Add a metrics wrapper

Author: andreasohlund

src/ServiceControl.Audit/Auditing/AuditIngestionMetrics.cs

@@ -0,0 +1,21 @@
+namespace ServiceControl.Audit.Auditing;
+
+using System.Diagnostics.Metrics;
+
+public class AuditIngestionMetrics
+{
+    public AuditIngestionMetrics(IMeterFactory meterFactory)
+    {
+        var meter = meterFactory.Create(MeterName, MeterVersion);
+        forwardedMessagesCounter = meter.CreateCounter<long>(CreateInstrumentName("forwarded"), description: "Audit ingestion forwarded message count");
+    }
+
+    public void IncrementMessagesForwarded(int count) => forwardedMessagesCounter.Add(count);
+
+    static string CreateInstrumentName(string instrumentName) => $"sc.audit.ingestion.{instrumentName}".ToLower();
+
+    readonly Counter<long> forwardedMessagesCounter;
+
+    const string MeterName = "Particular.ServiceControl.Audit";
+    const string MeterVersion = "0.1.0";
+}

src/ServiceControl.Audit/Auditing/AuditIngestor.cs

@@ -2,7 +2,6 @@
 {
     using System;
     using System.Collections.Generic;
-    using System.Diagnostics.Metrics;
     using System.Linq;
     using System.Threading.Tasks;
     using Infrastructure.Settings;
@@ -14,8 +13,7 @@
     using Persistence.UnitOfWork;
     using Recoverability;
     using SagaAudit;
-    using ServiceControl.Infrastructure;
-    using ServiceControl.Transports;
+    using Transports;
 
     public class AuditIngestor
     {
@@ -26,11 +24,13 @@ public AuditIngestor(
             IEnumerable<IEnrichImportedAuditMessages> auditEnrichers, // allows extending message enrichers with custom enrichers registered in the DI container
             IMessageSession messageSession,
             Lazy<IMessageDispatcher> messageDispatcher,
-            ITransportCustomization transportCustomization
+            ITransportCustomization transportCustomization,
+            AuditIngestionMetrics metrics
         )
         {
             this.settings = settings;
             this.messageDispatcher = messageDispatcher;
+            this.metrics = metrics;
             var enrichers = new IEnrichImportedAuditMessages[] { new MessageTypeEnricher(), new EnrichWithTrackingIds(), new ProcessingStatisticsEnricher(), new DetectNewEndpointsFromAuditImportsEnricher(endpointInstanceMonitoring), new DetectSuccessfulRetriesEnricher(), new SagaRelationshipsEnricher() }.Concat(auditEnrichers).ToArray();
 
             logQueueAddress = transportCustomization.ToTransportQualifiedQueueName(settings.AuditLogQueue);
@@ -52,7 +52,7 @@ public async Task Ingest(List<MessageContext> contexts)
                 if (settings.ForwardAuditMessages)
                 {
                     await Forward(stored, logQueueAddress);
-                    forwardedMessagesCounter.Add(stored.Count);
+                    metrics.IncrementMessagesForwarded(stored.Count);
                 }
 
                 foreach (var context in contexts)
@@ -131,8 +131,8 @@ public async Task VerifyCanReachForwardingAddress()
         readonly AuditPersister auditPersister;
         readonly Settings settings;
         readonly Lazy<IMessageDispatcher> messageDispatcher;
+        readonly AuditIngestionMetrics metrics;
         readonly string logQueueAddress;
-        readonly Counter<long> forwardedMessagesCounter = Telemetry.Meter.CreateCounter<long>(Telemetry.CreateInstrumentName("ingestion", "forwarded"), description: "Audit ingestion forwarded message count");
 
         static readonly ILog Log = LogManager.GetLogger<AuditIngestor>();
     }

src/ServiceControl.Audit/HostApplicationBuilderExtensions.cs

@@ -71,6 +71,8 @@ public static void AddServiceControlAudit(this IHostApplicationBuilder builder,
         NServiceBusFactory.Configure(settings, transportCustomization, transportSettings, onCriticalError, configuration);
         builder.UseNServiceBus(configuration);
 
+        services.AddSingleton<AuditIngestionMetrics>();
+
         if (!string.IsNullOrEmpty(settings.OtlpEndpointUrl))
         {
             if (!Uri.TryCreate(settings.OtlpEndpointUrl, UriKind.Absolute, out var otelMetricsUri))