Disable diagnostic events (#4542)

Author: liliankasem

release_notes.md

@@ -7,4 +7,5 @@
 
 #### Changes
 
-- Fix dotnet templates installation (#5358)
+- Fix dotnet templates installation (#4538)
+- Disable diagnostic events in local development by replacing the `IDiagnosticEventRepository` with a `DiagnosticEventNullRepository` (#4542)

src/Cli/func/Actions/HostActions/StartHostAction.cs

@@ -21,6 +21,7 @@
 using Microsoft.Azure.WebJobs.Script.Configuration;
 using Microsoft.Azure.WebJobs.Script.Description;
 using Microsoft.Azure.WebJobs.Script.WebHost;
+using Microsoft.Azure.WebJobs.Script.WebHost.Diagnostics;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
@@ -265,6 +266,9 @@ private async Task<IWebHost> BuildWebHost(ScriptApplicationHostOptions hostOptio
                     {
                         services.AddSingleton<IConfigureBuilder<IServiceCollection>>(_ => new DotNetIsolatedDebugConfigureBuilder());
                     }
+
+                    // We do not need diagnostic events for local development, so we replace it with a null repository
+                    services.AddSingleton<IDiagnosticEventRepository, DiagnosticEventNullRepository>();
                 })
                 .Build();
         }