題外話
筆者有個習慣，就是在接觸新的東西時，一定要先搞清楚新事物的基本概念和背景，對之有個相對全面的了解之后再開始進入實際的編碼，這樣做最主要的原因是盡量避免由于對新事物的認知誤區導致更大的缺陷，Bug 一旦發生，將比普通的代碼缺陷帶來更加昂貴的修復成本，
相信有了前一篇和園子里其他同學的文章，你已經基本上掌握了使用 Consul 所需要具備的背景知識，那么就讓我們來看下，具體到 ASP.NET Core 中，如何更加優雅的編碼，
Consul 在 ASP.NET CORE 中的使用
Consul服務在注冊時需要注意幾個問題：
- 那就是必須是在服務完全啟動之后再進行注冊，否則可能導致服務在啟動程序中已經注冊到 Consul Server，這時候我們要利用 IApplicationLifetime 應用程式生命周期管理中的 ApplicationStarted 事件，
- 應用程式向 Consul 注冊時，應該在本地記錄應用 ID，以此解決每次重啟之后，都會向 Consul 注冊一個新實體的問題，便于管理，
具體代碼如下：
注意：以下均為根據排版要求所展示的示意代碼，并非完整的代碼
1. 服務治理之服務注冊
- 1.1 服務注冊擴展方法
public static IApplicationBuilder AgentServiceRegister(this IApplicationBuilder app,
IApplicationLifetime lifetime,
IConfiguration configuration,
IConsulClient consulClient,
ILogger logger)
{
try
{
var urlsConfig = configuration["server.urls"];
ArgumentCheck.NotNullOrWhiteSpace(urlsConfig, "未找到組態檔中關于 server.urls 相關配置！");
var urls = urlsConfig.Split(';');
var port = urls.First().Substring(httpUrl.LastIndexOf(":") + 1);
var ip = GetPrimaryIPAddress(logger);
var registrationId = GetRegistrationId(logger);
var serviceName = configuration["Apollo:AppId"];
ArgumentCheck.NotNullOrWhiteSpace(serviceName, "未找到組態檔中 Apollo:AppId 對應的配置項！");
//程式啟動之后注冊
lifetime.ApplicationStarted.Register(() =>
{
var healthCheck = new AgentServiceCheck
{
DeregisterCriticalServiceAfter = TimeSpan.FromSeconds(5),
Interval = 5,
HTTP = $"http://{ip}:{port}/health",
Timeout = TimeSpan.FromSeconds(5),
TLSSkipVerify = true
};
var registration = new AgentServiceRegistration
{
Checks = new[] { healthCheck },
ID = registrationId,
Name = serviceName.ToLower(),
Address = ip,
Port = int.Parse(port),
Tags = ""//手動高亮
};
consulClient.Agent.ServiceRegister(registration).Wait();
logger.LogInformation($"服務注冊成功! 注冊地址：{((ConsulClient)consulClient).Config.Address}, 注冊資訊：{registration.ToJson()}");
});
//優雅的退出
lifetime.ApplicationStopping.Register(() =>
{
consulClient.Agent.ServiceDeregister(registrationId).Wait();
});
return app;
}
catch (Exception ex)
{
logger?.LogSpider(LogLevel.Error, "服務發現注冊失敗！", ex);
throw ex;
}
}
private static string GetPrimaryIPAddress(ILogger logger)
{
string output = GetLocalIPAddress();
logger?.LogInformation(LogLevel.Information, "獲取本地網卡地址結果：{0}", output);
if (output.Length > 0)
{
var ips = output.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
if (ips.Length == 1) return ips[0];
else
{
var localIPs = ips.Where(w => w.StartsWith("10"));//內網網段
if (localIPs.Count() > 0) return localIPs.First();
else return ips[0];
}
}
else
{
logger?.LogSpider(LogLevel.Error, "沒有獲取到有效的IP地址，無法注冊服務到服務中心！");
throw new Exception("獲取本機IP地址出錯，無法注冊服務到注冊中心！");
}
}
public static string GetLocalIPAddress()
{
if (!string.IsNullOrWhiteSpace(_localIPAddress)) return _localIPAddress;
string output = "";
try
{
foreach (NetworkInterface item in NetworkInterface.GetAllNetworkInterfaces())
{
if (item.OperationalStatus != OperationalStatus.Up) continue;
var adapterProperties = item.GetIPProperties();
if (adapterProperties.GatewayAddresses.Count == 0) continue;
foreach (UnicastIPAddressInformation address in adapterProperties.UnicastAddresses)
{
if (address.Address.AddressFamily != AddressFamily.InterNetwork) continue;
if (IPAddress.IsLoopback(address.Address)) continue;
output = output += address.Address.ToString() + ",";
}
}
}
catch (Exception e)
{
Console.WriteLine("獲取本機IP地址失敗！");
throw e;
}
if (output.Length > 0)
_localIPAddress = output.TrimEnd(',');
else
_localIPAddress = "Unknown";
return _localIPAddress;
}
private static string GetRegistrationId(ILogger logger)
{
try
{
var basePath = Directory.GetCurrentDirectory();
var folderPath = Path.Combine(basePath, "registrationid");
if (!Directory.Exists(folderPath))
Directory.CreateDirectory(folderPath);
var path = Path.Combine(basePath, "registrationid", ".id");
if (File.Exists(path))
{
var lines = File.ReadAllLines(path, Encoding.UTF8);
if (lines.Count() > 0 && !string.IsNullOrEmpty(lines[0]))
return lines[0];
}
var id = Guid.NewGuid().ToString();
File.AppendAllLines(path, new[] { id });
return id;
}
catch (Exception e)
{
logger?.LogWarning(e, "獲取 Registration Id 錯誤");
return Guid.NewGuid().ToString();
}
}
- 1.2 健康檢查中間件
既然健康檢查是通過http請求來實作的，那么我們可以通過 HealthMiddleware 中間件來實作：
public static void UseHealth(this IApplicationBuilder app)
{
app.UseMiddleware<HealthMiddleware>();
}
public class HealthMiddleware
{
private readonly RequestDelegate _next;
private readonly string _healthPath = "/health";
public HealthMiddleware(RequestDelegate next, IConfiguration configuration)
{
this._next = next;
var healthPath = configuration["Consul:HealthPath"];
if (!string.IsNullOrEmpty(healthPath))
{
this._healthPath = healthPath;
}
}
//監控檢查可以回傳更多的資訊，例如服務器資源資訊
public async Task Invoke(HttpContext httpContext)
{
if (httpContext.Request.Path == this._healthPath)
{
httpContext.Response.StatusCode = (int)HttpStatusCode.OK;
await httpContext.Response.WriteAsync("I'm OK!");
}
else
await this._next(httpContext);
}
}
- 1.3 Startup 配置
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
//手動高亮
services.AddSingleton<IConsulClient>(sp =>
{
ArgumentCheck.NotNullOrWhiteSpace(this.Configuration["Consul:Address"], "未找到配置中Consul:Address對應的配置");
return new ConsulClient(c => { c.Address = new Uri(this.Configuration["Consul:Address"]); });
});
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env, IApplicationLifetime lifetime, IConsulClient consulClient, ILogger<Startup> logger)
{
...
app.UseHealth();//手動高亮
app.UseMvc();
app.AgentServiceRegister(lifetime, this.Configuration, consulClient, logger);//手動高亮
}
2. 服務治理之服務發現
public class ServiceManager : IServiceManager
{
private readonly IHttpClientFactory _httpClientFactory;
private readonly ILogger _logger;
private readonly IConsulClient _consulClient;
private readonly IList<Func<StrategyDelegate, StrategyDelegate>> _components;
private StrategyDelegate _strategy;
public ServiceManager(IHttpClientFactory httpClientFactory,
IConsulClient consulClient,
ILogger<ServiceManager> logger)
{
this._cancellationTokenSource = new CancellationTokenSource();
this._components = new List<Func<StrategyDelegate, StrategyDelegate>>();
this._httpClientFactory = httpClientFactory;
this._optionsConsulConfig = optionsConsulConfig;
this._logger = logger;
this._consulClient = consulClient;
}
public async Task<HttpClient> GetHttpClientAsync(string serviceName, string errorIPAddress = null, string hashkey = null)
{
//重要：獲取所有健康的服務
var resonse = (await this._consulClient.Health.Service(serviceName.ToLower(), this._cancellationTokenSource.Token)).Response;
var filteredService = this.GetServiceNode(serviceName, resonse.ToArray(), hashkey);
return this.CreateHttpClient(serviceName.ToLower(), filteredService.Service.Address, filteredService.Service.Port);
}
private ServiceEntry GetServiceNode(string serviceName, ServiceEntry[] services, string hashKey = null)
{
if (this._strategy == null)
{
lock (this) { if (this._strategy == null) this._strategy = this.Build(); }
}
//策略過濾
var filterService = this._strategy(serviceName, services, hashKey);
return filterService.FirstOrDefault();
}
private HttpClient CreateHttpClient(string serviceName, string address, int port)
{
var httpClient = this._httpClientFactory.CreateClient(serviceName);
httpClient.BaseAddress = new System.Uri($"http://{address}:{port}");
return httpClient;
}
}
服務治理之——訪問策略
服務在注冊時，可以通過配置或其他手段給當前服務配置相應的 Tags ，同樣在服務獲取時，我們也將同時獲取到該服務的 Tags, 這對于我們實作策略訪問夯實了基礎，例如開發和測驗共用一套服務注冊發現基礎設施（當然這實際不可能），我們就可以通過給每個服務設定環境 Tag ，以此來實作環境隔離的訪問，這個 tag 維度是沒有限制的，開發人員完全可以根據自己的實際需求進行打標簽，這樣既可以通過內置默認策略兜底，也允許開發人員在此基礎之上動態的定制訪問策略，
筆者所實作的訪問策略方式類似于 Asp.Net Core Middleware 的方式，并且筆者認為這個設計非常值得借鑒，并參考了部分原始碼實作,使用方式也基本相同，
原始碼實作如下：
//策略委托
public delegate ServiceEntry[] StrategyDelegate(string serviceName, ServiceEntry[] services, string hashKey = null);
//服務管理
public class ServiceManager:IServiceManager
{
private readonly IList<Func<StrategyDelegate, StrategyDelegate>> _components;
private StrategyDelegate _strategy;//策略鏈
public ServiceManager()
{
this._components = new List<Func<StrategyDelegate, StrategyDelegate>>();
}
//增加自定義策略
public IServiceManager UseStrategy(Func<StrategyDelegate, StrategyDelegate> strategy)
{
_components.Add(strategy);
return this;
}
//build 最終策略鏈
private StrategyDelegate Build()
{
StrategyDelegate strategy = (sn, services, key) =>
{
return new DefaultStrategy().Invoke(null, sn, services, key);
};
foreach (var component in _components.Reverse())
{
strategy = component(strategy);
}
return strategy;
}
}
public class DefaultStrategy : IStrategy
{
private ushort _idx;
public DefaultStrategy(){}
public ServiceEntry[] Invoke(StrategyDelegate next, string serviceName, ServiceEntry[] services, string hashKey = null)
{
var service = services.Length == 1 ? services[0] : services[this._idx++ % services.Length];
var result = new[] { service };
return next != null ? next(serviceName, result, hashKey) : result;
}
}
自定義策略擴展方法以及使用
public static IApplicationBuilder UseStrategy(this IApplicationBuilder app)
{
var serviceManager = app.ApplicationServices.GetRequiredService<IServiceManager>();
var strategies = app.ApplicationServices.GetServices<IStrategy>();
//注冊所有的策略
foreach (var strategy in strategies)
{
serviceManager.UseStrategy(next =>
{
return (serviceName, services, hashKey) => strategy.Invoke(next, serviceName, services, hashKey);
});
}
return app;
}
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
...
services.AddSingleton<IStrategy, CustomStrategy>(); //自定義策略1
services.AddSingleton<IStrategy, CustomStrategy2>(); //自定義測率2
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env, IApplicationLifetime lifetime, IConsulClient consulClient, ILogger<Startup> logger)
{
app.UseStrategy(); //手動高亮
app.AgentServiceRegister(lifetime, this.Configuration, consulClient, logger);
}
}
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標籤：.NET Core
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