.NET Core Consul

隨着微服務的流行，為微服務提供支持的各種組件也日益豐富，而Consul就是其中一款常用的服務註冊和發現工具。.NET Core Consul是一套基於.NET Core的API，提供了對Consul註冊中心的簡便訪問，使用.NET Core Consul可以輕鬆地實現服務的註冊、發現和負載均衡等操作。

一、Consul基礎概念介紹

在使用.NET Core Consul前，先對Consul的基礎概念做簡單介紹：

服務註冊：在Consul上註冊服務，Consul會使用心跳機制檢查服務是否健康。
服務發現：通過Consul的服務發現功能，可以實現輕鬆發現和訪問已註冊的服務。
健康檢查：在服務註冊時需要提供服務的健康檢查地址，Consul會通過該地址定時發送檢查請求，以檢查服務的健康狀況。
分布式鎖：Consul提供了分布式鎖，用於處理在分布式環境下的並發操作。
事件處理：Consul提供了事件處理機制，可以在特定的事件觸發時執行預定的操作。

二、與.NET Core集成

使用.NET Core Consul需要先安裝其依賴包——ConsulSharp。

dotnet add package ConsulSharp

然後在Startup.cs文件中進行配置：

services.AddSingleton<ConsulService>();
services.Configure<ConsulConfig>(Configuration.GetSection("ConsulConfig"));

這其中，ConsulConfig用於配置Consul的相關參數，可以在appsettings.json文件中定義：

{
  "ConsulConfig": {
    "Address": "http://localhost:8500",
    "Datacenter": "dc1",
    "Token": ""
  }
}

三、服務註冊

首先定義一個用於服務註冊的接口：

public interface IServiceRegistry
{
    Task<bool> RegisterService(ServiceRegistration registration);
}

其中，ServiceRegistration就是服務註冊的相關信息，包括服務名稱、IP、端口、健康檢查地址等。下面是IServiceRegistry的具體實現：

public class ConsulServiceRegistry : IServiceRegistry
{
    private readonly IConsulClient _consul;
    private readonly ConsulConfig _consulConfig;

    public ConsulServiceRegistry(IOptions<ConsulConfig> consulConfig, IConsulClient consul)
    {
        _consul = consul;
        _consulConfig = consulConfig.Value;
    }

    public async Task<bool> RegisterService(ServiceRegistration registration)
    {
        var registrationRequest = new AgentServiceRegistration
        {
            Name = registration.Name,
            ID = registration.ID,
            Address = registration.Address,
            Port = registration.Port,
            Check = new AgentServiceCheck
            {
                HTTP = registration.HealthCheckURL,
                Interval = TimeSpan.FromSeconds(registration.HealthCheckIntervalSeconds),
                Timeout = TimeSpan.FromSeconds(registration.HealthCheckTimeoutSeconds)
            }
        };
        var result = await _consul.Agent.ServiceRegister(registrationRequest);
        return result.StatusCode == HttpStatusCode.OK;
    }
}

使用IServiceRegistry進行服務註冊：

var registration = new ServiceRegistration
{
    Name = "serviceName",
    ID = "serviceId",
    Address = "localhost",
    Port = 5000,
    HealthCheckIntervalSeconds = 10,
    HealthCheckTimeoutSeconds = 5,
    HealthCheckURL = "http://localhost:5000/health"
};
await _serviceRegistry.RegisterService(registration);

四、服務發現

Consul提供三種服務發現機制：DNS、HTTP和gRPC，其中HTTP方式最為常用，下面以此為例講解。

定義IServiceDiscovery接口：

public interface IServiceDiscovery
{
    Task<List<Uri>> DiscoverServiceUri(string serviceName);
}

ConsulServiceDiscovery的實現：

public class ConsulServiceDiscovery : IServiceDiscovery
{
    private readonly IConsulClient _consul;
    private readonly ConsulConfig _consulConfig;

    public ConsulServiceDiscovery(IOptions<ConsulConfig> consulConfig, IConsulClient consul)
    {
        _consul = consul;
        _consulConfig = consulConfig.Value;
    }

    public async Task<List<Uri>> DiscoverServiceUri(string serviceName)
    {
        var queryResult = await _consul.Catalog.Service(serviceName);
        return queryResult.Response.Select(service => new Uri($"http://{service.ServiceAddress}:{service.ServicePort}/")).ToList();
    }
}

使用IServiceDiscovery進行服務發現：

var serviceUris = await _serviceDiscovery.DiscoverServiceUri("serviceName");

五、負載均衡

對於服務集群，常常需要進行負載均衡，.NET Core Consul提供了兩種負載均衡方式：隨機模式和輪詢模式。

定義IServiceLoadBalancer接口：

public interface IServiceLoadBalancer
{
    Task<Uri> ChooseServer(List<Uri> servers);
}

ConsulServiceLoadBalancer的實現：

public class ConsulServiceLoadBalancer : IServiceLoadBalancer
{
    private readonly ConcurrentDictionary<string, int> _indexDictionary = new ConcurrentDictionary<string, int>();

    public async Task<Uri> ChooseServer(List<Uri> servers)
    {
        var serviceName = servers.First().AbsolutePath.Split('/')[1];
        var index = _indexDictionary.AddOrUpdate(serviceName, 0, (_, i) => (i + 1) % servers.Count);
        return servers[index];
    }
}

使用IServiceLoadBalancer進行負載均衡：

var chosenServer = await _serviceLoadBalancer.ChooseServer(serviceUris);

六、完整示例代碼

以下是一個演示.NET Core Consul的完整示例代碼：

using Consul;
using Microsoft.Extensions.Options;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Threading.Tasks;

namespace Sample
{
    public class ConsulServiceRegistry : IServiceRegistry
    {
        private readonly IConsulClient _consul;
        private readonly ConsulConfig _consulConfig;

        public ConsulServiceRegistry(IOptions<ConsulConfig> consulConfig, IConsulClient consul)
        {
            _consul = consul;
            _consulConfig = consulConfig.Value;
        }

        public async Task<bool> RegisterService(ServiceRegistration registration)
        {
            var registrationRequest = new AgentServiceRegistration
            {
                Name = registration.Name,
                ID = registration.ID,
                Address = registration.Address,
                Port = registration.Port,
                Check = new AgentServiceCheck
                {
                    HTTP = registration.HealthCheckURL,
                    Interval = TimeSpan.FromSeconds(registration.HealthCheckIntervalSeconds),
                    Timeout = TimeSpan.FromSeconds(registration.HealthCheckTimeoutSeconds)
                }
            };
            var result = await _consul.Agent.ServiceRegister(registrationRequest);
            return result.StatusCode == HttpStatusCode.OK;
        }
    }

    public class ConsulServiceDiscovery : IServiceDiscovery
    {
        private readonly IConsulClient _consul;
        private readonly ConsulConfig _consulConfig;

        public ConsulServiceDiscovery(IOptions<ConsulConfig> consulConfig, IConsulClient consul)
        {
            _consul = consul;
            _consulConfig = consulConfig.Value;
        }

        public async Task<List<Uri>> DiscoverServiceUri(string serviceName)
        {
            var queryResult = await _consul.Catalog.Service(serviceName);
            return queryResult.Response.Select(service => new Uri($"http://{service.ServiceAddress}:{service.ServicePort}/")).ToList();
        }
    }

    public class ConsulServiceLoadBalancer : IServiceLoadBalancer
    {
        private readonly ConcurrentDictionary<string, int> _indexDictionary = new ConcurrentDictionary<string, int>();

        public async Task<Uri> ChooseServer(List<Uri> servers)
        {
            var serviceName = servers.First().AbsolutePath.Split('/')[1];
            var index = _indexDictionary.AddOrUpdate(serviceName, 0, (_, i) => (i + 1) % servers.Count);
            return servers[index];
        }
    }

    public interface IServiceRegistry
    {
        Task<bool> RegisterService(ServiceRegistration registration);
    }

    public interface IServiceDiscovery
    {
        Task<List<Uri>> DiscoverServiceUri(string serviceName);
    }

    public interface IServiceLoadBalancer
    {
        Task<Uri> ChooseServer(List<Uri> servers);
    }

    public class ServiceRegistration
    {
        public string ID { get; set; }
        public string Name { get; set; }
        public string Address { get; set; }
        public int Port { get; set; }
        public string HealthCheckURL { get; set; }
        public int HealthCheckIntervalSeconds { get; set; } = 10;
        public int HealthCheckTimeoutSeconds { get; set; } = 5;
    }

    public class ConsulConfig
    {
        public string Address { get; set; }
        public string Datacenter { get; set; }
        public string Token { get; set; }
    }

    public class ConsulService
    {
        private readonly IServiceRegistry _serviceRegistry;
        private readonly IServiceDiscovery _serviceDiscovery;
        private readonly IServiceLoadBalancer _serviceLoadBalancer;

        public ConsulService(IServiceRegistry serviceRegistry, IServiceDiscovery serviceDiscovery, IServiceLoadBalancer serviceLoadBalancer)
        {
            _serviceRegistry = serviceRegistry;
            _serviceDiscovery = serviceDiscovery;
            _serviceLoadBalancer = serviceLoadBalancer;
        }

        public async Task RegisterService(ServiceRegistration registration)
        {
            await _serviceRegistry.RegisterService(registration);
        }

        public async Task<Uri> GetServiceUri(string serviceName)
        {
            var serviceUris = await _serviceDiscovery.DiscoverServiceUri(serviceName);
            var chosenServer = await _serviceLoadBalancer.ChooseServer(serviceUris);
            return chosenServer;
        }
    }

    class Program
    {
        static async Task Main(string[] args)
        {
            var consulConfig = new ConsulConfig
            {
                Address = "http://localhost:8500",
                Datacenter = "dc1",
                Token = ""
            };

            using var consul = new ConsulClient(config =>
            {
                config.Address = new Uri(consulConfig.Address);
            });

            var serviceRegistry = new ConsulServiceRegistry(Options.Create(consulConfig), consul);
            var serviceDiscovery = new ConsulServiceDiscovery(Options.Create(consulConfig), consul);
            var serviceLoadBalancer = new ConsulServiceLoadBalancer();

            var consulService = new ConsulService(serviceRegistry, serviceDiscovery, serviceLoadBalancer);

            var registration = new ServiceRegistration
            {
                Name = "serviceName",
                ID = "serviceId",
                Address = "localhost",
                Port = 5000,
                HealthCheckIntervalSeconds = 10,
                HealthCheckTimeoutSeconds = 5,
                HealthCheckURL = "http://localhost:5000/health"
            };
            await consulService.RegisterService(registration);

            var serviceUri = await consulService.GetServiceUri("serviceName");
            Console.WriteLine(serviceUri);
        }
    }
}

原創文章，作者：小藍，如若轉載，請註明出處：https://www.506064.com/zh-hant/n/305097.html