feat: Add Azure Monitor OpenTelemetry Profiler for container deployments (#1107)

## Summary

Adds the [Azure Monitor OpenTelemetry
Profiler](https://github.com/Azure/azuremonitor-opentelemetry-profiler-net)
(`Azure.Monitor.OpenTelemetry.Profiler`) to enable Application Insights
profiling and [Code
Optimizations](https://learn.microsoft.com/en-us/azure/azure-monitor/optimization-insights/code-optimizations-profiler-overview)
in production.

## Why this package (not
`Microsoft.ApplicationInsights.Profiler.AspNetCore`)

The app already uses `Azure.Monitor.OpenTelemetry.AspNetCore` (OTel
distro). Microsoft's docs list two profiler paths:
- **Old SDK path**: `Microsoft.ApplicationInsights.Profiler.AspNetCore`
+ `AddServiceProfiler()` — uses a native uploader binary, incompatible
with chiseled containers
- **New OTel path**: `Azure.Monitor.OpenTelemetry.Profiler` +
`AddAzureMonitorProfiler()` ← **this PR** — uses EventPipe (pure
in-process), compatible with chiseled images

## Changes

- **`Directory.Packages.props`**: Add
`Azure.Monitor.OpenTelemetry.Profiler 1.0.0-beta9` to Central Package
Management (prerelease-only; TODO comment added to update at GA)
- **`EssentialCSharp.Web.csproj`**: Reference the new package
- **`Program.cs`**: Chain `.AddAzureMonitorProfiler()` onto
`UseAzureMonitor()` — profiler only activates when
`APPLICATIONINSIGHTS_CONNECTION_STRING` is set (production only, never
local/OTLP)
- **`appsettings.Development.json`**: Add `Debug` log level for profiler
namespaces for local diagnostics

## Testing

| Test | Result |
|---|---|
| `dotnet run` with fake connection string | ✅ Profiler agent loads,
initializes, CPU sampling begins — fails only on invalid key (expected)
|
| Docker (`noble-chiseled-extra`) with fake key | ✅ Identical behavior —
no native dependency errors, no shell-not-found failures |

## What this enables in production

Once `APPLICATIONINSIGHTS_CONNECTION_STRING` is set in the ACA
deployment config:
- **Sampling trigger**: Profiles ~2 min/hour automatically
- **CPU trigger**: Profiles when CPU >80%
- **Memory trigger**: Profiles when memory >80%
- **Code Optimizations**: AI-based perf insights in Azure portal (works
because we use default storage, not BYOS)

## Notes
- No BYOS (Bring Your Own Storage) — intentional; BYOS would disable
Code Optimizations
- No manual request tracking needed — ASP.NET Core auto-tracks requests
- Trigger thresholds can be tuned in Azure portal → App Insights →
Performance → Profiler → Triggers

---------

Co-authored-by: Copilot Autofix powered by AI <223894421+github-code-quality[bot]@users.noreply.github.com>

Author: BenjaminMichaelis

Directory.Packages.props

@@ -22,6 +22,8 @@
     <PackageVersion Include="Azure.Extensions.AspNetCore.Configuration.Secrets" Version="1.5.1" />
     <PackageVersion Include="Azure.Identity" Version="1.21.0" />
     <PackageVersion Include="Azure.Monitor.OpenTelemetry.AspNetCore" Version="1.5.0" />
+    <!-- TODO: update to stable release when Azure.Monitor.OpenTelemetry.Profiler reaches GA -->
+    <PackageVersion Include="Azure.Monitor.OpenTelemetry.Profiler" Version="1.0.0-beta9" />
     <PackageVersion Include="TUnit" Version="1.40.5" />
     <PackageVersion Include="EssentialCSharp.Shared.Models" Version="$(ToolingPackagesVersion)" />
     <PackageVersion Include="HtmlAgilityPack" Version="1.12.4" />

EssentialCSharp.Web/EssentialCSharp.Web.csproj

@@ -38,6 +38,7 @@
     <PackageReference Include="Azure.Extensions.AspNetCore.DataProtection.Keys" />
     <PackageReference Include="Azure.Identity" />
     <PackageReference Include="Azure.Monitor.OpenTelemetry.AspNetCore" />
+    <PackageReference Include="Azure.Monitor.OpenTelemetry.Profiler" />
     <PackageReference Include="EssentialCSharp.Shared.Models" />
     <PackageReference Include="HtmlAgilityPack" />
     <PackageReference Include="IntelliTect.Multitool" />

EssentialCSharp.Web/Program.cs

@@ -19,6 +19,7 @@
 using Microsoft.AspNetCore.Identity.UI.Services;
 using Microsoft.AspNetCore.RateLimiting;
 using Azure.Monitor.OpenTelemetry.AspNetCore;
+using Azure.Monitor.OpenTelemetry.Profiler;
 using Microsoft.AspNetCore.DataProtection;
 using Microsoft.AspNetCore.Diagnostics;
 using Microsoft.AspNetCore.Diagnostics.HealthChecks;
@@ -90,7 +91,7 @@ private static void Main(string[] args)
             });
 
         if (useAzureMonitor)
-            otel.UseAzureMonitor();
+            otel.UseAzureMonitor().AddAzureMonitorProfiler();
         else if (useOtlp)
             otel.UseOtlpExporter();
 
@@ -511,7 +512,7 @@ await McpJsonRpcResponseWriter.WriteErrorAsync(
         }
         app.UseStaticFiles();
 
-        app.UseRouting();
+        app.UseRouting();
 
         app.UseWhen(
             context => context.Request.Path.StartsWithSegments("/mcp"),
@@ -542,10 +543,10 @@ await McpJsonRpcResponseWriter.WriteErrorAsync(
                 await next(context);
             }));
 
-        app.UseRateLimiter();
-
-        app.UseAuthorization();
-        app.UseOutputCache();
+        app.UseRateLimiter();
+
+        app.UseAuthorization();
+        app.UseOutputCache();
 
         app.UseMiddleware<ReferralMiddleware>();
 
@@ -584,13 +585,23 @@ await McpJsonRpcResponseWriter.WriteErrorAsync(
         try
         {
             SitemapXmlHelpers.EnsureSitemapHealthy(siteMappingService.SiteMappings.ToList());
-            LogSitemapValidationSucceeded(logger);
-        }
-        catch (Exception ex)
-        {
-            LogSitemapValidationFailed(logger, ex);
-            // Continue startup even if sitemap validation fails
-        }
+            LogSitemapValidationSucceeded(logger);
+        }
+        catch (InvalidOperationException ex)
+        {
+            LogSitemapValidationFailed(logger, ex);
+            // Continue startup even if sitemap validation fails
+        }
+        catch (ArgumentException ex)
+        {
+            LogSitemapValidationFailed(logger, ex);
+            // Continue startup even if sitemap validation fails
+        }
+        catch (FormatException ex)
+        {
+            LogSitemapValidationFailed(logger, ex);
+            // Continue startup even if sitemap validation fails
+        }
 
         app.Run();
     }
@@ -604,11 +615,11 @@ private static bool IsMcpTransportRequest(HttpRequest request) =>
     [LoggerMessage(Level = LogLevel.Error, Message = "Unhandled exception on {Path}")]
     private static partial void LogUnhandledException(ILogger<Program> logger, Exception? exception, PathString path);
 
-    [LoggerMessage(Level = LogLevel.Information, Message = "Sitemap validation completed successfully during application startup")]
-    private static partial void LogSitemapValidationSucceeded(ILogger<Program> logger);
-
-    [LoggerMessage(Level = LogLevel.Error, Message = "Failed to validate sitemap during application startup")]
-    private static partial void LogSitemapValidationFailed(ILogger<Program> logger, Exception exception);
+    [LoggerMessage(Level = LogLevel.Information, Message = "Sitemap validation completed successfully during application startup")]
+    private static partial void LogSitemapValidationSucceeded(ILogger<Program> logger);
+
+    [LoggerMessage(Level = LogLevel.Error, Message = "Failed to validate sitemap during application startup")]
+    private static partial void LogSitemapValidationFailed(ILogger<Program> logger, Exception exception);
 
     [LoggerMessage(Level = LogLevel.Warning, Message = "Ignoring invalid TryDotNet origin in CSP: {Origin}")]
     private static partial void LogIgnoringInvalidTryDotNetOrigin(ILogger logger, string origin);

EssentialCSharp.Web/appsettings.Development.json

@@ -3,7 +3,9 @@
   "Logging": {
     "LogLevel": {
       "Default": "Information",
-      "Microsoft.AspNetCore": "Warning"
+      "Microsoft.AspNetCore": "Warning",
+      "Microsoft.ServiceProfiler": "Debug",
+      "Azure.Monitor.OpenTelemetry.Profiler": "Debug"
     }
   },
   "ConnectionStrings": {