connect the web resource in a simple way with the policy engine

Author: purbon

cli/pom.xml

@@ -7,11 +7,13 @@
     <artifactId>capua</artifactId>
     <version>0.0.1</version>
   </parent>
+
   <groupId>com.purbon.kafka.policy</groupId>
   <artifactId>cli</artifactId>
   <version>0.0.1</version>
   <name>cli</name>
   <url>http://maven.apache.org</url>
+
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>

web/pom.xml

@@ -17,6 +17,7 @@
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <spring.boot.version>2.7.4</spring.boot.version>
+    <start-class>com.purbon.kafka.policy.webapi.WebapiApplication</start-class>
   </properties>
 
   <dependencyManagement>
@@ -36,6 +37,15 @@
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-web</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.springframework</groupId>
+      <artifactId>spring-webmvc</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>com.purbon.kafka.policy</groupId>
+      <artifactId>core</artifactId>
+      <version>0.0.1</version>
+    </dependency>
     <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-test</artifactId>
@@ -54,7 +64,19 @@
       <plugin>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-maven-plugin</artifactId>
+        <version>${spring.boot.version}</version>
+        <configuration>
+          <mainClass>com.purbon.kafka.policy.webapi.WebapiApplication</mainClass>
+        </configuration>
+        <executions>
+          <execution>
+            <goals>
+              <goal>repackage</goal>
+            </goals>
+          </execution>
+        </executions>
       </plugin>
+
     </plugins>
   </build>
 

web/src/main/java/com/purbon/kafka/policy/webapi/Utils.java

@@ -0,0 +1,24 @@
+package com.purbon.kafka.policy.webapi;
+
+import java.io.BufferedReader;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.stream.Collectors;
+
+public class Utils {
+
+    public static String getResourceFileAsString(String fileName) {
+        InputStream is = getResourceFileAsInputStream(fileName);
+        if (is != null) {
+            BufferedReader reader = new BufferedReader(new InputStreamReader(is));
+            return (String)reader.lines().collect(Collectors.joining(System.lineSeparator()));
+        } else {
+            throw new RuntimeException("resource not found");
+        }
+    }
+
+    public static InputStream getResourceFileAsInputStream(String fileName) {
+        ClassLoader classLoader = Utils.class.getClassLoader();
+        return classLoader.getResourceAsStream(fileName);
+    }
+}

web/src/main/java/com/purbon/kafka/policy/webapi/WebapiApplication.java

@@ -2,6 +2,7 @@
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.web.servlet.config.annotation.EnableWebMvc;
 
 @SpringBootApplication
 public class WebapiApplication {

web/src/main/java/com/purbon/kafka/policy/webapi/controller/RestPolicyController.java

@@ -0,0 +1,23 @@
+package com.purbon.kafka.policy.webapi.controller;
+
+import com.purbon.kafka.policy.VerifyResult;
+import com.purbon.kafka.policy.webapi.service.KafkaPolicyService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/policy")
+public class RestPolicyController {
+
+    @Autowired
+    KafkaPolicyService service;
+
+    @PostMapping(value = "/validate", consumes = "application/json")
+    public VerifyResult validate(@RequestBody String content) {
+        VerifyResult vr = service.validate(content);
+        return vr;
+    }
+}

web/src/main/java/com/purbon/kafka/policy/webapi/service/KafkaPolicyService.java

@@ -0,0 +1,21 @@
+package com.purbon.kafka.policy.webapi.service;
+
+import com.purbon.kafka.policy.KafkaPolicyEngine;
+import com.purbon.kafka.policy.VerifyResult;
+import com.purbon.kafka.policy.webapi.Utils;
+import org.springframework.stereotype.Service;
+
+@Service
+public class KafkaPolicyService {
+
+    private KafkaPolicyEngine engine;
+
+    public KafkaPolicyService() {
+        engine = KafkaPolicyEngine.getInstance();
+        engine.init(Utils.getResourceFileAsString("kafka-policy.rego"));
+    }
+
+    public VerifyResult validate(String content) {
+        return engine.validate(content);
+    }
+}

web/src/main/resources/kafka-policy.rego

@@ -0,0 +1,11 @@
+package kafka
+
+allow {
+    topic.partitions == 3
+    topic.replicationFactor == 1
+    startswith(topic.name, "foo")
+}
+
+deny {
+    startswith(topic.name, "foo")
+}

web/validate.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+curl --header "Content-Type: application/json" \
+  --request POST \
+  --data '{ "topics": [{ "name": "foo", "partitions": 3, "replicationFactor": 1, "config": {} }]}' \
+  http://localhost:8080/policy/validate