作者：依乐祝
原文地址：https://www.cnblogs.com/yilezhu/p/9852711.html
上篇文章给大家分享了如何集成我写的一个Ocelot扩展插件把Ocelot的配置存储到数据库中。并没有对实现原理进行相应的阐述。今天抽空把实现的原理给大家说道说道。明白原理后，大家就可以自行改写进行扩展来满足自身需要了！
再次感觉张队的审稿，并给出的修改意见！
源码解析过程
大家可以自行分析Ocelot的源码，我通过分析ocelot的源码得出，如果要实现重写配置文件的方式，只需要写一个类来实现IFileConfigurationRepository这个接口即可。
代码如下：
/// <summary>
/// yilezhu
/// 2018.10.22
/// 实现从SQLSERVER数据库中提取配置信息
/// </summary>
public class SqlServerFileConfigurationRepository : IFileConfigurationRepository
{
private readonly IOcelotCache<FileConfiguration> _cache;
private readonly IOcelotLogger _logger;
private readonly ConfigAuthLimitCacheOptions _option;
public SqlServerFileConfigurationRepository(ConfigAuthLimitCacheOptions option, IOcelotCache<FileConfiguration> cache, IOcelotLoggerFactory loggerFactory)
{
_option = option;
_cache = cache;
_logger = loggerFactory.CreateLogger<SqlServerFileConfigurationRepository>();
}
public Task<Response> Set(FileConfiguration fileConfiguration)
{
_cache.AddAndDelete(_option.CachePrefix + "FileConfiguration", fileConfiguration, TimeSpan.FromSeconds(1800), "");
return Task.FromResult((Response)new OkResponse());
}
/// <summary>
/// 提取配置信息
/// </summary>
/// <returns></returns>
public async Task<Response<FileConfiguration>> Get()
{
var config = _cache.Get(_option.CachePrefix + "FileConfiguration", "");
if (config != null)
{
return new OkResponse<FileConfiguration>(config);
}
#region 提取配置信息
var file = new FileConfiguration();
string glbsql = "select top 1 * from OcelotGlobalConfiguration where IsDefault=1";
//提取全局配置信息
using (var connection = new SqlConnection(_option.DbConnectionStrings))
{
var result = await connection.QueryFirstOrDefaultAsync<OcelotGlobalConfiguration>(glbsql);
if (result != null)
{
var glb = new FileGlobalConfiguration();
glb.BaseUrl = result.BaseUrl;
glb.DownstreamScheme = result.DownstreamScheme;
glb.RequestIdKey = result.RequestIdKey;
if (!String.IsNullOrEmpty(result.HttpHandlerOptions))
{
glb.HttpHandlerOptions = result.HttpHandlerOptions.ToObject<FileHttpHandlerOptions>();
}
if (!String.IsNullOrEmpty(result.LoadBalancerOptions))
{
glb.LoadBalancerOptions = result.LoadBalancerOptions.ToObject<FileLoadBalancerOptions>();
}
if (!String.IsNullOrEmpty(result.QoSOptions))
{
glb.QoSOptions = result.QoSOptions.ToObject<FileQoSOptions>();
}
if (!String.IsNullOrEmpty(result.ServiceDiscoveryProvider))
{
glb.ServiceDiscoveryProvider = result.ServiceDiscoveryProvider.ToObject<FileServiceDiscoveryProvider>();
}
file.GlobalConfiguration = glb;
//提取路由信息
string routesql = "select * from OcelotReRoutes where OcelotGlobalConfigurationId=@OcelotGlobalConfigurationId and IsStatus=1";
var routeresult = (await connection.QueryAsync<OcelotReRoutes>(routesql, new { OcelotGlobalConfigurationId=result.Id })).AsList();
if (routeresult != null && routeresult.Count > 0)
{
var reroutelist = new List<FileReRoute>();
foreach (var model in routeresult)
{
var m = new FileReRoute();
if (!String.IsNullOrEmpty(model.AuthenticationOptions))
{
m.AuthenticationOptions = model.AuthenticationOptions.ToObject<FileAuthenticationOptions>();
}
if (!String.IsNullOrEmpty(model.CacheOptions))
{
m.FileCacheOptions = model.CacheOptions.ToObject<FileCacheOptions>();
}
if (!String.IsNullOrEmpty(model.DelegatingHandlers))
{
m.DelegatingHandlers = model.DelegatingHandlers.ToObject<List<string>>();
}
if (!String.IsNullOrEmpty(model.LoadBalancerOptions))
{
m.LoadBalancerOptions = model.LoadBalancerOptions.ToObject<FileLoadBalancerOptions>();
}
if (!String.IsNullOrEmpty(model.QoSOptions))
{
m.QoSOptions = model.QoSOptions.ToObject<FileQoSOptions>();
}
if (!String.IsNullOrEmpty(model.DownstreamHostAndPorts))
{
m.DownstreamHostAndPorts = model.DownstreamHostAndPorts.ToObject<List<FileHostAndPort>>();
}
//开始赋值
m.DownstreamPathTemplate = model.DownstreamPathTemplate;
m.DownstreamScheme = model.DownstreamScheme;
m.Key = model.Key;
m.Priority = model.Priority ?? 0;
m.RequestIdKey = model.RequestIdKey;
m.ServiceName = model.ServiceName;
m.Timeout = model.Timeout ?? 0;
m.UpstreamHost = model.UpstreamHost;
if (!String.IsNullOrEmpty(model.UpstreamHttpMethod))
{
m.UpstreamHttpMethod = model.UpstreamHttpMethod.ToObject<List<string>>();
}
m.UpstreamPathTemplate = model.UpstreamPathTemplate;
reroutelist.Add(m);
}
file.ReRoutes = reroutelist;
}
}
else
{
throw new Exception("未监测到配置信息");
}
}
#endregion
if (file.ReRoutes == null || file.ReRoutes.Count == 0)
{
return new OkResponse<FileConfiguration>(null);
}
return new OkResponse<FileConfiguration>(file);
}
}当然，既然我们已经重新实现了这个接口，那么就得进行相应的DI了。这里我们扩展下IOcelotBuilder方法，代码如下,主要就是进行相应的服务的DI：
/// <summary>
/// yilezhu
/// 2018.10.22
/// 基于Ocelot扩展的依赖注入
/// </summary>
public static class ServiceCollectionExtensions
{
/// <summary>
/// 添加默认的注入方式，所有需要传入的参数都是用默认值
/// </summary>
/// <param name="builder"></param>
/// <returns></returns>
public static IOcelotBuilder AddAuthLimitCache(this IOcelotBuilder builder, Action<ConfigAuthLimitCacheOptions> option)
{
builder.Services.Configure(option);
builder.Services.AddSingleton(
resolver => resolver.GetRequiredService<IOptions<ConfigAuthLimitCacheOptions>>().Value);
#region 注入其他配置信息
//重写提取Ocelot配置信息，
builder.Services.AddSingleton(DataBaseConfigurationProvider.Get);
//builder.Services.AddHostedService<FileConfigurationPoller>();
builder.Services.AddSingleton<IFileConfigurationRepository, SqlServerFileConfigurationRepository>();
//注入自定义限流配置
//注入认证信息
#endregion
return builder;
}
}接下来就是重写，OcelotBuild里面配置文件的获取方式了。这里我选择的是对IApplicationBuilder进行扩展，因为这样方便做一些其他的事情，比如，重写限流，集成自定义的验证等等。具体代码如下：
/// <summary>
/// yilezhu
/// 2018.10.22
/// 扩展IApplicationBuilder，新增use方法
/// </summary>
public static class OcelotMiddlewareExtensions
{
/// <summary>
/// 扩展UseOcelot
/// </summary>
/// <param name="builder"></param>
/// <returns></returns>
public static async Task<IApplicationBuilder> UseAhphOcelot(this IApplicationBuilder builder)
{
await builder.UseAhphOcelot(new OcelotPipelineConfiguration());
return builder;
}
/// <summary>
/// 重写Ocelot,带参数
/// </summary>
/// <param name="builder"></param>
/// <param name="pipelineConfiguration"></param>
/// <returns></returns>
public static async Task<IApplicationBuilder> UseAhphOcelot(this IApplicationBuilder builder, OcelotPipelineConfiguration pipelineConfiguration)
{
var configuration = await CreateConfiguration(builder);
ConfigureDiagnosticListener(builder);
return CreateOcelotPipeline(builder, pipelineConfiguration);
}
private static async Task<IInternalConfiguration> CreateConfiguration(IApplicationBuilder builder)
{
// make configuration from file system?
// earlier user needed to add ocelot files in startup configuration stuff, asp.net will map it to this
//var fileConfig = builder.ApplicationServices.GetService<IOptionsMonitor<FileConfiguration>>();
var fileConfig = await builder.ApplicationServices.GetService<IFileConfigurationRepository>().Get();
// now create the config
var internalConfigCreator = builder.ApplicationServices.GetService<IInternalConfigurationCreator>();
var internalConfig = await internalConfigCreator.Create(fileConfig.Data);
//Configuration error, throw error message
if (internalConfig.IsError)
{
ThrowToStopOcelotStarting(internalConfig);
}
// now save it in memory
var internalConfigRepo = builder.ApplicationServices.GetService<IInternalConfigurationRepository>();
internalConfigRepo.AddOrReplace(internalConfig.Data);
//fileConfig.OnChange(async (config) =>
//{
// var newInternalConfig = await internalConfigCreator.Create(config);
// internalConfigRepo.AddOrReplace(newInternalConfig.Data);
//});
var adminPath = builder.ApplicationServices.GetService<IAdministrationPath>();
var configurations = builder.ApplicationServices.GetServices<OcelotMiddlewareConfigurationDelegate>();
// Todo - this has just been added for consul so far...will there be an ordering problem in the future? Should refactor all config into this pattern?
foreach (var configuration in configurations)
{
await configuration(builder);
}
if (AdministrationApiInUse(adminPath))
{
//We have to make sure the file config is set for the ocelot.env.json and ocelot.json so that if we pull it from the
//admin api it works...boy this is getting a spit spags boll.
var fileConfigSetter = builder.ApplicationServices.GetService<IFileConfigurationSetter>();
// await SetFileConfig(fileConfigSetter, fileConfig.Data);
}
return GetOcelotConfigAndReturn(internalConfigRepo);
}
private static bool AdministrationApiInUse(IAdministrationPath adminPath)
{
return adminPath != null;
}
//private static async Task SetFileConfig(IFileConfigurationSetter fileConfigSetter, IOptionsMonitor<FileConfiguration> fileConfig)
//{
// var response = await fileConfigSetter.Set(fileConfig.CurrentValue);
// if (IsError(response))
// {
// ThrowToStopOcelotStarting(response);
// }
//}
private static bool IsError(Response response)
{
return response == null || response.IsError;
}
private static IInternalConfiguration GetOcelotConfigAndReturn(IInternalConfigurationRepository provider)
{
var ocelotConfiguration = provider.Get();
if (ocelotConfiguration?.Data == null || ocelotConfiguration.IsError)
{
ThrowToStopOcelotStarting(ocelotConfiguration);
}
return ocelotConfiguration.Data;
}
private static void ThrowToStopOcelotStarting(Response config)
{
throw new Exception($"Unable to start Ocelot, errors are: {string.Join(",", config.Errors.Select(x => x.ToString()))}");
}
private static IApplicationBuilder CreateOcelotPipeline(IApplicationBuilder builder, OcelotPipelineConfiguration pipelineConfiguration)
{
var pipelineBuilder = new OcelotPipelineBuilder(builder.ApplicationServices);
//重写自定义管道
pipelineBuilder.BuildAhphOcelotPipeline(pipelineConfiguration);
var firstDelegate = pipelineBuilder.Build();
/*
inject first delegate into first piece of asp.net middleware..maybe not like this
then because we are updating the http context in ocelot it comes out correct for
rest of asp.net..
*/
builder.Properties["analysis.NextMiddlewareName"] = "TransitionToOcelotMiddleware";
builder.Use(async (context, task) =>
{
var downstreamContext = new DownstreamContext(context);
await firstDelegate.Invoke(downstreamContext);
});
return builder;
}
private static void ConfigureDiagnosticListener(IApplicationBuilder builder)
{
var env = builder.ApplicationServices.GetService<IHostingEnvironment>();
var listener = builder.ApplicationServices.GetService<OcelotDiagnosticListener>();
var diagnosticListener = builder.ApplicationServices.GetService<DiagnosticListener>();
diagnosticListener.SubscribeWithAdapter(listener);
}
}这其中最主要的代码就是，重写配置文件获取这块。我在下面进行了截图，并圈出来了，大家自行查看吧。
代码重写好了。由于我们服务注册时通过扩展IOcelotBuilder，所以，我们需要在ConfigureServices方法引入Ocelot服务的时候比Ocelot多写一个方法，并传入相关的配置信息，如下所示：
services.AddOcelot()//注入Ocelot服务
.AddAuthLimitCache(option=> {
option.DbConnectionStrings = "Server=.;Database=Ocelot;User ID=sa;Password=1;";
});这里的目的就是为了注入我们实现了IFileConfigurationRepository接口的SqlServerFileConfigurationRepository这个类。
接下来就是在管道中使用我们重写的Ocelot服务了。如下所示，在Configure方法中按如下代码进行使用：
app.UseAhphOcelot().Wait();好了，以上就是实现的整个过程了。经过这么一分析是不是觉得很简单呢。当然具体为什么按照上面处理就能够从数据库获取配置了呢，这个还需要你分析了源码后才能了解。我也只是给你引路，传达我实现的思路。
源码
https://github.com/yilezhu/Ocelot.ConfigAuthLimitCache
总结
今天抽空对上篇文章进行了补充说明，目的是给大家阐述下，配置文件存储到数据库中的实现过程及原理。让你能够根据自身需要来进行改写来满足你的业务需求。当然我也只是给你引路，具体为什么这样实现下就能够成功呢？答案在Ocelot的源码中。
如果你想了解更多Ocelot的定制相关的·内容可以看我一个朋友写的系列博客，博客地址：https://www.cnblogs.com/jackcao/p/9928879.html 【.NET Core微服务实战-统一身份认证】网关篇，这里给你详细介绍了如何进行自定义限流以及客户端授权并重写Ocelot缓存成Redis！有兴趣的可以看下！
作者：依乐祝
出处：https://www.cnblogs.com/yilezhu
联系：1015657114@qq.com .NET Core实战项目交流群：637326624
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。如有问题或建议，请多多赐教，非常感谢。
