		assertThat(condition.matches(context, metadata)).isTrue();
+		verify(environment).getProperty("feign.client.name");
+	}
+
+	@Test
+	void shouldMatchWhenMetricsConfigurationIsMissing() {
+		FeignClientProperties feignClientProperties = mock(FeignClientProperties.class);
+		FeignClientProperties.FeignClientConfiguration feignClientConfig = mock(
+				FeignClientProperties.FeignClientConfiguration.class);
+		when(beanProvider.getIfAvailable()).thenReturn(feignClientProperties);
+		when(context.getEnvironment()).thenReturn(environment);
+		when(environment.getProperty("feign.client.name")).thenReturn("foo");
+		when(feignClientProperties.getConfig()).thenReturn(Maps.newHashMap("foo", feignClientConfig));
+		when(feignClientConfig.getMetrics()).thenReturn(null);
+
+		assertThat(condition.matches(context, metadata)).isTrue();
+		verify(environment).getProperty("feign.client.name");
+	}
+
+	@Test
+	void shouldMatchWhenEnabledFlagIsNotSet() {
+		FeignClientProperties feignClientProperties = mock(FeignClientProperties.class);
+		FeignClientProperties.FeignClientConfiguration feignClientConfig = mock(
+				FeignClientProperties.FeignClientConfiguration.class);
+		when(beanProvider.getIfAvailable()).thenReturn(feignClientProperties);
+		when(context.getEnvironment()).thenReturn(environment);
+		when(environment.getProperty("feign.client.name")).thenReturn("foo");
+		when(feignClientProperties.getConfig()).thenReturn(Maps.newHashMap("foo", feignClientConfig));
+		when(feignClientConfig.getMetrics()).thenReturn(new FeignClientProperties.MetricsProperties());
+
+		assertThat(condition.matches(context, metadata)).isTrue();
+		verify(environment).getProperty("feign.client.name");
+	}
+
+	@Test
+	void shouldMatchWhenEnabledFlagIsNull() {
+		FeignClientProperties feignClientProperties = mock(FeignClientProperties.class);
+		FeignClientProperties.FeignClientConfiguration feignClientConfig = mock(
+				FeignClientProperties.FeignClientConfiguration.class);
+		when(beanProvider.getIfAvailable()).thenReturn(feignClientProperties);
+		when(context.getEnvironment()).thenReturn(environment);
+		when(environment.getProperty("feign.client.name")).thenReturn("foo");
+		when(feignClientProperties.getConfig()).thenReturn(Maps.newHashMap("foo", feignClientConfig));
+		FeignClientProperties.MetricsProperties metricsProperties = new FeignClientProperties.MetricsProperties();
+		metricsProperties.setEnabled(null);
+		when(feignClientConfig.getMetrics()).thenReturn(metricsProperties);
+
+		assertThat(condition.matches(context, metadata)).isTrue();
+		verify(environment).getProperty("feign.client.name");
+	}
+
+	@Test
+	void shouldMatchWhenMetricsConfigurationIsEnabled() {
+		FeignClientProperties feignClientProperties = mock(FeignClientProperties.class);
+		FeignClientProperties.FeignClientConfiguration feignClientConfig = mock(
+				FeignClientProperties.FeignClientConfiguration.class);
+		when(beanProvider.getIfAvailable()).thenReturn(feignClientProperties);
+		when(context.getEnvironment()).thenReturn(environment);
+		when(environment.getProperty("feign.client.name")).thenReturn("foo");
+		when(feignClientProperties.getConfig()).thenReturn(Maps.newHashMap("foo", feignClientConfig));
+		FeignClientProperties.MetricsProperties metricsProperties = new FeignClientProperties.MetricsProperties();
+		metricsProperties.setEnabled(true);
+		when(feignClientConfig.getMetrics()).thenReturn(metricsProperties);
+
+		assertThat(condition.matches(context, metadata)).isTrue();
+		verify(environment).getProperty("feign.client.name");
+	}
+
+	@Test
+	void shouldNotMatchWhenMetricsConfigurationIsEnabled() {
+		FeignClientProperties feignClientProperties = mock(FeignClientProperties.class);
+		FeignClientProperties.FeignClientConfiguration feignClientConfig = mock(
+				FeignClientProperties.FeignClientConfiguration.class);
+		when(beanProvider.getIfAvailable()).thenReturn(feignClientProperties);
+		when(context.getEnvironment()).thenReturn(environment);
+		when(environment.getProperty("feign.client.name")).thenReturn("foo");
+		when(feignClientProperties.getConfig()).thenReturn(Maps.newHashMap("foo", feignClientConfig));
+		FeignClientProperties.MetricsProperties metricsProperties = new FeignClientProperties.MetricsProperties();
+		metricsProperties.setEnabled(false);
+		when(feignClientConfig.getMetrics()).thenReturn(metricsProperties);
+
+		assertThat(condition.matches(context, metadata)).isFalse();
+		verify(environment).getProperty("feign.client.name");
+	}
+
+}

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientOverrideDefaultsTests.java

@@ -16,6 +16,9 @@
 
 package org.springframework.cloud.openfeign;
 
+import java.util.Map;
+
+import feign.Capability;
 import feign.Contract;
 import feign.ExceptionPropagationPolicy;
 import feign.Logger;
@@ -28,6 +31,7 @@ import feign.auth.BasicAuthRequestInterceptor;
 import feign.codec.Decoder;
 import feign.codec.Encoder;
 import feign.codec.ErrorDecoder;
+import feign.micrometer.MicrometerCapability;
 import feign.optionals.OptionalDecoder;
 import feign.querymap.BeanQueryMapEncoder;
 import feign.slf4j.Slf4jLogger;
@@ -48,6 +52,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author Spencer Gibb
+ * @author Jonatan Ivanov
  */
 @SpringBootTest(classes = FeignClientOverrideDefaultsTests.TestConfiguration.class)
 @DirtiesContext
@@ -137,6 +142,22 @@ class FeignClientOverrideDefaultsTests {
 				.containsValues(ExceptionPropagationPolicy.UNWRAP);
 	}
 
+	@Test
+	void shouldOverrideMicrometerCapability() {
+		assertThat(context.getInstance("foo", MicrometerCapability.class))
+				.isExactlyInstanceOf(TestMicrometerCapability.class);
+		Map<String, Capability> fooCapabilities = context.getInstances("foo", Capability.class);
+		assertThat(fooCapabilities).hasSize(1);
+		assertThat(fooCapabilities.get("micrometerCapability")).isExactlyInstanceOf(TestMicrometerCapability.class);
+
+		assertThat(context.getInstance("bar", MicrometerCapability.class))
+				.isExactlyInstanceOf(TestMicrometerCapability.class);
+		Map<String, Capability> barCapabilities = context.getInstances("bar", Capability.class);
+		assertThat(barCapabilities).hasSize(2);
+		assertThat(barCapabilities.get("micrometerCapability")).isExactlyInstanceOf(TestMicrometerCapability.class);
+		assertThat(barCapabilities.get("noOpCapability")).isExactlyInstanceOf(NoOpCapability.class);
+	}
+
 	@FeignClient(name = "foo", url = "https://foo", configuration = FooConfiguration.class)
 	interface FooClient {
 
@@ -164,6 +185,11 @@ class FeignClientOverrideDefaultsTests {
 			};
 		}
 
+		@Bean
+		MicrometerCapability micrometerCapability() {
+			return new TestMicrometerCapability();
+		}
+
 	}
 
 	public static class FooConfiguration {
@@ -232,6 +258,19 @@ class FeignClientOverrideDefaultsTests {
 			return ExceptionPropagationPolicy.UNWRAP;
 		}
 
+		@Bean
+		public Capability noOpCapability() {
+			return new NoOpCapability();
+		}
+
+	}
+
+	private static class TestMicrometerCapability extends feign.micrometer.MicrometerCapability {
+
+	}
+
+	private static class NoOpCapability implements Capability {
+
 	}
 
 }

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientPropertiesTests.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2021-2021 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.openfeign;
+
+import java.util.Map;
+
+import org.assertj.core.util.Maps;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsAndHashCodeConsistency;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsConsistency;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsReflexivity;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsSymmetricity;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsTransitivity;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertHashCodeConsistency;
+
+/**
+ * @author Jonatan Ivanov
+ */
+class FeignClientPropertiesTests {
+
+	@Test
+	void shouldDefaultToValuesWhenFieldsNotSet() {
+		FeignClientProperties properties = new FeignClientProperties();
+		assertThat(properties.isDefaultToProperties()).isTrue();
+		assertThat(properties.getDefaultConfig()).isEqualTo("default");
+		assertThat(properties.getConfig()).isEmpty();
+		assertThat(properties.isDecodeSlash()).isTrue();
+	}
+
+	@Test
+	void shouldReturnValuesWhenSet() {
+		FeignClientProperties properties = new FeignClientProperties();
+		properties.setDefaultToProperties(false);
+		properties.setDefaultConfig("custom");
+		Map<String, FeignClientProperties.FeignClientConfiguration> configMap = Maps.newHashMap("foo", null);
+		properties.setConfig(configMap);
+		properties.setDecodeSlash(false);
+
+		assertThat(properties.isDefaultToProperties()).isFalse();
+		assertThat(properties.getDefaultConfig()).isEqualTo("custom");
+		assertThat(properties.getConfig()).isSameAs(configMap);
+		assertThat(properties.isDecodeSlash()).isFalse();
+	}
+
+	/**
+	 * Sanity-checks equals and hashCode contracts but does not check every variation of
+	 * the fields.
+	 */
+	@Test
+	void shouldHaveSomewhatValidEqualsAndHashCode() {
+		FeignClientProperties propsOne = new FeignClientProperties();
+		FeignClientProperties propsTwo = new FeignClientProperties();
+		FeignClientProperties propsThree = new FeignClientProperties();
+		FeignClientProperties differentProps = new FeignClientProperties();
+		differentProps.setDecodeSlash(false);
+
+		assertEqualsReflexivity(propsOne);
+
+		assertEqualsSymmetricity(propsOne, propsTwo);
+		assertEqualsSymmetricity(propsOne, differentProps);
+		assertEqualsSymmetricity(propsOne, 42);
+
+		assertEqualsTransitivity(propsOne, propsTwo, propsThree);
+
+		assertEqualsConsistency(propsOne, propsTwo);
+		assertEqualsConsistency(propsOne, differentProps);
+		assertEqualsConsistency(propsOne, 42);
+		assertEqualsConsistency(propsOne, null);
+
+		assertHashCodeConsistency(propsOne);
+		assertEqualsAndHashCodeConsistency(propsOne, propsTwo);
+	}
+
+}

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientUsingConfigurerTest.java

@@ -19,9 +19,11 @@ package org.springframework.cloud.openfeign;
 import java.lang.reflect.Field;
 import java.util.List;
 
+import feign.Capability;
 import feign.Feign;
 import feign.Logger;
 import feign.RequestInterceptor;
+import feign.micrometer.MicrometerCapability;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -40,6 +42,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author matt king
+ * @author Jonatan Ivanov
  */
 @DirtiesContext
 @RunWith(SpringJUnit4ClassRunner.class)
@@ -67,6 +70,10 @@ public class FeignClientUsingConfigurerTest {
 		List<RequestInterceptor> interceptors = (List) getBuilderValue(builder, "requestInterceptors");
 		assertThat(interceptors.size()).as("interceptors not set").isEqualTo(3);
 		assertThat(getBuilderValue(builder, "logLevel")).as("log level not set").isEqualTo(Logger.Level.FULL);
+
+		List<Capability> capabilities = (List) getBuilderValue(builder, "capabilities");
+		assertThat(capabilities).hasSize(2).hasAtLeastOneElementOfType(NoOpCapability.class)
+				.hasAtLeastOneElementOfType(MicrometerCapability.class);
 	}
 
 	private Object getBuilderValue(Feign.Builder builder, String member) {
@@ -84,9 +91,12 @@ public class FeignClientUsingConfigurerTest {
 		Feign.Builder builder = factoryBean.feign(context);
 
 		List<RequestInterceptor> interceptors = (List) getBuilderValue(builder, "requestInterceptors");
-
 		assertThat(interceptors).as("interceptors not set").isEmpty();
 		assertThat(factoryBean.isInheritParentContext()).as("is inheriting from parent configuration").isFalse();
+
+		List<Capability> capabilities = (List) getBuilderValue(builder, "capabilities");
+		assertThat(capabilities).hasSize(2).hasAtLeastOneElementOfType(NoOpCapability.class)
+				.hasAtLeastOneElementOfType(MicrometerCapability.class);
 	}
 
 	@Test
@@ -97,6 +107,10 @@ public class FeignClientUsingConfigurerTest {
 		Feign.Builder builder = factoryBean.feign(context);
 
 		assertThat(getBuilderValue(builder, "logLevel")).as("log level not set").isEqualTo(Logger.Level.HEADERS);
+
+		List<Capability> capabilities = (List) getBuilderValue(builder, "capabilities");
+		assertThat(capabilities).hasSize(2).hasAtLeastOneElementOfType(NoOpCapability.class)
+				.hasAtLeastOneElementOfType(MicrometerCapability.class);
 	}
 
 	@EnableAutoConfiguration
@@ -110,6 +124,11 @@ public class FeignClientUsingConfigurerTest {
 			};
 		}
 
+		@Bean
+		public NoOpCapability noOpCapability() {
+			return new NoOpCapability();
+		}
+
 	}
 
 	public static class NoInheritConfiguration {
@@ -119,6 +138,11 @@ public class FeignClientUsingConfigurerTest {
 			return Logger.Level.HEADERS;
 		}
 
+		@Bean
+		public NoOpCapability noOpCapability() {
+			return new NoOpCapability();
+		}
+
 		@Bean
 		public FeignClientConfigurer feignClientConfigurer() {
 			return new FeignClientConfigurer() {
@@ -143,4 +167,8 @@ public class FeignClientUsingConfigurerTest {
 
 	}
 
+	private static class NoOpCapability implements Capability {
+
+	}
+
 }

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientUsingPropertiesTests.java

@@ -34,6 +34,8 @@ import java.util.stream.Stream;
 
 import javax.servlet.http.HttpServletRequest;
 
+import feign.Capability;
+import feign.Feign;
 import feign.InvocationHandlerFactory;
 import feign.Request;
 import feign.RequestInterceptor;
@@ -43,6 +45,7 @@ import feign.Retryer;
 import feign.codec.EncodeException;
 import feign.codec.Encoder;
 import feign.codec.ErrorDecoder;
+import feign.micrometer.MicrometerCapability;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -76,6 +79,7 @@ import static org.springframework.boot.test.context.SpringBootTest.WebEnvironmen
  * @author Eko Kurniawan Khannedy
  * @author Olga Maciaszek-Sharma
  * @author Ilia Ilinykh
+ * @author Jonatan Ivanov
  */
 @SuppressWarnings("FieldMayBeFinal")
 @RunWith(SpringJUnit4ClassRunner.class)
@@ -232,8 +236,22 @@ public class FeignClientUsingPropertiesTests {
 		assertThat(options.readTimeoutMillis()).isEqualTo(5000);
 	}
 
+	@Test
+	public void clientShouldContainCapabilities() {
+		fooFactoryBean.setApplicationContext(applicationContext);
+		Feign.Builder feignBuilder = fooFactoryBean.feign(context);
+		FooClient fooClient = feignBuilder.target(FooClient.class, "http://localhost:" + port);
+
+		String response = fooClient.foo();
+		assertThat(response).isEqualTo("OK");
+		List<Capability> capabilities = (List) ReflectionTestUtils.getField(feignBuilder, "capabilities");
+		assertThat(capabilities).hasSize(2).hasAtLeastOneElementOfType(NoOpCapability.class)
+				.hasAtLeastOneElementOfType(MicrometerCapability.class);
+	}
+
 	private Request.Options getRequestOptions(Proxy client) {
-		Object invocationHandler = ReflectionTestUtils.getField(client, "h");
+		Object invocationHandlerLambda = ReflectionTestUtils.getField(client, "h");
+		Object invocationHandler = ReflectionTestUtils.getField(invocationHandlerLambda, "arg$2");
 		Map<Method, InvocationHandlerFactory.MethodHandler> dispatch = (Map<Method, InvocationHandlerFactory.MethodHandler>) ReflectionTestUtils
 				.getField(Objects.requireNonNull(invocationHandler), "dispatch");
 		Method key = new ArrayList<>(dispatch.keySet()).get(0);
@@ -385,4 +403,8 @@ public class FeignClientUsingPropertiesTests {
 
 	}
 
+	public static class NoOpCapability implements Capability {
+
+	}
+
 }

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/MetricsPropertiesTests.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2021-2021 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.openfeign;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsAndHashCodeConsistency;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsConsistency;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsReflexivity;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsSymmetricity;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertEqualsTransitivity;
+import static org.springframework.cloud.openfeign.test.EqualsAndHashCodeAssert.assertHashCodeConsistency;
+
+/**
+ * @author Jonatan Ivanov
+ */
+class MetricsPropertiesTests {
+
+	@Test
+	void shouldBeEnabledByDefault() {
+		FeignClientProperties.MetricsProperties properties = new FeignClientProperties.MetricsProperties();
+		assertThat(properties.getEnabled()).isTrue();
+	}
+
+	@Test
+	void shouldBeDisabledWhenSet() {
+		FeignClientProperties.MetricsProperties properties = new FeignClientProperties.MetricsProperties();
+		properties.setEnabled(false);
+		assertThat(properties.getEnabled()).isFalse();
+	}
+
+	/**
+	 * Sanity-checks equals and hashCode contracts but does not check every variation of
+	 * the fields.
+	 */
+	@Test
+	void shouldHaveSomewhatValidEqualsAndHashCode() {
+		FeignClientProperties.MetricsProperties propertyOne = new FeignClientProperties.MetricsProperties();
+		FeignClientProperties.MetricsProperties propertyTwo = new FeignClientProperties.MetricsProperties();
+		FeignClientProperties.MetricsProperties propertyThree = new FeignClientProperties.MetricsProperties();
+		FeignClientProperties.MetricsProperties differentProperty = new FeignClientProperties.MetricsProperties();
+		differentProperty.setEnabled(false);
+
+		assertEqualsReflexivity(propertyOne);
+
+		assertEqualsSymmetricity(propertyOne, propertyTwo);
+		assertEqualsSymmetricity(propertyOne, differentProperty);
+		assertEqualsSymmetricity(propertyOne, 42);
+
+		assertEqualsTransitivity(propertyOne, propertyTwo, propertyThree);
+
+		assertEqualsConsistency(propertyOne, propertyTwo);
+		assertEqualsConsistency(propertyOne, differentProperty);
+		assertEqualsConsistency(propertyOne, 42);
+		assertEqualsConsistency(propertyOne, null);
+
+		assertHashCodeConsistency(propertyOne);
+		assertEqualsAndHashCodeConsistency(propertyOne, propertyTwo);
+	}
+
+}

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/test/EqualsAndHashCodeAssert.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2021-2021 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.openfeign.test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * A few assertions to sanity-check equals and hashCode contracts:
+ * https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html See
+ * {@link Object#equals(Object)} and {@link Object#hashCode()}.
+ *
+ * @author Jonatan Ivanov
+ */
+public class EqualsAndHashCodeAssert {
+
+	/**
+	 * Checks if equals is reflexive: for any non-null reference value x, x.equals(x)
+	 * should return true.
+	 * @param object the reference object to check
+	 */
+	public static void assertEqualsReflexivity(Object object) {
+		assertThat(object.equals(object)).isTrue();
+	}
+
+	/**
+	 * Checks if equals is symmetric: for any non-null reference values x and y,
+	 * x.equals(y) should return true if and only if y.equals(x) returns true The user of
+	 * this method should call this at least twice: once with objects that are equal and
+	 * once with objects that are not.
+	 * @param objectOne a reference object to check
+	 * @param objectTwo another reference object to check
+	 */
+	public static void assertEqualsSymmetricity(Object objectOne, Object objectTwo) {
+		assertThat(objectOne.equals(objectTwo)).isEqualTo(objectTwo.equals(objectOne));
+	}
+
+	/**
+	 * Checks if equals is transitive: for any non-null reference values x, y, and z, if
+	 * x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should
+	 * return true.
+	 * @param objectOne a reference object to check
+	 * @param objectTwo another reference object to check
+	 * @param objectThree and the third reference object to check
+	 */
+	public static void assertEqualsTransitivity(Object objectOne, Object objectTwo, Object objectThree) {
+		assertThat(objectOne.equals(objectTwo)).isTrue();
+		assertThat(objectTwo.equals(objectThree)).isTrue();
+		assertThat(objectOne.equals(objectThree)).isTrue();
+	}
+
+	/**
+	 * Tries to check if equals is consistent: for any non-null reference values x and y,
+	 * multiple invocations of x.equals(y) consistently return true or consistently return
+	 * false. The user of this method should call this at least twice: once with objects
+	 * that are equal and once with objects that are not.
+	 * @param objectOne a reference object to check
+	 * @param objectTwo another reference object to check
+	 */
+	public static void assertEqualsConsistency(Object objectOne, Object objectTwo) {
+		boolean equality = objectOne.equals(objectTwo);
+		for (int i = 0; i < 100; i++) {
+			assertThat(objectOne.equals(objectTwo)).isEqualTo(equality);
+		}
+	}
+
+	/**
+	 * Tries to check if hashCode is consistent: whenever it is invoked on the same object
+	 * more than once during an execution of a Java application, the hashCode method must
+	 * consistently return the same integer.
+	 * @param object the reference object to check
+	 */
+	public static void assertHashCodeConsistency(Object object) {
+		int hashCode = object.hashCode();
+		for (int i = 0; i < 100; i++) {
+			assertThat(object.hashCode()).isEqualTo(hashCode);
+		}
+	}
+
+	/**
+	 * Checks if equals and hashCode are consistent to each other: if two objects are
+	 * equal according to the equals method, then calling the hashCode method on each of
+	 * the two objects must produce the same integer result.
+	 * @param objectOne a reference object to check
+	 * @param objectTwo another reference object to check
+	 */
+	public static void assertEqualsAndHashCodeConsistency(Object objectOne, Object objectTwo) {
+		assertThat(objectOne.equals(objectTwo)).isTrue();
+		assertThat(objectOne.hashCode()).isEqualTo(objectTwo.hashCode());
+	}
+
+}

spring-cloud-openfeign-core/src/test/resources/application.yml

@@ -34,3 +34,11 @@ feignClient:
   methodLevelRequestMappingPath: /hello2
   myPlaceholderHeader: myPlaceholderHeaderValue
 management.endpoints.web.expose: '*'
+
+---
+spring.config.activate.on-profile: no-metrics
+feign.metrics.enabled: false
+
+---
+spring.config.activate.on-profile: no-foo-metrics
+feign.client.config.foo.metrics.enabled: false

spring-cloud-openfeign-core/src/test/resources/feign-properties.properties

@@ -8,6 +8,7 @@ feign.client.config.default.loggerLevel=full
 feign.client.config.default.errorDecoder=org.springframework.cloud.openfeign.FeignClientUsingPropertiesTests.DefaultErrorDecoder
 feign.client.config.default.retryer=org.springframework.cloud.openfeign.FeignClientUsingPropertiesTests.NoRetryer
 feign.client.config.default.decode404=true
+feign.client.config.default.capabilities=org.springframework.cloud.openfeign.FeignClientUsingPropertiesTests.NoOpCapability
 feign.client.config.foo.requestInterceptors[0]=org.springframework.cloud.openfeign.FeignClientUsingPropertiesTests.FooRequestInterceptor
 feign.client.config.foo.requestInterceptors[1]=org.springframework.cloud.openfeign.FeignClientUsingPropertiesTests.BarRequestInterceptor
 feign.client.config.singleValue.defaultRequestHeaders[singleValueHeaders]=header