SpringCloud

11.SpringCloud学习笔记

Consul

Posted by Chen Xingxu on August 16, 2020

11.SpringCloud学习笔记–Consul

Consul简介

是什么

Consul is a service mesh solution providing a full featured control plane with service discovery, configuration, and segmentation functionality. Each of these features can be used individually as needed, or they can be used together to build a full service mesh. Consul requires a data plane and supports both a proxy and native integration model. Consul ships with a simple built-in proxy so that everything works out of the box, but also supports 3rd party proxy integrations such as Envoy.

参考：https://www.consul.io/intro

能干嘛

The key features of Consul are:

  • Service Discovery: Clients of Consul can register a service, such as api or mysql, and other clients can use Consul to discover providers of a given service. Using either DNS or HTTP, applications can easily find the services they depend upon.
  • Health Checking: Consul clients can provide any number of health checks, either associated with a given service (“is the webserver returning 200 OK”), or with the local node (“is memory utilization below 90%”). This information can be used by an operator to monitor cluster health, and it is used by the service discovery components to route traffic away from unhealthy hosts.
  • KV Store: Applications can make use of Consul’s hierarchical key/value store for any number of purposes, including dynamic configuration, feature flagging, coordination, leader election, and more. The simple HTTP API makes it easy to use.
  • Secure Service Communication: Consul can generate and distribute TLS certificates for services to establish mutual TLS connections. Intentions can be used to define which services are allowed to communicate. Service segmentation can be easily managed with intentions that can be changed in real time instead of using complex network topologies and static firewall rules.
  • Multi Datacenter: Consul supports multiple datacenters out of the box. This means users of Consul do not have to worry about building additional layers of abstraction to grow to multiple regions.

参考：https://www.consul.io/intro

去哪下

https://www.consul.io/downloads

怎么玩

https://www.springcloud.cc/spring-cloud-consul.html

https://www.consul.io/docs/agent/options.html

https://learn.hashicorp.com/consul/day-0/containers-guide

https://www.consul.io/docs/agent/options.html#_bind

安装并运行Consul

https://learn.hashicorp.com/consul/getting-started/install.html

在windows下运行

consul agent -dev

在 Docker 中安装及运行

docker 拉取 consul 镜像

docker pull consul:1.6

启动 server

启动前, 先建立 /data/consul 文件夹, 保存 consul 的数据

mkdir -p /data/consul

使用 docker run 启动 server

docker run -d -p 8500:8500 -v /data/consul:/consul/data -e CONSUL_BIND_INTERFACE='eth0' --name=consul1 consul:1.6 agent -server -bootstrap -ui -client='0.0.0.0'
  • agent: 表示启动 agent 进程
  • server: 表示 consul 为 server 模式
  • client: 表示 consul 为 client 模式
  • bootstrap: 表示这个节点是 Server-Leader
  • ui: 启动 Web UI, 默认端口 8500
  • node: 指定节点名称, 集群中节点名称唯一
  • client: 绑定客户端接口地址, 0.0.0.0 表示所有地址都可以访问

一般第一个容器的ip地址是 172.17.0.2，可以通过下面的命令查询容器ip：

docker inspect --format '' consul1

往集群插入其他节点

docker run -d --name=consul2 -e CONSUL_BIND_INTERFACE=eth0 consul agent --server=true --client=0.0.0.0 --join 172.17.0.2;
docker run -d --name=consul3 -e CONSUL_BIND_INTERFACE=eth0 consul agent --server=true --client=0.0.0.0 --join 172.17.0.2;
docker run -d --name=consul4 -e CONSUL_BIND_INTERFACE=eth0 consul agent --server=false --client=0.0.0.0 --join 172.17.0.2;
  • join: 表示加入到指定集群中

查看集群下面的节点

docker exec -it consul1 consul members

至此 consul 的部署已经完成。

上述只搭建了dc1，下面开始搭建dc2，并将dc1和dc2关联起来

docker run -d --name=consul5 -e CONSUL_BIND_INTERFACE='eth0' consul agent -server -bootstrap-expect 3 -datacenter=dc2

往dc2添加节点

docker run -d --name=consul6 -e CONSUL_BIND_INTERFACE=eth0 consul agent --datacenter=dc2 --server=true --client=0.0.0.0 --join 172.17.0.6;
docker run -d --name=consul7 -e CONSUL_BIND_INTERFACE=eth0 consul agent --datacenter=dc2 --server=true --client=0.0.0.0 --join 172.17.0.6;
docker run -d --name=consul8 -e CONSUL_BIND_INTERFACE=eth0 consul agent --datacenter=dc2 --server=false --client=0.0.0.0 --join 172.17.0.6;

关联dc1和dc2

docker exec -it consul6 consul join -wan 172.17.0.2

至此可以在web ui看到dc1和dc2！

参考：https://www.jianshu.com/p/df3ef9a4f456

访问consul的web ui

http://192.168.25.157:8500/

服务提供者注册进Consul

1、建module

cloud-providerconsul-payment8006

2、改pom

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>cloud2020</artifactId>
        <groupId>demo.yangxu.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-providerconsul-payment8006</artifactId>

    <dependencies>
        <!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
        <dependency>
            <groupId>demo.yangxu.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <!--SpringCloud consul-server -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-consul-discovery</artifactId>
        </dependency>
        <!-- SpringBoot整合Web组件 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!--日常通用jar包配置-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>RELEASE</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>RELEASE</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

</project>

3、写yml

###consul服务端口号
server:
  port: 8006

spring:
  application:
    name: consul-provider-payment
  ####consul注册中心地址
  cloud:
    consul:
      host: 192.168.25.157
      port: 8500
      discovery:
        health-check-url: http://${spring.cloud.client.ip-address}:${server.port}/actuator/health
        prefer-ip-address: true
        #hostname: 127.0.0.1
        service-name: ${spring.application.name}

4、主启动类

package demo.yangxu.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class PaymentMain8006 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain8006.class,args);
    }
}

5、业务层

Controller

demo.yangxu.springcloud.controller.PaymentController

package demo.yangxu.springcloud.controller;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.UUID;

@RestController
@Slf4j
public class PaymentController {

    @Value("${server.port}")
    private String serverPort;

    @RequestMapping(value = "/payment/consul")
    public String paymentConsul(){
        return "springcloud with consul: "+serverPort+"\t   "+ UUID.randomUUID().toString();
    }
}

6、验证测试

http://192.168.25.157:8500/

http://localhost:8006/payment/consul

springcloud with consul: 8006 81f4242b-c9cf-47da-aa0c-7a68fe9e604a

服务消费者注册进Consul

1、建module

cloud-consumerconsul-order80

2、改pom

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>cloud2020</artifactId>
        <groupId>demo.yangxu.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-consumerconsul-order80</artifactId>

    <dependencies>
        <!--SpringCloud consul-server -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-consul-discovery</artifactId>
        </dependency>
        <!-- SpringBoot整合Web组件 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!--日常通用jar包配置-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

</project>

3、写yml

###consul服务端口号
server:
  port: 80

spring:
  application:
    name: cloud-consumer-order
  ####consul注册中心地址
  cloud:
    consul:
      host: 192.168.25.157
      port: 8500
      discovery:
        health-check-url: http://${spring.cloud.client.ip-address}:${server.port}/actuator/health
        prefer-ip-address: true
        #hostname: 127.0.0.1
        service-name: ${spring.application.name}

4、主启动类

package demo.yangxu.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class OrderConsulMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderConsulMain80.class,args);
    }
}

5、业务层

配置Bean

demo.yangxu.springcloud.config.ApplicationContextConfig

package demo.yangxu.springcloud.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class ApplicationContextConfig {

    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }
}

Controller

demo.yangxu.springcloud.controller.OrderConsulController

package demo.yangxu.springcloud.controller;

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;

@RestController
@Slf4j
public class OrderConsulController {
    public static final String INVOKE_URL = "http://consul-provider-payment";

    @Resource
    private RestTemplate restTemplate;

    @GetMapping(value = "/consumer/payment/consul")
    public String paymentInfo(){
        String result = restTemplate.getForObject(INVOKE_URL+"/payment/consul",String.class);
        return result;
    }
}

6、验证测试

http://192.168.25.157:8500/

http://localhost/consumer/payment/consul

springcloud with consul: 8006 aa2845a5-ed98-405d-a32d-88337459dda4

三个注册中心异同点

组件名 语言 CAP 服务健康检查 对外暴露接口 SpringCloud 集成
Eureka Java AP 可配支持 HTTP 支持
Consul Go CP 支持 HTTP/DNS 支持
Zookeeper Java CP 支持 客户端 支持

CAP Theorem

什么是 CAP？

  • C：Consistency（强一致性）
  • A：Availability（可用性）
  • P：Partition tolerance（分区容错性）

最多只能同时较好的满足两个

CAP 理论的核心是：一个分布式系统不可能同时很好的满足一致性、可用性、分区容错性这三个需求，因此，根据 CAP 原理将 NoSQL 数据库分成了满足 CA 原则、满足 CP 原则和满足 AP 原则三大类：

  • CA：单点集群，满足一致性，可用性的系统，通常在可扩展性上不太强大
  • CP：满足一致性，分区容忍性的系统，通常性能不是特别高
  • AP：满足可用性，分区容忍性的系统，通常可能对一致性要求低一些

CAP 理论关注粒度是数据，而不是整个系统设计的策略

AP 架构

当网络分区出现后，为了保证可用性，系统 B 可以返回旧值，保证系统的可用性

结论：违背了一致性 C 的要求，只满足可用性和分区容错，即 AP

CP 架构

当网络分区出现后，为了保证一致性，就必须拒接请求，否则无法保证一致性

结论：违背了可用性 A 的要求，只满足一致性和分区容错，即 AP

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