From 01f5b186a8b0bd61e0fff9aebd5465c1ac4ada40 Mon Sep 17 00:00:00 2001
From: Amit Bhave <amitbhave10@gmail.com>
Date: Sat, 2 Jan 2021 14:49:45 +0530
Subject: [PATCH] BAEL-3636 - introduction to alibaba sentinel

---
 spring-cloud/pom.xml                          |  1 +
 spring-cloud/spring-cloud-sentinel/pom.xml    | 35 +++++++++++++++++++
 .../cloud/sentinel/SentinelApplication.java   | 11 ++++++
 .../config/SentinelAspectConfiguration.java   | 35 +++++++++++++++++++
 .../controller/GreetingController.java        | 19 ++++++++++
 .../sentinel/service/GreetingService.java     | 19 ++++++++++
 6 files changed, 120 insertions(+)
 create mode 100644 spring-cloud/spring-cloud-sentinel/pom.xml
 create mode 100644 spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/SentinelApplication.java
 create mode 100644 spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/config/SentinelAspectConfiguration.java
 create mode 100644 spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/controller/GreetingController.java
 create mode 100644 spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/service/GreetingService.java

diff --git a/spring-cloud/pom.xml b/spring-cloud/pom.xml
index c0e452afaf..efa9df40d9 100644
--- a/spring-cloud/pom.xml
+++ b/spring-cloud/pom.xml
@@ -44,6 +44,7 @@
         <module>spring-cloud-circuit-breaker</module>
         <module>spring-cloud-eureka-self-preservation</module>
         <!--<module>spring-cloud-openfeign</module>--> <!-- Fixing in JAVA-2820 -->
+        <module>spring-cloud-sentinel</module>
     </modules>
 
     <build>
diff --git a/spring-cloud/spring-cloud-sentinel/pom.xml b/spring-cloud/spring-cloud-sentinel/pom.xml
new file mode 100644
index 0000000000..8864baa7b2
--- /dev/null
+++ b/spring-cloud/spring-cloud-sentinel/pom.xml
@@ -0,0 +1,35 @@
+<?xml version="1.0"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <artifactId>spring-cloud-sentinel</artifactId>
+  <name>spring-cloud-sentinel</name>
+  <url>http://maven.apache.org</url>
+  <packaging>pom</packaging>
+  <parent>
+    <groupId>com.baeldung.spring.cloud</groupId>
+    <artifactId>spring-cloud</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
+  </parent>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-web</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.springframework.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>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+</project>
diff --git a/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/SentinelApplication.java b/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/SentinelApplication.java
new file mode 100644
index 0000000000..4459c8374d
--- /dev/null
+++ b/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/SentinelApplication.java
@@ -0,0 +1,11 @@
+package org.spring.cloud.sentinel;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class SentinelApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(SentinelApplication.class, args);
+    }
+}
diff --git a/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/config/SentinelAspectConfiguration.java b/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/config/SentinelAspectConfiguration.java
new file mode 100644
index 0000000000..5241c59527
--- /dev/null
+++ b/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/config/SentinelAspectConfiguration.java
@@ -0,0 +1,35 @@
+package org.spring.cloud.sentinel.config;
+
+import com.alibaba.csp.sentinel.annotation.aspectj.SentinelResourceAspect;
+import com.alibaba.csp.sentinel.slots.block.RuleConstant;
+import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
+import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import javax.annotation.PostConstruct;
+import java.util.ArrayList;
+import java.util.List;
+
+@Configuration
+public class SentinelAspectConfiguration {
+
+    @Bean
+    public SentinelResourceAspect sentinelResourceAspect() {
+        return new SentinelResourceAspect();
+    }
+
+    @PostConstruct
+    public void initFlowRules() {
+        List<FlowRule> flowRules = new ArrayList<>();
+        FlowRule flowRule = new FlowRule();
+        // Defined resource
+        flowRule.setResource("greeting");
+        flowRule.setGrade(RuleConstant.FLOW_GRADE_QPS);
+        // number of requests that QPS can pass in a second
+        flowRule.setCount(1);
+        flowRules.add(flowRule);
+        FlowRuleManager.loadRules(flowRules);
+    }
+
+}
diff --git a/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/controller/GreetingController.java b/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/controller/GreetingController.java
new file mode 100644
index 0000000000..83d68e6444
--- /dev/null
+++ b/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/controller/GreetingController.java
@@ -0,0 +1,19 @@
+package org.spring.cloud.sentinel.controller;
+
+import org.spring.cloud.sentinel.service.GreetingService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class GreetingController {
+
+    @Autowired
+    private GreetingService greetingService;
+
+    @GetMapping("/hello")
+    public String getGreeting() {
+        return greetingService.getGreeting();
+    }
+
+}
diff --git a/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/service/GreetingService.java b/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/service/GreetingService.java
new file mode 100644
index 0000000000..3c45401ca1
--- /dev/null
+++ b/spring-cloud/spring-cloud-sentinel/src/main/java/org/spring/cloud/sentinel/service/GreetingService.java
@@ -0,0 +1,19 @@
+package org.spring.cloud.sentinel.service;
+
+import com.alibaba.csp.sentinel.annotation.SentinelResource;
+import org.springframework.stereotype.Service;
+
+@Service
+public class GreetingService {
+
+    @SentinelResource(value = "greeting", fallback = "getGreetingFallback")
+    public String getGreeting() {
+        return "Hello World!";
+    }
+
+    public String getGreetingFallback(Throwable e) {
+        e.printStackTrace();
+        return "Bye world!";
+    }
+
+}