feat: support Sentinel flow control for RestClient

spring-cloud-alibaba-examples/pom.xml

@@ -20,6 +20,7 @@
         <module>sentinel-example/sentinel-core-example</module>
         <module>sentinel-example/sentinel-openfeign-example</module>
         <module>sentinel-example/sentinel-resttemplate-example</module>
+        <module>sentinel-example/sentinel-restclient-example</module>
         <module>sentinel-example/sentinel-circuitbreaker-example</module>
         <module>sentinel-example/sentinel-webflux-example</module>
         <module>sentinel-example/sentinel-spring-cloud-gateway-example</module>

spring-cloud-alibaba-examples/sentinel-example/sentinel-restclient-example/pom.xml

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <parent>
+        <groupId>com.alibaba.cloud</groupId>
+        <artifactId>spring-cloud-alibaba-examples</artifactId>
+        <version>${revision}</version>
+        <relativePath>../../pom.xml</relativePath>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+
+    <artifactId>sentinel-restclient-example</artifactId>
+    <name>Spring Cloud Starter Alibaba Sentinel x RestClient - Example</name>
+    <description>Example demonstrating how to use sentinel with RestClient</description>
+    <packaging>jar</packaging>
+
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.alibaba.cloud</groupId>
+            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-deploy-plugin</artifactId>
+                <version>${maven-deploy-plugin.version}</version>
+                <configuration>
+                    <skip>true</skip>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

spring-cloud-alibaba-examples/sentinel-example/sentinel-restclient-example/src/main/java/com/alibaba/cloud/examples/RestClientApplication.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2013-present 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 com.alibaba.cloud.examples;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+/**
+ * Demo application for Sentinel RestClient integration.
+ *
+ * @author QHT
+ */
+@SpringBootApplication
+public class RestClientApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(RestClientApplication.class, args);
+	}
+
+}

spring-cloud-alibaba-examples/sentinel-example/sentinel-restclient-example/src/main/java/com/alibaba/cloud/examples/configuration/RestClientBlockHandler.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2013-present the 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 com.alibaba.cloud.examples.configuration;
+
+import com.alibaba.cloud.sentinel.rest.SentinelClientHttpResponse;
+import com.alibaba.csp.sentinel.slots.block.BlockException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.springframework.http.HttpRequest;
+import org.springframework.http.client.ClientHttpRequestExecution;
+import org.springframework.http.client.ClientHttpResponse;
+
+/**
+ * Block handler, fallback and url cleaner for RestClient.
+ *
+ * @author uuuyuqi
+ */
+public class RestClientBlockHandler {
+
+	private static final Logger log = LoggerFactory.getLogger(RestClientBlockHandler.class);
+
+	/**
+	 * Block handler for flow-control.
+	 * When a request is rate-limited, this handler returns a custom response.
+	 */
+	public static ClientHttpResponse handleBlock(HttpRequest request, byte[] body,
+			ClientHttpRequestExecution execution, BlockException ex) {
+		log.warn("[Customized-RestClientBlockHandler] RestClient blocked by flow control: uri={}, rule={}",
+				request.getURI(), ex.getRule());
+		return new SentinelClientHttpResponse(
+				"[Customized-RestClientBlockHandler] Blocked by flow control: " + ex.getClass().getSimpleName());
+	}
+
+	/**
+	 * Fallback for circuit-breaking (degrade).
+	 * When a downstream service is degraded, this handler returns a fallback response.
+	 */
+	public static ClientHttpResponse handleFallback(HttpRequest request, byte[] body,
+			ClientHttpRequestExecution execution, BlockException ex) {
+		log.warn("[Customized-RestClientBlockHandler] RestClient degraded (circuit open): uri={}, rule={}",
+				request.getURI(), ex.getRule());
+		return new SentinelClientHttpResponse("[Customized-RestClientBlockHandler] Service degraded, please try again later");
+	}
+
+	/**
+	 * URL cleaner to normalize RESTful URLs.
+	 * Prevents resource name explosion for parameterized paths.
+	 */
+	public static String cleanUrl(String url) {
+		// Example: normalize /users/123 to /users/{id}
+		// In this demo, we return the URL as-is since httpbin.org paths are fixed
+		return url;
+	}
+
+}

spring-cloud-alibaba-examples/sentinel-example/sentinel-restclient-example/src/main/java/com/alibaba/cloud/examples/configuration/RestClientConfiguration.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2013-present 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 com.alibaba.cloud.examples.configuration;
+
+import com.alibaba.cloud.sentinel.annotation.SentinelRestClient;
+
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.client.RestClient;
+
+
+@Configuration
+public class RestClientConfiguration {
+
+	@Bean
+	@SentinelRestClient(
+			blockHandler = "handleBlock",
+			blockHandlerClass = RestClientBlockHandler.class,
+			fallback = "handleFallback",
+			fallbackClass = RestClientBlockHandler.class,
+			urlCleaner = "cleanUrl",
+			urlCleanerClass = RestClientBlockHandler.class
+	)
+	public RestClient.Builder restClientBuilder() {
+		return RestClient.builder();
+	}
+
+	@Bean
+	public RestClient restClient(@Qualifier("restClientBuilder") RestClient.Builder builder) {
+		// Use the auto-injected Builder so that the Sentinel interceptor takes effect
+		return builder.build();
+	}
+
+
+
+	@Bean
+	public RestClient.Builder anotherRestClientBuilder() {
+		return RestClient.builder();
+	}
+
+	@Bean
+	public RestClient anotherRestClient(@Qualifier("anotherRestClientBuilder") RestClient.Builder builder) {
+		// Use the auto-injected Builder so that the Sentinel interceptor takes effect
+		return builder.build();
+	}
+}

spring-cloud-alibaba-examples/sentinel-example/sentinel-restclient-example/src/main/java/com/alibaba/cloud/examples/configuration/SentinelRulesConfiguration.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2013-present 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 com.alibaba.cloud.examples.configuration;
+
+import java.util.Arrays;
+
+import com.alibaba.csp.sentinel.slots.block.RuleConstant;
+import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRule;
+import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRuleManager;
+import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
+import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
+import jakarta.annotation.PostConstruct;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Programmatic Sentinel rule configuration for the RestClient demo.
+ *
+ * @author QHT
+ */
+@Configuration
+public class SentinelRulesConfiguration {
+
+	private static final Logger log = LoggerFactory.getLogger(SentinelRulesConfiguration.class);
+
+	@PostConstruct
+	public void init() {
+		log.info("Loading Sentinel rules...");
+
+		// Flow rules
+		FlowRule getRule = new FlowRule("GET:https://httpbin.org/get");
+		getRule.setGrade(RuleConstant.FLOW_GRADE_QPS);
+		getRule.setCount(1);
+		getRule.setLimitApp("default");
+
+		FlowRule expRule = new FlowRule("GET:https://httpbin.org/status/500");
+		expRule.setGrade(RuleConstant.FLOW_GRADE_QPS);
+		expRule.setCount(1000);
+		expRule.setLimitApp("default");
+
+		FlowRule rtRule = new FlowRule("GET:https://httpbin.org/delay/3");
+		rtRule.setGrade(RuleConstant.FLOW_GRADE_QPS);
+		rtRule.setCount(1000);
+		rtRule.setLimitApp("default");
+
+		FlowRuleManager.loadRules(Arrays.asList(getRule, expRule, rtRule));
+
+		// Degrade rules
+		DegradeRule degradeRule1 = new DegradeRule("GET:https://httpbin.org/status/500");
+		degradeRule1.setGrade(RuleConstant.DEGRADE_GRADE_EXCEPTION_RATIO);
+		degradeRule1.setCount(0.99); // value "1" is not supported now, see: https://github.com/alibaba/Sentinel/pull/1857
+		degradeRule1.setMinRequestAmount(1);
+		degradeRule1.setStatIntervalMs(10 * 1000);
+		degradeRule1.setTimeWindow(30);
+		degradeRule1.setLimitApp("default");
+
+		DegradeRule degradeRule2 = new DegradeRule("GET:https://httpbin.org/delay/3");
+		degradeRule2.setGrade(RuleConstant.DEGRADE_GRADE_RT);
+		degradeRule2.setCount(2000);
+		degradeRule1.setStatIntervalMs(10 * 1000);
+		degradeRule2.setSlowRatioThreshold(0.1);
+		degradeRule2.setMinRequestAmount(1);
+		degradeRule2.setTimeWindow(30);
+		degradeRule2.setLimitApp("default");
+
+		DegradeRuleManager.loadRules(Arrays.asList(degradeRule1, degradeRule2));
+
+		log.info("Sentinel rules loaded successfully.");
+	}
+
+}