SpringCloud 融入 Python - Flask

前言

该篇文章分享如何将Python Web服务融入到Spring Cloud微服务体系中，并调用其服务，Python Web框架用的是Flask

方案

Sidecar+ Flask，在这里，我们会使用Sidecar将Python接口注册到SpringCloud中，将Python接口当作Java接口进行调用（通过SpringCloud去调用Sidecar，然后通过Sidecar去转发我们的程序请求）

• Sidecar是SpringCloud提供的一个可将第三方的rest接口集成到SpringCloud中的工具

Python服务

• manage.py

import json
from flask import Flask, Response, request, make_response, jsonify

app = Flask(__name__)

@app.route("/health")
def health():
    result = {'status': 'UP'}
    return Response(json.dumps(result), mimetype='application/json')

@app.route("/getUser")
def getUser():
    result = {'username': 'python', 'password': 'python'}
    return Response(json.dumps(result), mimetype='application/json')

@app.errorhandler(404)
def not_found(error):
    return make_response(jsonify({'error': 'Not found'}), 404)

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=3000)

大致说下上述代码，Python服务监听3000端口，health方法用于给Sidecar提供健康接口，用于实时向Sidecar提供自己的健康状态，getUser是Python向外界提供的服务

• 运行方式

python manage.py runserver

sidecar工程

• 添加依赖

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-netflix-sidecar</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

• SidecarApplication.java

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.sidecar.EnableSidecar;

@EnableSidecar
@SpringBootApplication
public class SidecarApplication {

    public static void main(String[] args) {
        SpringApplication.run(SidecarApplication.class, args);
    }
}

• application.yml

spring:
  profiles:
    active: "dev"
  application:
    name: demo-sidecar
    
sidecar:
   port: 3000
   health-uri: http://localhost:${sidecar.port}/health
   
ribbon:
   ConnectTimeout: 50000
   ReadTimeout: 50000
   
hystrix:
   command:
      default:
         execution:
            isolation:
               thread:
                  timeoutInMilliseconds: 10000
    
server:
  port: 8326

eureka:
  client:
    healthcheck:
      enabled: true
    service-url:
      defaultZone: http://${registry.host:localhost}:${registry.port:8761}/eureka/

registry:
  host: localhost
  port: 31091

大致说下上述代码，main方法要使用@EnableSidecar注解，sidecar port代表监听Python运行的端口，server port代表Sidecar运行的端口，spring application name代表Sidecar的服务名，sidecar health-uri是Python健康接口，指向python的健康服务

服务调用 - DemoServer工程(端口8325)

调用方式一 : RestTemplate

• DemoServerApplication.java

@SpringBootApplication
public class DemoServerApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoServerApplication.class, args);
    }
    
    @Bean
    @LoadBalanced
    RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

• RestTemplateController.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class RestTemplateController {
    @Autowired
    private RestTemplate restTemplate;
    @RequestMapping("/java-user")
    public String JavaUser() {
        return "{'username': 'java', 'password': 'java'}"  ;
    }

    @RequestMapping("/python-user")
    public String PythonUser() {
        return restTemplate.getForEntity("http://demo-sidecar/getUser", String.class).getBody();
//      return restTemplate.getForEntity("http://localhost:3000/getUser", String.class).getBody();
    }
}

• 这里做下说明，@LoadBalanced用于开启负载均衡，在这里有两种调用方式，使用和不使用@LoadBalanced
• 使用@LoadBalanced注解后，RestTemplate可以直接调用服务名

@Bean
@LoadBalanced
RestTemplate restTemplate() {
    return new RestTemplate();
}
++++++++++++++++++++++++++++++
return restTemplate.getForEntity("http://demo-sidecar/getUser", String.class).getBody();

• 不使用@LoadBalanced注解，RestTemplate调用的就是固定的IP+PORT

@Bean
// @LoadBalanced
RestTemplate restTemplate() {
    return new RestTemplate();
}
++++++++++++++++++++++++++++++
return restTemplate.getForEntity("http://localhost:3000/getUser", String.class).getBody();

• 服务的启动顺序：Python服务，注册中心，sidecar工程，DemoServer工程
• 运行结果
  
  

调用方式二: Feign

• congfig类中需添加注解@EnableFeignClients，具体使用请百度
• SidecarController.java

@RestController
public class SidecarController {
    private SidecarAPIClient sidecarAPIClient;
    
    @Autowired
    public SidecarController(SidecarAPIClient sidecarAPIClient) {
        this.sidecarAPIClient = sidecarAPIClient;
    }
    
    @GetMapping("/getUser")
    public Object getUser() {
        return this.sidecarAPIClient.getUser();
    }
}

• SidecarAPIClient.java

@FeignClient(name="demo-sidecar", configuration = FeignConfigure.class)
public interface SidecarAPIClient {

    @GetMapping("/getUser")
    Object getUser();
}

• FeignConfigure.java

import feign.Logger;
import feign.codec.Encoder;
import feign.form.spring.SpringFormEncoder;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.web.HttpMessageConverters;
import org.springframework.cloud.netflix.feign.support.SpringEncoder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class FeignConfigure {
    @Bean
    Logger.Level feignLoggerLevel() {
        return Logger.Level.FULL;
    }

    @Autowired
    private ObjectFactory<HttpMessageConverters> messageConverters;
   
    @Bean
    public Encoder feignFormEncoder() {
        return new SpringFormEncoder(new SpringEncoder(messageConverters));
    }
}

• 服务的启动顺序：Python服务，注册中心，sidecar工程，DemoServer工程
• 调用结果
  
  至此，已完成微服务调用Python Web服务

Sidecar总结

• Sidecar是一个用于监听非JVM应用程序(可以是Python或者Node或者Php等等)的一个工具，通过Sidecar可以实现Java和第三方应用程序的双向交互
• 第三方应用程序必须要实现一个接口，实时向Sidecar报告自己的状态，告诉Sidecar自己还在运行着。
• Sidecar应用程序必须和第三方应用程序运行在同一台电脑上，也就是说他们之间是localhost，不能是IP访问

参考博客

SpringCloud 整合Python 感谢大佬

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