feat(observability): add diagnostic dashboards (#27)

src/FinalFactory.Rendezvous.Server/Program.cs

@@ -4,6 +4,7 @@ using FinalFactory.Rendezvous.Server.Abuse;
 using FinalFactory.Rendezvous.Server.Browser;
 using FinalFactory.Rendezvous.Server.ConnectionOutcomes;
 using FinalFactory.Rendezvous.Server.Deployment;
+using FinalFactory.Rendezvous.Server.Diagnostics;
 using FinalFactory.Rendezvous.Server.Http;
 using FinalFactory.Rendezvous.Server.JoinAttempts;
 using FinalFactory.Rendezvous.Server.Observability;
@@ -251,6 +252,37 @@ if (!builder.Environment.IsDevelopment() && !isOpenApiGeneration)
 }
 
 builder.Services.AddSingleton(Microsoft.Extensions.Options.Options.Create(deploymentOptions));
+DiagnosticDashboardOptions diagnosticDashboardOptions = builder.Configuration
+    .GetSection(DiagnosticDashboardOptions.SectionName)
+    .Get<DiagnosticDashboardOptions>() ?? new DiagnosticDashboardOptions();
+IReadOnlyList<string> diagnosticErrors = diagnosticDashboardOptions.Validate();
+if (diagnosticErrors.Count > 0)
+{
+    throw new DeploymentConfigurationException(diagnosticErrors);
+}
+builder.Services.AddSingleton(
+    Microsoft.Extensions.Options.Options.Create(diagnosticDashboardOptions));
+PrometheusMetricsOptions metricsOptions = builder.Configuration
+    .GetSection(PrometheusMetricsOptions.SectionName)
+    .Get<PrometheusMetricsOptions>() ?? new PrometheusMetricsOptions();
+IReadOnlyList<string> metricsErrors = metricsOptions.Validate();
+if (metricsErrors.Count > 0)
+{
+    throw new DeploymentConfigurationException(metricsErrors);
+}
+builder.Services.AddSingleton(Microsoft.Extensions.Options.Options.Create(metricsOptions));
+MetricsAccessCredential? metricsCredential = null;
+if (metricsOptions.Enabled && !isOpenApiGeneration)
+{
+    EnvironmentSecretProvider metricsSecrets = new();
+    if (!MetricsAccessCredential.TryCreate(metricsOptions, metricsSecrets, out metricsCredential)
+        || metricsCredential is null)
+    {
+        throw new DeploymentConfigurationException(
+            [$"{PrometheusMetricsOptions.SectionName}:BearerTokenSecretReference did not resolve to 32-128 visible ASCII bytes."]);
+    }
+    builder.Services.AddSingleton(metricsCredential);
+}
 builder.Services.Configure<HostOptions>(options =>
     options.ShutdownTimeout = TimeSpan.FromSeconds(deploymentOptions.DrainDeadlineSeconds + 10));
 
@@ -349,6 +381,8 @@ app.MapOpenApi();
 app.MapRendezvousContractEndpoints();
 app.MapOperatorEndpoints();
 app.MapRendezvousHealthEndpoints();
+app.MapDiagnosticDashboardEndpoints();
+app.MapPrometheusMetricsEndpoint(metricsOptions, metricsCredential);
 
 await app.RunAsync();