Use uriTemplate attribute in metrics

docs/modules/ROOT/pages/spring-cloud-commons/loadbalancer.adoc

@@ -506,6 +506,12 @@ set the value of the `spring.cloud.loadbalancer.stats.micrometer.enabled` to `tr
 
 Additional information regarding the service instances, request data, and response data is added to metrics via tags whenever available.
 
+NOTE: For `WebClient` and `RestClient`-backed load-balancing, we use `uriTemplate` for the `uri` tag whenever available.
+
+TIP: It is possible to disable adding `path` to `uri` tag by setting `spring.cloud.loadbalancer.stats.include-path` to `false`.
+
+WARNING: As with `RestTemplate`-backed load-balancing, we don't have access to `uriTemplate`, full path is always used in the `uri` tag. In order to avoid high cardinality issues, if path is a high cardinality value (for example, `/orders/\{id\}`, where `id` takes a big number of values), it is strongly recommended to disable adding path to `uri` tag by setting `spring.cloud.loadbalancer.stats.include-path` to `false`.
+
 NOTE: For some implementations, such as `BlockingLoadBalancerClient`, request and response data might not be available, as we establish generic types from arguments and might not be able to determine the types and read the data.
 
 NOTE: The meters are registered in the registry when at least one record is added for a given meter.

docs/modules/ROOT/partials/_configprops.adoc

@@ -66,6 +66,7 @@
 |spring.cloud.loadbalancer.retry.retryable-exceptions | `+++{}+++` | A `Set` of `Throwable` classes that should trigger a retry.
 |spring.cloud.loadbalancer.retry.retryable-status-codes | `+++{}+++` | A `Set` of status codes that should trigger a retry.
 |spring.cloud.loadbalancer.service-discovery.timeout |  | String representation of Duration of the timeout for calls to service discovery.
+|spring.cloud.loadbalancer.stats.include-path | `+++true+++` | Indicates whether the {@code path} should be added to {@code uri} tag in metrics. When {@link RestTemplate} is used to execute load-balanced requests with high cardinality paths, setting it to {@code false} is recommended.
 |spring.cloud.loadbalancer.stats.micrometer.enabled | `+++false+++` | Enables Spring Cloud LoadBalancer Micrometer stats.
 |spring.cloud.loadbalancer.sticky-session.add-service-instance-cookie | `+++false+++` | Indicates whether a cookie with the newly selected instance should be added by LoadBalancer.
 |spring.cloud.loadbalancer.sticky-session.instance-id-cookie-name | `+++sc-lb-instance-id+++` | The name of the cookie holding the preferred instance id.

spring-cloud-commons/src/main/java/org/springframework/cloud/client/loadbalancer/LoadBalancerProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -33,6 +33,7 @@
 import org.springframework.core.env.PropertyResolver;
 import org.springframework.http.HttpMethod;
 import org.springframework.util.LinkedCaseInsensitiveMap;
+import org.springframework.web.client.RestTemplate;
 
 /**
  * The base configuration bean for Spring Cloud LoadBalancer.
@@ -90,10 +91,20 @@ public class LoadBalancerProperties {
 
 	/**
 	 * Properties for
-	 * {@link org.springframework.cloud.loadbalancer.core.SubsetServiceInstanceListSupplier}.
+	 * {@code org.springframework.cloud.loadbalancer.core.SubsetServiceInstanceListSupplier}.
 	 */
 	private Subset subset = new Subset();
 
+	/**
+	 * Enabling X-Forwarded Host and Proto Headers.
+	 */
+	private XForwarded xForwarded = new XForwarded();
+
+	/**
+	 * Properties for LoadBalancer metrics.
+	 */
+	private Stats stats = new Stats();
+
 	public HealthCheck getHealthCheck() {
 		return healthCheck;
 	}
@@ -134,11 +145,6 @@ public void setHintHeaderName(String hintHeaderName) {
 		this.hintHeaderName = hintHeaderName;
 	}
 
-	/**
-	 * Enabling X-Forwarded Host and Proto Headers.
-	 */
-	private XForwarded xForwarded = new XForwarded();
-
 	// TODO: fix spelling in a major release
 	public void setxForwarded(XForwarded xForwarded) {
 		this.xForwarded = xForwarded;
@@ -164,6 +170,14 @@ public void setCallGetWithRequestOnDelegates(boolean callGetWithRequestOnDelegat
 		this.callGetWithRequestOnDelegates = callGetWithRequestOnDelegates;
 	}
 
+	public Stats getStats() {
+		return stats;
+	}
+
+	public void setStats(Stats stats) {
+		this.stats = stats;
+	}
+
 	public static class StickySession {
 
 		/**
@@ -539,4 +553,23 @@ public void setSize(int size) {
 
 	}
 
+	public static class Stats {
+
+		/**
+		 * Indicates whether the {@code path} should be added to {@code uri} tag in
+		 * metrics. When {@link RestTemplate} is used to execute load-balanced requests
+		 * with high cardinality paths, setting it to {@code false} is recommended.
+		 */
+		private boolean includePath = true;
+
+		public boolean isIncludePath() {
+			return includePath;
+		}
+
+		public void setIncludePath(boolean includePath) {
+			this.includePath = includePath;
+		}
+
+	}
+
 }

spring-cloud-loadbalancer/src/main/java/org/springframework/cloud/loadbalancer/config/LoadBalancerStatsAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -21,6 +21,8 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.cloud.client.ServiceInstance;
+import org.springframework.cloud.client.loadbalancer.reactive.ReactiveLoadBalancer;
 import org.springframework.cloud.loadbalancer.stats.MicrometerStatsLoadBalancerLifecycle;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -38,8 +40,9 @@ public class LoadBalancerStatsAutoConfiguration {
 
 	@Bean
 	@ConditionalOnBean(MeterRegistry.class)
-	public MicrometerStatsLoadBalancerLifecycle micrometerStatsLifecycle(MeterRegistry meterRegistry) {
-		return new MicrometerStatsLoadBalancerLifecycle(meterRegistry);
+	public MicrometerStatsLoadBalancerLifecycle micrometerStatsLifecycle(MeterRegistry meterRegistry,
+			ReactiveLoadBalancer.Factory<ServiceInstance> loadBalancerFactory) {
+		return new MicrometerStatsLoadBalancerLifecycle(meterRegistry, loadBalancerFactory);
 	}
 
 }

spring-cloud-loadbalancer/src/main/java/org/springframework/cloud/loadbalancer/stats/LoadBalancerTags.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -16,11 +16,17 @@
 
 package org.springframework.cloud.loadbalancer.stats;
 
+import java.util.Collections;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+
 import io.micrometer.core.instrument.Tag;
 import io.micrometer.core.instrument.Tags;
 
 import org.springframework.cloud.client.ServiceInstance;
 import org.springframework.cloud.client.loadbalancer.CompletionContext;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerProperties;
 import org.springframework.cloud.client.loadbalancer.RequestData;
 import org.springframework.cloud.client.loadbalancer.RequestDataContext;
 import org.springframework.cloud.client.loadbalancer.ResponseData;
@@ -30,17 +36,25 @@
  * Utility class for building metrics tags for load-balanced calls.
  *
  * @author Olga Maciaszek-Sharma
+ * @author Jaroslaw Dembek
  * @since 3.0.0
  */
-final class LoadBalancerTags {
+class LoadBalancerTags {
 
 	static final String UNKNOWN = "UNKNOWN";
 
-	private LoadBalancerTags() {
-		throw new UnsupportedOperationException("Cannot instantiate utility class");
+	private final LoadBalancerProperties properties;
+
+	// Not using class references in case not in classpath
+	private static final Set<String> URI_TEMPLATE_ATTRIBUTES = Set.of(
+			"org.springframework.web.reactive.function.client.WebClient.uriTemplate",
+			"org.springframework.web.client.RestClient.uriTemplate");
+
+	LoadBalancerTags(LoadBalancerProperties properties) {
+		this.properties = properties;
 	}
 
-	static Iterable<Tag> buildSuccessRequestTags(CompletionContext<Object, ServiceInstance, Object> completionContext) {
+	Iterable<Tag> buildSuccessRequestTags(CompletionContext<Object, ServiceInstance, Object> completionContext) {
 		ServiceInstance serviceInstance = completionContext.getLoadBalancerResponse().getServer();
 		Tags tags = Tags.of(buildServiceInstanceTags(serviceInstance));
 		Object clientResponse = completionContext.getClientResponse();
@@ -69,12 +83,23 @@ private static int statusValue(ResponseData responseData) {
 		return responseData.getHttpStatus() != null ? responseData.getHttpStatus().value() : 200;
 	}
 
-	private static String getPath(RequestData requestData) {
-		return requestData.getUrl() != null ? requestData.getUrl().getPath() : UNKNOWN;
+	private String getPath(RequestData requestData) {
+		if (!properties.getStats().isIncludePath()) {
+			return UNKNOWN;
+		}
+		Optional<Object> uriTemplateValue = Optional.ofNullable(requestData.getAttributes())
+			.orElse(Collections.emptyMap())
+			.keySet()
+			.stream()
+			.filter(URI_TEMPLATE_ATTRIBUTES::contains)
+			.map(key -> requestData.getAttributes().get(key))
+			.filter(Objects::nonNull)
+			.findAny();
+		return uriTemplateValue.map(uriTemplate -> (String) uriTemplate)
+			.orElseGet(() -> (requestData.getUrl() != null) ? requestData.getUrl().getPath() : UNKNOWN);
 	}
 
-	static Iterable<Tag> buildDiscardedRequestTags(
-			CompletionContext<Object, ServiceInstance, Object> completionContext) {
+	Iterable<Tag> buildDiscardedRequestTags(CompletionContext<Object, ServiceInstance, Object> completionContext) {
 		if (completionContext.getLoadBalancerRequest().getContext() instanceof RequestDataContext) {
 			RequestData requestData = ((RequestDataContext) completionContext.getLoadBalancerRequest().getContext())
 				.getClientRequest();
@@ -92,7 +117,7 @@ private static String getHost(RequestData requestData) {
 		return requestData.getUrl() != null ? requestData.getUrl().getHost() : UNKNOWN;
 	}
 
-	static Iterable<Tag> buildFailedRequestTags(CompletionContext<Object, ServiceInstance, Object> completionContext) {
+	Iterable<Tag> buildFailedRequestTags(CompletionContext<Object, ServiceInstance, Object> completionContext) {
 		ServiceInstance serviceInstance = completionContext.getLoadBalancerResponse().getServer();
 		Tags tags = Tags.of(buildServiceInstanceTags(serviceInstance)).and(exception(completionContext.getThrowable()));
 		if (completionContext.getLoadBalancerRequest().getContext() instanceof RequestDataContext) {

spring-cloud-loadbalancer/src/main/java/org/springframework/cloud/loadbalancer/stats/MicrometerStatsLoadBalancerLifecycle.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -27,31 +27,50 @@
 
 import org.springframework.cloud.client.ServiceInstance;
 import org.springframework.cloud.client.loadbalancer.CompletionContext;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerClientsProperties;
 import org.springframework.cloud.client.loadbalancer.LoadBalancerLifecycle;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerProperties;
 import org.springframework.cloud.client.loadbalancer.Request;
 import org.springframework.cloud.client.loadbalancer.Response;
 import org.springframework.cloud.client.loadbalancer.TimedRequestContext;
+import org.springframework.cloud.client.loadbalancer.reactive.ReactiveLoadBalancer;
+import org.springframework.cloud.loadbalancer.support.LoadBalancerClientFactory;
 
-import static org.springframework.cloud.loadbalancer.stats.LoadBalancerTags.buildDiscardedRequestTags;
-import static org.springframework.cloud.loadbalancer.stats.LoadBalancerTags.buildFailedRequestTags;
 import static org.springframework.cloud.loadbalancer.stats.LoadBalancerTags.buildServiceInstanceTags;
-import static org.springframework.cloud.loadbalancer.stats.LoadBalancerTags.buildSuccessRequestTags;
 
 /**
  * An implementation of {@link LoadBalancerLifecycle} that records metrics for
  * load-balanced calls.
  *
  * @author Olga Maciaszek-Sharma
+ * @author Jaroslaw Dembek
  * @since 3.0.0
  */
 public class MicrometerStatsLoadBalancerLifecycle implements LoadBalancerLifecycle<Object, Object, ServiceInstance> {
 
 	private final MeterRegistry meterRegistry;
 
+	private final ReactiveLoadBalancer.Factory<ServiceInstance> loadBalancerFactory;
+
 	private final ConcurrentHashMap<ServiceInstance, AtomicLong> activeRequestsPerInstance = new ConcurrentHashMap<>();
 
-	public MicrometerStatsLoadBalancerLifecycle(MeterRegistry meterRegistry) {
+	public MicrometerStatsLoadBalancerLifecycle(MeterRegistry meterRegistry,
+			ReactiveLoadBalancer.Factory<ServiceInstance> loadBalancerFactory) {
 		this.meterRegistry = meterRegistry;
+		this.loadBalancerFactory = loadBalancerFactory;
+	}
+
+	/**
+	 * Creates a MicrometerStatsLoadBalancerLifecycle instance based on the provided
+	 * {@link MeterRegistry}.
+	 * @param meterRegistry {@link MeterRegistry} to use for Micrometer metrics.
+	 * @deprecated in favour of
+	 * {@link MicrometerStatsLoadBalancerLifecycle#MicrometerStatsLoadBalancerLifecycle(MeterRegistry, ReactiveLoadBalancer.Factory)}
+	 */
+	@Deprecated(forRemoval = true)
+	public MicrometerStatsLoadBalancerLifecycle(MeterRegistry meterRegistry) {
+		// use default properties when calling deprecated constructor
+		this(meterRegistry, new LoadBalancerClientFactory(new LoadBalancerClientsProperties()));
 	}
 
 	@Override
@@ -85,15 +104,19 @@ public void onStartRequest(Request<Object> request, Response<ServiceInstance> lb
 
 	@Override
 	public void onComplete(CompletionContext<Object, ServiceInstance, Object> completionContext) {
+		ServiceInstance serviceInstance = completionContext.getLoadBalancerResponse().getServer();
+		LoadBalancerProperties properties = serviceInstance != null
+				? loadBalancerFactory.getProperties(serviceInstance.getServiceId())
+				: loadBalancerFactory.getProperties(null);
+		LoadBalancerTags loadBalancerTags = new LoadBalancerTags(properties);
 		long requestFinishedTimestamp = System.nanoTime();
 		if (CompletionContext.Status.DISCARD.equals(completionContext.status())) {
 			Counter.builder("loadbalancer.requests.discard")
-				.tags(buildDiscardedRequestTags(completionContext))
+				.tags(loadBalancerTags.buildDiscardedRequestTags(completionContext))
 				.register(meterRegistry)
 				.increment();
 			return;
 		}
-		ServiceInstance serviceInstance = completionContext.getLoadBalancerResponse().getServer();
 		AtomicLong activeRequestsCounter = activeRequestsPerInstance.get(serviceInstance);
 		if (activeRequestsCounter != null) {
 			activeRequestsCounter.decrementAndGet();
@@ -102,15 +125,15 @@ public void onComplete(CompletionContext<Object, ServiceInstance, Object> comple
 		if (requestHasBeenTimed(loadBalancerRequestContext)) {
 			if (CompletionContext.Status.FAILED.equals(completionContext.status())) {
 				Timer.builder("loadbalancer.requests.failed")
-					.tags(buildFailedRequestTags(completionContext))
+					.tags(loadBalancerTags.buildFailedRequestTags(completionContext))
 					.register(meterRegistry)
 					.record(requestFinishedTimestamp
 							- ((TimedRequestContext) loadBalancerRequestContext).getRequestStartTime(),
 							TimeUnit.NANOSECONDS);
 				return;
 			}
 			Timer.builder("loadbalancer.requests.success")
-				.tags(buildSuccessRequestTags(completionContext))
+				.tags(loadBalancerTags.buildSuccessRequestTags(completionContext))
 				.register(meterRegistry)
 				.record(requestFinishedTimestamp
 						- ((TimedRequestContext) loadBalancerRequestContext).getRequestStartTime(),