.NET Core微服务三:polly熔断与降级
本文的项目代码,在文章结尾处可以下载。
本文使用的环境:Windows10 64位 + VS 2019 + .NET Core 3.1
Consul有关介绍:https://www.jianshu.com/p/32dc52f28a14
Consul官方网址:https://www.consul.io/
一、安装Consul
1.官网下载对应版本,并解压出来
2.打开cmd,cd到解压的目录,运行如下其中一条命令
本次演示都在同一台计算机上,所以本文选择命令一;这两条命令请在开发环境使用,生产环境不要使用。
命令一:“consul.exe agent -dev”服务中心的ip地址,将会使用127.0.0.1
命令二:“consul.exe agent -dev -client x.x.x.x”指定服务中心的ip地址
3.命令运行成功后,打开“http://127.0.0.1:8500/”,出现如下画面
二、创建服务
1.服务端项目大体结构:
2.新建.NET Core类库项目,命名为“ClassLibrary”,然后NuGet搜索并安装
“Consul”、“Microsoft.Extensions.Configuration”、“Microsoft.Extensions.Configuration.Json”
Common.cs代码:
1 using Consul; 2 using Microsoft.Extensions.Configuration; 3 using System; 4 5 namespace ClassLibrary 6 { 7 public class Common 8 { 9 public static IConfiguration Configuration { get; } 10 static Common() 11 { 12 Configuration = new ConfigurationBuilder().AddJsonFile("appsettings.json", false, true).Build(); 13 } 14 15 /// <summary> 16 /// 需要注册的服务地址 17 /// </summary> 18 public static string ConsulServiceIP 19 { 20 get 21 { 22 return Configuration["Consul:ServiceIP"]; 23 } 24 } 25 26 /// <summary> 27 /// 需要注册的服务端口 28 /// </summary> 29 public static int ConsulServicePort 30 { 31 get 32 { 33 string str = Configuration["Consul:ServicePort"]; 34 return int.Parse(str); 35 } 36 } 37 38 /// <summary> 39 /// 服务注册 40 /// </summary> 41 public static void ConsulRegister() 42 { 43 ConsulClient client = new ConsulClient( 44 (ConsulClientConfiguration c) => 45 { 46 c.Address = new Uri(Configuration["Consul:Address"]); //Consul服务中心地址 47 c.Datacenter = Configuration["Consul:DataCenter"]; //指定数据中心,如果未提供,则默认为代理的数据中心。 48 } 49 ); 50 string checkUrl = Configuration["Consul:CheckUrl"]; 51 client.Agent.ServiceRegister(new AgentServiceRegistration() 52 { 53 ID = Guid.NewGuid().ToString(), //服务编号,不可重复 54 Name = Configuration["Consul:ServiceName"], //服务名称 55 Port = ConsulServicePort, //本程序的端口号 56 Address = ConsulServiceIP, //本程序的IP地址 57 Check = new AgentServiceCheck() 58 { 59 DeregisterCriticalServiceAfter = TimeSpan.FromMilliseconds(1), //服务停止后多久注销 60 Interval = TimeSpan.FromSeconds(5), //服务健康检查间隔 61 Timeout = TimeSpan.FromSeconds(5), //检查超时的时间 62 HTTP = $"http://{ConsulServiceIP}:{ConsulServicePort}{checkUrl}" //检查的地址 63 } 64 }); 65 } 66 67 } 68 }
3.新建.NET Core的webapi项目,命名为“ServiceStudent”,把“为HTTPS配置”的勾选去掉
Controller代码:
1 using Microsoft.AspNetCore.Mvc;
2 using System;
3 using System.Collections.Generic;
4
5 namespace ServiceStudent.Controllers
6 {
7 [Route("api/[controller]/[action]")]
8 [ApiController]
9 public class DefaultController : ControllerBase
10 {
11 static List<Student> list = new List<Student>() {
12 new Student(){ ID = "001", StudentName = "学生1", StudentAge = 16 },
13 new Student(){ ID = "002", StudentName = "学生2", StudentAge = 18 },
14 new Student(){ ID = "003", StudentName = "学生3", StudentAge = 17 }
15 };
16
17 /// <summary>
18 /// 健康检查接口
19 /// </summary>
20 [HttpGet]
21 public string Check()
22 {
23 return "1";
24 }
25
26 [HttpGet]
27 public List<Student> GetList()
28 {
29 Console.WriteLine(DateTime.Now.ToString());
30 return list;
31 }
32
33 [HttpGet]
34 public Student GetModel(string id)
35 {
36 Console.WriteLine(DateTime.Now.ToString());
37 return list.Find(t => t.ID == id);
38 }
39 }
40 }
其中有一段健康检查的接口,作用是让服务中心知道服务没有挂掉还能访问,不需要什么业务,所以怎么简单怎么来:
Model代码:
public class Student
{
public string ID { get; set; }
public string StudentName { get; set; }
public int StudentAge { get; set; }
}
appsettings.json的配置,加入"Consul",注意ServiceIP改为自己电脑的IP(这个不要配置为127.0.0.1,后面访问会不正常)
1 { 2 "Logging": { 3 "LogLevel": { 4 "Default": "Information", 5 "Microsoft": "Warning", 6 "Microsoft.Hosting.Lifetime": "Information" 7 } 8 }, 9 "AllowedHosts": "*", 10 "Consul": { 11 "Address": "http://127.0.0.1:8500", 12 "CheckUrl": "/api/Default/Check", 13 "DataCenter": "dc1", 14 "ServiceIP": "192.168.2.119", 15 "ServicePort": 551, 16 "ServiceName": "Student" 17 } 18 }
Program.cs的CreateHostBuilder方法改为:
1 public static IHostBuilder CreateHostBuilder(string[] args) => 2 Host.CreateDefaultBuilder(args) 3 .ConfigureWebHostDefaults(webBuilder => 4 { 5 string ip = Common.ConsulServiceIP; 6 int port = Common.ConsulServicePort; 7 webBuilder.UseStartup<Startup>().UseUrls($"http://{ip}:{port}"); 8 });
在Startup.cs的Configure方法中加入“ClassLibrary.Common.ConsulRegister();”
这样一个“Student”服务就创建好了,“Teacher”服务也是如法炮制,但是需要改appsettings.json的服务名和端口号,代码就不贴了,请到文章结尾处下载。
三、启动服务
通过命令行来启动,打开cmd,cd到Debug目录,各自运行“dotnet ServiceStudent.dll”和“dotnet ServiceTeacher.dll”。
请检查端口有没有被占用或超出范围,如果失败了,在配置文件中换成其它端口试试。
服务运行成功后,打开“http://127.0.0.1:8500/”,如下画面注册成功
如果出现一项打X,那就是失败,这个服务会在1分钟之后被踢出列表
一个服务可能会部署到多个服务器上,用“Teacher”来模拟下多台机器运行。
前面运行好的服务不要关闭,打开Teacher的Debug目录下的配置文件,
修改它的端口号,服务名不用改,再新开一个cmd,运行“dotnet ServiceTeacher.dll”
那么服务中心就会有变化
四、使用服务
1.客户端项目大体结构:
2.新建.net core类库项目,命名为“ClassLibrary”,然后NuGet搜索并安装
“Consul”、“Microsoft.Extensions.Configuration”
Common.cs代码:
using Consul;
using Microsoft.Extensions.Configuration;
using System;
using System.Linq;
using System.Net.Http;
using System.Threading.Tasks;
namespace ClassLibrary
{
public class Common
{
public static IConfiguration Configuration { get; }
static Common()
{
Configuration = new ConfigurationBuilder().AddJsonFile("appsettings.json", false, true).Build();
}
public static string ConsulAddress
{
get { return Configuration["ConsulAddress"]; }
}
/// <summary>
/// 获取服务
/// </summary>
public static string GetService(string serviceName)
{
ConsulClient client = new ConsulClient(c => c.Address = new Uri(ConsulAddress));
var response = client.Agent.Services().Result.Response;
//服务名称区分大小写,若要不区分:Equals(serviceName, StringComparison.OrdinalIgnoreCase)
var services = response.Where(s => s.Value.Service.Equals(serviceName)).Select(s => s.Value);
//进行取模,随机取得一个服务器,或者使用其它负载均衡策略
var service = services.ElementAt(Environment.TickCount % services.Count());
return service.Address + ":" + service.Port;
}
/// <summary>
/// 获取服务(异步方法)
/// </summary>
public async Task<string> GetService2(string serviceName)
{
ConsulClient client = new ConsulClient(c => c.Address = new Uri(ConsulAddress));
var response = (await client.Agent.Services()).Response;
//服务名称区分大小写,若要不区分:Equals(serviceName, StringComparison.OrdinalIgnoreCase)
var services = response.Where(s => s.Value.Service.Equals(serviceName)).Select(s => s.Value);
//进行取模,随机取得一个服务器,或者使用其它负载均衡策略
var service = services.ElementAt(Environment.TickCount % services.Count());
return service.Address + ":" + service.Port;
}
public static string HttpGetString(string url)
{
HttpClient httpClient = new HttpClient();
string result = httpClient.GetAsync(url)
.Result.Content.ReadAsStringAsync().Result;
httpClient.Dispose();
return result;
}
public static T HttpGetObject<T>(string url)
{
string result = HttpGetString(url);
return Newtonsoft.Json.JsonConvert.DeserializeObject<T>(result);
}
}
}
3.新建.NET Core的webapi项目,命名为“ClientSite”,把“为HTTPS配置”的勾选去掉
StudentController代码:
1 using ClassLibrary;
2 using Microsoft.AspNetCore.Mvc;
3 using System.Collections.Generic;
4
5 namespace ClientSite.Controllers
6 {
7 [Route("api/[controller]/[action]")]
8 [ApiController]
9 public class StudentController : ControllerBase
10 {
11 [HttpGet]
12 public object GetList()
13 {
14 string ip = Common.GetService("Student");
15 List<Student> list = Common.HttpGetObject<List<Student>>($"http://{ip}/api/Default/GetList");
16 return new
17 {
18 address = ip,
19 data = list
20 };
21 }
22
23 [HttpGet]
24 public object GetModel(string id)
25 {
26 string ip = Common.GetService("Student");
27 Student model = Common.HttpGetObject<Student>($"http://{ip}/api/Default/GetModel?id={id}");
28 return new
29 {
30 address = ip,
31 data = model
32 };
33 }
34 }
35 }
TeacherController代码:
1 using ClassLibrary;
2 using Microsoft.AspNetCore.Mvc;
3 using System.Collections.Generic;
4
5 namespace ClientSite.Controllers
6 {
7 [Route("api/[controller]/[action]")]
8 [ApiController]
9 public class TeacherController : ControllerBase
10 {
11 [HttpGet]
12 public object GetList()
13 {
14 string ip = Common.GetService("Teacher");
15 List<Teacher> list = Common.HttpGetObject<List<Teacher>>($"http://{ip}/api/Default/GetList");
16 return new
17 {
18 address = ip,
19 data = list
20 };
21 }
22
23 [HttpGet]
24 public object GetModel(string id)
25 {
26 string ip = Common.GetService("Teacher");
27 Teacher model = Common.HttpGetObject<Teacher>($"http://{ip}/api/Default/GetModel?id={id}");
28 return new
29 {
30 address = ip,
31 data = model
32 };
33 }
34 }
35 }
appsettings.json加入:
"ConsulAddress": "http://127.0.0.1:8500"
4.用VS启动站点,然后用postman访问
“http://ip:port/api/Student/GetList”
“http://ip:port/api/Student/GetModel?id=002”
多次访问“http://ip:port/api/Teacher/GetList”,则address会随机切换,注意看返回的端口号