feat: migrate push to SSE with WebSocket rollout compatibility

k8s/exceptionless/templates/api.yaml

@@ -28,6 +28,11 @@ spec:
       annotations:
         checksum/config: {{ include (print $.Template.BasePath "/config.yaml") . | sha256sum }}
     spec:
+      # SSE connections are long-lived; give the pod enough time to drain before SIGTERM.
+      # The preStop sleep lets the ALB/ingress controller deregister the pod before traffic stops,
+      # then the remaining window allows ASP.NET Core to cancel RequestAborted tokens and clean up.
+      # When push is eventually enabled behind a Gateway API RoutePolicy, revisit this value.
+      terminationGracePeriodSeconds: 60
       topologySpreadConstraints:
         - maxSkew: 1
           topologyKey: kubernetes.io/hostname
@@ -39,6 +44,13 @@ spec:
         - name: {{ template "exceptionless.name" . }}-api
           image: "{{ .Values.api.image.repository }}:{{ .Values.version }}"
           imagePullPolicy: {{ .Values.api.image.pullPolicy }}
+          lifecycle:
+            preStop:
+              # Give the ALB ~15s to deregister this pod before SIGTERM fires.
+              # The total graceful window is terminationGracePeriodSeconds (60s) minus
+              # this sleep, leaving ~45s for ASP.NET Core to drain active SSE connections.
+              exec:
+                command: ["sleep", "15"]
           livenessProbe:
             httpGet:
               path: /health
@@ -82,7 +94,10 @@ spec:
 {{- include "exceptionless.otel-env" . | indent 12 }}
             - name: RunJobsInProcess
               value: 'false'
-            - name: EnableWebSockets
+            # SSE rollout prerequisite: Azure Application Gateway for Containers Ingress API
+            # does not support the routeTimeout=0s override required for long-lived SSE streams.
+            # Keep push disabled here until this route moves to Gateway API + RoutePolicy.
+            - name: EnablePush
               value: 'false'
 {{- if (empty .Values.storage.connectionString) }}
           volumeMounts:
@@ -163,6 +178,8 @@ metadata:
     alb.networking.azure.io/alb-namespace: {{ .Values.ingress.albNamespace }}
     alb.networking.azure.io/alb-frontend: {{ template "exceptionless.fullname" . }}-fe
     cert-manager.io/cluster-issuer: {{ .Values.ingress.clusterIssuer }}
+    # SSE is not safe to enable behind the current AGC Ingress API path.
+    # Migrate to Gateway API and attach a RoutePolicy with routeTimeout: 0s before enabling push.
 spec:
   ingressClassName: azure-alb-external
   tls:

src/Exceptionless.Core/Bootstrapper.cs

@@ -224,8 +224,8 @@ public static void LogConfiguration(IServiceProvider serviceProvider, AppOptions
         if (String.IsNullOrEmpty(appOptions.StorageOptions.Provider))
             logger.LogWarning("Distributed storage is NOT enabled on {MachineName}", Environment.MachineName);
 
-        if (!appOptions.EnableWebSockets)
-            logger.LogWarning("Web Sockets is NOT enabled on {MachineName}", Environment.MachineName);
+        if (!appOptions.EnablePush)
+            logger.LogWarning("Real-time push (SSE) is NOT enabled on {MachineName}", Environment.MachineName);
 
         if (String.IsNullOrEmpty(appOptions.EmailOptions.SmtpHost))
             logger.LogWarning("Emails will NOT be sent until the SmtpHost is configured on {MachineName}", Environment.MachineName);

src/Exceptionless.Core/Configuration/AppOptions.cs

@@ -55,7 +55,11 @@ public class AppOptions
 
     public bool EnableRepositoryNotifications { get; internal set; }
 
-    public bool EnableWebSockets { get; internal set; }
+    /// <summary>
+    /// Controls whether real-time push (SSE) is enabled. Reads from either 'EnablePush'
+    /// or legacy 'EnableWebSockets' config key for backward compatibility.
+    /// </summary>
+    public bool EnablePush { get; internal set; }
 
     public string? Version { get; internal set; }
 
@@ -111,7 +115,8 @@ public static AppOptions ReadFromConfiguration(IConfiguration config)
         options.BulkBatchSize = config.GetValue(nameof(options.BulkBatchSize), 1000);
 
         options.EnableRepositoryNotifications = config.GetValue(nameof(options.EnableRepositoryNotifications), true);
-        options.EnableWebSockets = config.GetValue(nameof(options.EnableWebSockets), true);
+        // Support both new 'EnablePush' and legacy 'EnableWebSockets' config keys
+        options.EnablePush = config.GetValue(nameof(options.EnablePush), config.GetValue("EnableWebSockets", true));
 
         try
         {

src/Exceptionless.Core/Utility/AppDiagnostics.cs

@@ -124,6 +124,11 @@ public GaugeInfo(Meter meter, string name)
 
     internal static readonly Counter<int> SavedViewsSize = Meter.CreateCounter<int>("ex.savedviews.size", description: "Size of user saved views");
     internal static readonly Counter<int> SavedViewsViewTypeSize = Meter.CreateCounter<int>("ex.savedviews.viewtype.size", description: "Size of user saved views by view type");
+
+    internal static readonly Counter<int> PushSseConnectionsOpened = Meter.CreateCounter<int>("ex.push.connections.sse.opened", description: "SSE push connections opened");
+    internal static readonly Counter<int> PushSseConnectionsClosed = Meter.CreateCounter<int>("ex.push.connections.sse.closed", description: "SSE push connections closed");
+    internal static readonly Counter<int> PushWebSocketConnectionsOpened = Meter.CreateCounter<int>("ex.push.connections.websocket.opened", description: "WebSocket push connections opened");
+    internal static readonly Counter<int> PushWebSocketConnectionsClosed = Meter.CreateCounter<int>("ex.push.connections.websocket.closed", description: "WebSocket push connections closed");
 }
 
 public static class MetricsClientExtensions

src/Exceptionless.Web/Bootstrapper.cs

@@ -14,6 +14,7 @@ public class Bootstrapper
 {
     public static void RegisterServices(IServiceCollection services, AppOptions appOptions, ILoggerFactory loggerFactory)
     {
+        services.AddSingleton<SseConnectionManager>();
         services.AddSingleton<WebSocketConnectionManager>();
         services.AddSingleton<MessageBusBroker>();
 

src/Exceptionless.Web/ClientApp.angular/components/websocket/websocket-service.js

@@ -1,6 +1,7 @@
 (function () {
     "use strict";
 
+    // Deprecated: keep the legacy Angular client on WebSocket during the SSE rollout.
     angular
         .module("exceptionless.websocket", ["app.config", "exceptionless", "exceptionless.auth"])
         .factory("websocketService", function ($ExceptionlessClient, $rootScope, $timeout, authService, BASE_URL) {