ServerFactory.cs

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using System;
using System.IO.Abstractions;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
 
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Server.Kestrel.Core;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
 
using Tgstation.Server.Host.Configuration;
using Tgstation.Server.Host.Core;
using Tgstation.Server.Host.Extensions;
using Tgstation.Server.Host.IO;
using Tgstation.Server.Host.Setup;
using Tgstation.Server.Host.System;
 
namespace Tgstation.Server.Host
{
    sealed class ServerFactory : IServerFactory
    {
        public const string AppSettings = "appsettings";
 
        public IIOManager IOManager { get; }
 
        readonly IAssemblyInformationProvider assemblyInformationProvider;
 
        readonly IFileSystem fileSystem;
 
        internal ServerFactory(
            IAssemblyInformationProvider assemblyInformationProvider,
            IIOManager ioManager,
            IFileSystem fileSystem)
        {
            this.assemblyInformationProvider = assemblyInformationProvider ?? throw new ArgumentNullException(nameof(assemblyInformationProvider));
            IOManager = ioManager ?? throw new ArgumentNullException(nameof(ioManager));
            this.fileSystem = fileSystem ?? throw new ArgumentNullException(nameof(fileSystem));
        }
 
        // TODO: Decomplexify
#pragma warning disable CA1506
        public async ValueTask<IServer?> CreateServer(string[] args, string? updatePath, CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(args);
 
            // need to shove this arg in to disable config reloading unless a user specifically overrides it
            if (!args.Any(arg => arg.Contains("hostBuilder:reloadConfigOnChange", StringComparison.OrdinalIgnoreCase))
                && String.IsNullOrWhiteSpace(Environment.GetEnvironmentVariable("hostBuilder__reloadConfigOnChange")))
            {
                var oldArgs = args;
                args = new string[oldArgs.Length + 1];
                Array.Copy(oldArgs, args, oldArgs.Length);
                args[oldArgs.Length] = "--hostBuilder:reloadConfigOnChange=false";
            }
 
            const string AppSettingsRelocationKey = $"--{AppSettings}-base-path=";
 
            var appsettingsRelativeBasePathArgument = args.FirstOrDefault(arg => arg.StartsWith(AppSettingsRelocationKey, StringComparison.Ordinal));
            string basePath;
            if (appsettingsRelativeBasePathArgument != null)
                basePath = IOManager.ResolvePath(appsettingsRelativeBasePathArgument[AppSettingsRelocationKey.Length..]);
            else
                basePath = IOManager.ResolvePath();
 
            // this is a massive bloody hack but I don't know a better way to do it
            // It's needed for the setup wizard
            Environment.SetEnvironmentVariable($"{InternalConfiguration.Section}__{nameof(InternalConfiguration.AppSettingsBasePath)}", basePath);
 
            IHostBuilder CreateDefaultBuilder() => Microsoft.Extensions.Hosting.Host.CreateDefaultBuilder(args)
                .ConfigureAppConfiguration((context, builder) =>
                {
                    builder.SetBasePath(basePath);
 
                    builder.AddYamlFile($"{AppSettings}.yml", optional: true, reloadOnChange: false)
                        .AddYamlFile($"{AppSettings}.{context.HostingEnvironment.EnvironmentName}.yml", optional: true, reloadOnChange: false);
 
                    // reorganize the builder so our yaml configs don't override the env/cmdline configs
                    // values obtained via debugger
                    var environmentJsonConfig = builder.Sources[2];
                    var envConfig = builder.Sources[3];
 
                    // CURSED
                    // https://github.com/dotnet/runtime/blob/30dc7e7aedb7aab085c7d9702afeae5bc5a43133/src/libraries/Microsoft.Extensions.Hosting/src/HostingHostBuilderExtensions.cs#L246-L249
#if !NET8_0
#error Validate this monstrosity works on current .NET
#endif
                    IConfigurationSource? cmdLineConfig;
                    IConfigurationSource baseYmlConfig, environmentYmlConfig;
                    if (args.Length == 0)
                    {
                        cmdLineConfig = null;
                        baseYmlConfig = builder.Sources[4];
                        environmentYmlConfig = builder.Sources[5];
                    }
                    else
                    {
                        cmdLineConfig = builder.Sources[4];
                        baseYmlConfig = builder.Sources[5];
                        environmentYmlConfig = builder.Sources[6];
                    }
 
                    builder.Sources[2] = baseYmlConfig;
                    builder.Sources[3] = environmentJsonConfig;
                    builder.Sources[4] = environmentYmlConfig;
                    builder.Sources[5] = envConfig;
 
                    if (cmdLineConfig != null)
                    {
                        builder.Sources[6] = cmdLineConfig;
                    }
                });
 
            var setupWizardHostBuilder = CreateDefaultBuilder()
                .UseSetupApplication(assemblyInformationProvider, IOManager);
 
            IPostSetupServices postSetupServices;
            using (var setupHost = setupWizardHostBuilder.Build())
            {
                ILogger<ServerFactory> logger = setupHost.Services.GetRequiredService<ILogger<ServerFactory>>();
                postSetupServices = setupHost.Services.GetRequiredService<IPostSetupServices>();
                await setupHost.RunAsync(cancellationToken);
 
                if (postSetupServices.GeneralConfiguration.SetupWizardMode == SetupWizardMode.Only)
                {
                    logger.LogInformation("Shutting down due to only running setup wizard.");
                    return null;
                }
 
                if (postSetupServices.ReloadRequired)
                {
                    logger.LogInformation("TGS must restart to reload the updated configuration.");
                    return null;
                }
            }
 
            var hostBuilder = CreateDefaultBuilder()
                .ConfigureWebHost(webHostBuilder =>
                    webHostBuilder
                        .UseKestrel(kestrelOptions =>
                        {
                            var serverPortProvider = kestrelOptions.ApplicationServices.GetRequiredService<IServerPortProvider>();
                            kestrelOptions.ListenAnyIP(
                                serverPortProvider.HttpApiPort,
                                listenOptions => listenOptions.Protocols = HttpProtocols.Http1); // Can't use Http1And2 without TLS. Let the reverse proxy handle it
 
                            // with 515 we lost the ability to test this effectively. Just bump it slightly above the default and let the existing limit hold us back
                            kestrelOptions.Limits.MaxRequestLineSize = 8400;
                        })
                        .UseIIS()
                        .UseIISIntegration()
                        .UseApplication(assemblyInformationProvider, IOManager, postSetupServices, fileSystem)
                        .SuppressStatusMessages(true)
                        .UseShutdownTimeout(
                            TimeSpan.FromMinutes(
                                postSetupServices.GeneralConfiguration.RestartTimeoutMinutes)));
 
            if (updatePath != null)
                hostBuilder.UseContentRoot(
                    IOManager.ResolvePath(
                        IOManager.GetDirectoryName(assemblyInformationProvider.Path)));
 
            return new Server(IOManager, hostBuilder, updatePath);
        }
#pragma warning restore CA1506
    }
}