Consul是一个用来实现分布式系统服务发现与配置的开源工具。它内置了服务注册与发现框架、分布一致性协议实现、健康检查、Key/Value存储、多数据中心方案，不再需要依赖其他工具，使用起来也较为简单。
Consul官网：https://www.consul.io
开源地址：https://github.com/hashicorp/consul、https://github.com/G-Research/consuldotnet
安装
Consul支持各种平台的安装，安装文档：https://www.consul.io/downloads，为了快速使用，我这里选择用docker方式安装。
version: "3"
services:
service_1:
image: consul
command: agent -server -client=0.0.0.0 -bootstrap-expect=3 -node=service_1
volumes:
- /usr/local/docker/consul/data/service_1:/data
service_2:
image: consul
command: agent -server -client=0.0.0.0 -retry-join=service_1 -node=service_2
volumes:
- /usr/local/docker/consul/data/service_2:/data
depends_on:
- service_1
service_3:
image: consul
command: agent -server -client=0.0.0.0 -retry-join=service_1 -node=service_3
volumes:
- /usr/local/docker/consul/data/service_3:/data
depends_on:
- service_1
client_1:
image: consul
command: agent -client=0.0.0.0 -retry-join=service_1 -ui -node=client_1
ports:
- 8500:8500
volumes:
- /usr/local/docker/consul/data/client_1:/data
depends_on:
- service_2
- service_3
提供一个docker-compose.yaml，使用docker-compose up编排脚本启动Consul，如果你不熟悉，可以选择其它方式能运行Consul即可。
这里使用 Docker 搭建 3个 server 节点 + 1 个 client 节点，API 服务通过 client 节点进行服务注册和发现。
安装完成启动Consul，打开默认地址 http://localhost:8500 可以看到Consului界面。
快速使用
添加两个webapi服务，ServiceA和ServiceB，一个webapi客户端Client来调用服务。
dotnet new sln -n consul_demo
dotnet new webapi -n ServiceA
dotnet sln add ServiceA/ServiceA.csproj
dotnet new webapi -n ServiceB
dotnet sln add ServiceB/ServiceB.csproj
dotnet new webapi -n Client
dotnet sln add Client/Client.csproj
在项目中添加Consul组件包
Install-Package Consul
服务注册
接下来在两个服务中添加必要的代码来实现将服务注册到Consul中。
首先将Consul配置信息添加到appsettings.json
{
"Consul": {
"Address": "http://host.docker.internal:8500",
"HealthCheck": "/healthcheck",
"Name": "ServiceA",
"Ip": "host.docker.internal"
}
}
因为我们要将项目都运行在docker中，所以这里的地址要用 host.docker.internal 代替，使用 localhost 无法正常启动，如果不在 docker 中运行，这里就配置层 localhost。
添加一个扩展方法UseConul(this IApplicationBuilder app, IConfiguration configuration, IHostApplicationLifetime lifetime)。
using System;
using Consul;
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
namespace ServiceA
{
public static class Extensions
{
public static IApplicationBuilder UseConul(this IApplicationBuilder app, IConfiguration configuration, IHostApplicationLifetime lifetime)
{
var client = new ConsulClient(options =>
{
options.Address = new Uri(configuration["Consul:Address"]); // Consul客户端地址
});
var registration = new AgentServiceRegistration
{
ID = Guid.NewGuid().ToString(), // 唯一Id
Name = configuration["Consul:Name"], // 服务名
Address = configuration["Consul:Ip"], // 服务绑定IP
Port = Convert.ToInt32(configuration["Consul:Port"]), // 服务绑定端口
Check = new AgentServiceCheck
{
DeregisterCriticalServiceAfter = TimeSpan.FromSeconds(5), // 服务启动多久后注册
Interval = TimeSpan.FromSeconds(10), // 健康检查时间间隔
HTTP = $"http://{configuration["Consul:Ip"]}:{configuration["Consul:Port"]}{configuration["Consul:HealthCheck"]}", // 健康检查地址
Timeout = TimeSpan.FromSeconds(5) // 超时时间
}
};
// 注册服务
client.Agent.ServiceRegister(registration).Wait();
// 应用程序终止时，取消服务注册
lifetime.ApplicationStopping.Register(() =>
{
client.Agent.ServiceDeregister(registration.ID).Wait();
});
return app;
}
}
}
然后在Startup.cs中使用扩展方法即可。
public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IHostApplicationLifetime lifetime)
{
...
app.UseConul(Configuration, lifetime);
}
注意，这里将IConfiguration和IHostApplicationLifetime作为参数传进来的，根据实际开发做对应的修改就可以了。
分别在ServiceA和ServiceB都完成一遍上述操作，因为不是实际项目，这里就产生的许多重复代码，在真正的项目开发过程中可以考虑放在一个单独的项目中，ServiceA和ServiceB分别引用，调用。
接着去实现健康检查接口。
// ServiceA
using Microsoft.AspNetCore.Mvc;
namespace ServiceA.Controllers
{
[Route("[controller]")]
[ApiController]
public class HealthCheckController : ControllerBase
{
///
/// 健康检查
///
///
[HttpGet]
public IActionResult api()
{
return Ok();
}
}
}
// ServiceB
using Microsoft.AspNetCore.Mvc;
namespace ServiceB.Controllers
{
[Route("[controller]")]
[ApiController]
public class HealthCheckController : ControllerBase
{
///
/// 健康检查
///
///
[HttpGet]
public IActionResult Get()
{
return Ok();
}
}
}
最后在ServiceA和ServiceB中都添加一个接口。
// ServiceA
using System;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
namespace ServiceA.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class ServiceAController : ControllerBase
{
[HttpGet]
public IActionResult Get([FromServices] IConfiguration configuration)
{
var result = new
{
msg = $"我是{nameof(ServiceA)}，当前时间：{DateTime.Now:G}",
ip = Request.HttpContext.Connection.LocalIpAddress.ToString(),
port = configuration["Consul:Port"]
};
return Ok(result);
}
}
}
// ServiceB
using System;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
namespace ServiceB.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class ServiceBController : ControllerBase
{
[HttpGet]
public IActionResult Get([FromServices] IConfiguration configuration)
{
var result = new
{
msg = $"我是{nameof(ServiceB)}，当前时间：{DateTime.Now:G}",
ip = Request.HttpContext.Connection.LocalIpAddress.ToString(),
port = configuration["Consul:Port"]
};
return Ok(result);
}
}
}
这样我们写了两个服务，ServiceA和ServiceB。都添加了健康检查接口和一个自己的服务接口，返回一段json。
我们现在来运行看看效果，可以使用任何方式，只要能启动即可，我这里选择在docker中运行，直接在 Visual Studio中对着两个解决方案右键添加，选择Docker支持，默认会帮我们自动创建好Dockfile，非常方便。
生成的Dockfile文件内容如下：
# ServiceA
FROM mcr.microsoft.com/dotnet/core/aspnet:3.1-buster-slim AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443
FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster AS build
WORKDIR /src
COPY ["ServiceA/ServiceA.csproj", "ServiceA/"]
RUN dotnet restore "ServiceA/ServiceA.csproj"
COPY . .
WORKDIR "/src/ServiceA"
RUN dotnet build "ServiceA.csproj" -c Release -o /app/build
FROM build AS publish
RUN dotnet publish "ServiceA.csproj" -c Release -o /app/publish
FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "ServiceA.dll"]
# ServiceB
FROM mcr.microsoft.com/dotnet/core/aspnet:3.1-buster-slim AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443
FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster AS build
WORKDIR /src
COPY ["ServiceB/ServiceB.csproj", "ServiceB/"]
RUN dotnet restore "ServiceB/ServiceB.csproj"
COPY . .
WORKDIR "/src/ServiceB"
RUN dotnet build "ServiceB.csproj" -c Release -o /app/build
FROM build AS publish
RUN dotnet publish "ServiceB.csproj" -c Release -o /app/publish
FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "ServiceB.dll"]
然后定位到项目根目录，使用命令去编译两个镜像，service_a和service_b
docker build -t service_a:dev -f ./ServiceA/Dockerfile .
docker build -t service_b:dev -f ./ServiceB/Dockerfile .
看到 Successfully 就成功了，通过docker image ls可以看到我们打包的两个镜像。
这里顺便提一句，已经可以看到我们编译的镜像，service_a和service_b了，但是还有许多名称为
一般来说，虚悬镜像已经失去了存在的价值，是可以随意删除的，可以docker image prune命令删除，这样镜像列表就干净多了。
最后将两个镜像service_a和service_b，分别运行三个实例。
docker run -d -p 5050:80 --name service_a1 service_a:dev --Consul:Port="5050"
docker run -d -p 5051:80 --name service_a2 service_a:dev --Consul:Port="5051"
docker run -d -p 5052:80 --name service_a3 service_a:dev --Consul:Port="5052"
docker run -d -p 5060:80 --name service_b1 service_b:dev --Consul:Port="5060"
docker run -d -p 5061:80 --name service_b2 service_b:dev --Consul:Port="5061"
docker run -d -p 5062:80 --name service_b3 service_b:dev --Consul:Port="5062"
运行成功，接下来就是见证奇迹的时刻，去到Consul看看。
成功将两个服务注册到Consul，并且每个服务都有多个实例。
访问一下接口试试吧，看看能不能成功出现结果。
因为终端编码问题，导致显示乱码，这个不影响，ok，至此服务注册大功告成。
服务发现
搞定了服务注册，接下来演示一下如何服务发现，在Client项目中先将Consul地址配置到appsettings.json中。
{
"Consul": {
"Address": "http://host.docker.internal:8500"
}
}
然后添加一个接口，IService.cs，添加三个方法，分别获取两个服务的返回结果以及初始化服务的方法。
using System.Threading.Tasks;
namespace Client
{
public interface IService
{
///
/// 获取 ServiceA 返回数据
///
///
Task
///
/// 获取 ServiceB 返回数据
///
///
Task
///
/// 初始化服务
///
void InitServices();
}
}
实现类：Service.cs
using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Net.Http;
using System.Threading.Tasks;
using Consul;
using Microsoft.Extensions.Configuration;
namespace Client
{
public class Service : IService
{
private readonly IConfiguration _configuration;
private readonly ConsulClient _consulClient;
private ConcurrentBag
private ConcurrentBag
private IHttpClientFactory _httpClient;
public Service(IConfiguration configuration, IHttpClientFactory httpClient)
{
_configuration = configuration;
_consulClient = new ConsulClient(options =>
{
options.Address = new Uri(_configuration["Consul:Address"]);
});
_httpClient = httpClient;
}
public async Task
{
if (_serviceAUrls == null)
return await Task.FromResult("ServiceA正在初始化...");
using var httpClient = _httpClient.CreateClient();
var serviceUrl = _serviceAUrls.ElementAt(new Random().Next(_serviceAUrls.Count()));
Console.WriteLine("ServiceA：" + serviceUrl);
var result = await httpClient.GetStringAsync($"{serviceUrl}/api/servicea");
return result;
}
public async Task
{
if (_serviceBUrls == null)
return await Task.FromResult("ServiceB正在初始化...");
using var httpClient = _httpClient.CreateClient();
var serviceUrl = _serviceBUrls.ElementAt(new Random().Next(_serviceBUrls.Count()));
Console.WriteLine("ServiceB：" + serviceUrl);
var result = await httpClient.GetStringAsync($"{serviceUrl}/api/serviceb");
return result;
}
public void InitServices()
{
var serviceNames = new string[] { "ServiceA", "ServiceB" };
foreach (var item in serviceNames)
{
Task.Run(async () =>
{
var queryOptions = new QueryOptions
{
WaitTime = TimeSpan.FromMinutes(5)
};
while (true)
{
await InitServicesAsync(queryOptions, item);
}
});
}
async Task InitServicesAsync(QueryOptions queryOptions, string serviceName)
{
var result = await _consulClient.Health.Service(serviceName, null, true, queryOptions);
if (queryOptions.WaitIndex != result.LastIndex)
{
queryOptions.WaitIndex = result.LastIndex;
var services = result.Response.Select(x => $"http://{x.Service.Address}:{x.Service.Port}");
if (serviceName == "ServiceA")
{
_serviceAUrls = new ConcurrentBag
}
else if (serviceName == "ServiceB")
{
_serviceBUrls = new ConcurrentBag
}
}
}
}
}
}
代码就不解释了，相信都可以看懂，使用了Random类随机获取一个服务，关于这点可以选择更合适的负载均衡方式。
在Startup.cs中添加接口依赖注入、使用初始化服务等代码。
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
namespace Client
{
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
public void ConfigureServices(IServiceCollection services)
{
services.AddControllers();
services.AddHttpClient();
services.AddSingleton
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IService service)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
app.UseHttpsRedirection();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllers();
});
service.InitServices();
}
}
}
一切就绪，添加api访问我们的两个服务。
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
namespace Client.Controllers
{
[Route("api")]
[ApiController]
public class HomeController : ControllerBase
{
[HttpGet]
[Route("service_result")]
public async Task
{
return Ok(new
{
serviceA = await service.GetServiceA(),
serviceB = await service.GetServiceB()
});
}
}
}
直接在Visual Studio中运行Client项目，在浏览器访问api。
大功告成，服务注册与发现，现在就算之中的某个节点挂掉，服务也可以照常运行。
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