feat(deployment): add secure Linux runtime (#17)

src/FinalFactory.Rendezvous.Server/Program.cs

@@ -3,6 +3,7 @@ using FinalFactory.Rendezvous.Contracts;
 using FinalFactory.Rendezvous.Server.Abuse;
 using FinalFactory.Rendezvous.Server.Browser;
 using FinalFactory.Rendezvous.Server.ConnectionOutcomes;
+using FinalFactory.Rendezvous.Server.Deployment;
 using FinalFactory.Rendezvous.Server.Http;
 using FinalFactory.Rendezvous.Server.JoinAttempts;
 using FinalFactory.Rendezvous.Server.Observability;
@@ -235,8 +236,29 @@ AbuseProtectionOptions configuredAbuseProtection = builder.Configuration
 builder.Services.Configure<ForwardedHeadersOptions>(options =>
     TrustedProxyForwarding.Configure(options, configuredAbuseProtection));
 
+DeploymentOptions deploymentOptions = builder.Configuration
+    .GetSection(DeploymentOptions.SectionName)
+    .Get<DeploymentOptions>() ?? new DeploymentOptions();
+if (!builder.Environment.IsDevelopment() && !isOpenApiGeneration)
+{
+    IReadOnlyList<string> deploymentErrors = deploymentOptions.ValidateProduction(
+        configuredAbuseProtection,
+        builder.Configuration["AllowedHosts"]);
+    if (deploymentErrors.Count > 0)
+    {
+        throw new DeploymentConfigurationException(deploymentErrors);
+    }
+}
+
+builder.Services.AddSingleton(Microsoft.Extensions.Options.Options.Create(deploymentOptions));
+builder.Services.Configure<HostOptions>(options =>
+    options.ShutdownTimeout = TimeSpan.FromSeconds(deploymentOptions.DrainDeadlineSeconds + 10));
+
 SystemRendezvousClock rendezvousClock = new();
-EphemeralStoreOptions stateOptions = new();
+EphemeralStoreOptions stateOptions = new()
+{
+    GracefulDrainLifetime = TimeSpan.FromSeconds(deploymentOptions.DrainDeadlineSeconds),
+};
 InMemoryEphemeralRendezvousStore stateStore = new(
     stateOptions,
     rendezvousClock,
@@ -304,10 +326,12 @@ if (!isOpenApiGeneration)
     builder.Services.AddSingleton<NatMediationProcessor>();
     builder.Services.AddHostedService(static services =>
         services.GetRequiredService<UdpMediatorService>());
+    // Hosted services stop in reverse registration order. Drain must complete while
+    // Kestrel and the UDP mediator are still able to finish bounded in-flight work.
+    builder.Services.AddHostedService<GracefulDrainService>();
 }
 
 WebApplication app = builder.Build();
-app.Lifetime.ApplicationStopping.Register(() => stateStore.BeginDrain());
 
 if (TrustedProxyForwarding.IsEnabled(configuredAbuseProtection))
 {