fengling-gateway/Program.cs

using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;
using Serilog;
using Yarp.ReverseProxy.Configuration;
using Yarp.ReverseProxy.LoadBalancing;
using YarpGateway.Config;
using YarpGateway.Data;
using YarpGateway.DynamicProxy;
using YarpGateway.LoadBalancing;
using YarpGateway.Middleware;
using YarpGateway.Services;
using StackExchange.Redis;

var builder = WebApplication.CreateBuilder(args);

builder.Host.UseSerilog(
    (context, services, configuration) =>
        configuration
            .ReadFrom.Configuration(context.Configuration)
            .ReadFrom.Services(services)
            .Enrich.FromLogContext()
);

builder.Services.Configure<JwtConfig>(builder.Configuration.GetSection("Jwt"));
builder.Services.Configure<RedisConfig>(builder.Configuration.GetSection("Redis"));
builder.Services.AddSingleton(sp => sp.GetRequiredService<IOptions<RedisConfig>>().Value);

builder.Services.AddDbContextFactory<GatewayDbContext>(options =>
    options.UseNpgsql(builder.Configuration.GetConnectionString("DefaultConnection"))
);

builder.Services.AddSingleton<DatabaseRouteConfigProvider>();
builder.Services.AddSingleton<DatabaseClusterConfigProvider>();
builder.Services.AddSingleton<IRouteCache, RouteCache>();

builder.Services.AddSingleton<IRedisConnectionManager, RedisConnectionManager>();
builder.Services.AddSingleton<IConnectionMultiplexer>(sp =>
{
    var config = sp.GetRequiredService<RedisConfig>();
    var connectionOptions = ConfigurationOptions.Parse(config.ConnectionString);
    connectionOptions.AbortOnConnectFail = false;
    connectionOptions.ConnectRetry = 3;
    connectionOptions.ConnectTimeout = 5000;
    connectionOptions.SyncTimeout = 3000;
    connectionOptions.DefaultDatabase = config.Database;

    var connection = ConnectionMultiplexer.Connect(connectionOptions);
    connection.ConnectionFailed += (sender, e) =>
    {
        Serilog.Log.Error(e.Exception, "Redis connection failed");
    };
    connection.ConnectionRestored += (sender, e) =>
    {
        Serilog.Log.Information("Redis connection restored");
    };

    return connection;
});

builder.Services.AddSingleton<ILoadBalancingPolicy, DistributedWeightedRoundRobinPolicy>();

builder.Services.AddSingleton<DynamicProxyConfigProvider>();
builder.Services.AddSingleton<IProxyConfigProvider>(sp => sp.GetRequiredService<DynamicProxyConfigProvider>());

builder.Services.AddHostedService<PgSqlConfigChangeListener>();

var corsSettings = builder.Configuration.GetSection("Cors");
builder.Services.AddCors(options =>
{
    var allowAnyOrigin = corsSettings.GetValue<bool>("AllowAnyOrigin");
    var allowedOrigins = corsSettings.GetSection("AllowedOrigins").Get<string[]>() ?? Array.Empty<string>();

    options.AddPolicy("AllowFrontend", policy =>
    {
        if (allowAnyOrigin)
        {
            policy.AllowAnyOrigin();
        }
        else
        {
            policy.WithOrigins(allowedOrigins);
        }

        policy.AllowAnyHeader()
              .AllowAnyMethod()
              .AllowCredentials();
    });
});

builder.Services.AddControllers();
builder.Services.AddHttpForwarder();
builder.Services.AddRouting();
builder.Services.AddReverseProxy();

var app = builder.Build();

app.UseCors("AllowFrontend");
app.UseMiddleware<JwtTransformMiddleware>();
app.UseMiddleware<TenantRoutingMiddleware>();

app.MapControllers();
app.MapReverseProxy();

await app.Services.GetRequiredService<IRouteCache>().InitializeAsync();

try
{
    Log.Information("Starting YARP Gateway");
    app.Run();
}
catch (Exception ex)
{
    Log.Fatal(ex, "Application terminated unexpectedly");
}
finally
{
    Log.CloseAndFlush();
}