Duplicate log entries in Application Insights with Isolated Azure Functions with ASP.NET Core Integration and Serilog

Question

I have a .NET 8 Azure Functions project in an isolated worker process with ASP.NET Core Integration. For logging I want to use Serilog and the ApplicationInsights sink so I'm able to log scoped properties.

In my local settings I have APPINSIGHTS_INSTRUMENTATIONKEY and APPLICATIONINSIGHTS_CONNECTION_STRING defined and my Program.cs looks like this:

var host = new HostBuilder()
    .ConfigureFunctionsWebApplication(worker => {})
    .ConfigureAppConfiguration((hostingContext, configBuilder) =>
    {
        configBuilder.AddJsonFile("local.settings.json", optional: true, reloadOnChange: true);
    })
    .ConfigureServices((hostBuilderContext, services) =>
    {
        services.AddApplicationInsightsTelemetryWorkerService();
        services.ConfigureFunctionsApplicationInsights();
    })
    .UseSerilog((context, provider, configuration) =>
    {
        var telemetryClient = provider.GetRequiredService<TelemetryClient>();
       
        configuration
            .Enrich.WithMachineName()
            .Enrich.WithEnvironmentName()
            .Enrich.FromLogContext()
            .WriteTo.ApplicationInsights(telemetryClient, TelemetryConverter.Traces)
            .WriteTo.Console();
    })
    .Build();

await host.RunAsync();

host.json:

{
    "version": "2.0",
    "extensions": {
        "durableTask": {
            "storageProvider": {
                "type": "mssql",
                "connectionStringName": "EnterpriseResourcePlanningServicesDbConnection",
                "taskEventLockTimeout": "00:02:00",
                "createDatabaseIfNotExists": true,
                "schemaName": "dt"
            }
        }
    }
}

This results in duplicate logging (see image below) from my local development machine. What am I missing here? How is it possible that I get duplicate log entries? The one with [INF] isn't showing any scoped data under customDimensions where this is the case for the other log item (not showing on image)

I also tried to clear all the providers in ConfigureLogging on the host builder but no difference...

Example of duplicate log entry

Answer 1

The below code worked for me without generating Duplicate log entries:

Program.cs:

using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Serilog;

var host = new HostBuilder()
    .ConfigureFunctionsWebApplication()
    .ConfigureAppConfiguration((ri_cxt, configBuilder) =>
    {
        configBuilder.AddJsonFile("local.settings.json", optional: true, reloadOnChange: true);
    })
    .ConfigureServices((ri_cxt, ri_services) =>
    {
        IConfiguration ri_confg = ri_cxt.Configuration;
        ri_services.AddLogging(loggingBuilder =>
        {
            var con_strg = ri_confg["rith_con_str"];
            var ri_logconfg = new LoggerConfiguration()
                .MinimumLevel.Information()
                .Enrich.FromLogContext();
            ri_logconfg.WriteTo.ApplicationInsights(con_strg, TelemetryConverter.Traces);
            loggingBuilder.AddSerilog(ri_logconfg.CreateLogger());
        });
        ri_services.AddApplicationInsightsTelemetryWorkerService();
        ri_services.ConfigureFunctionsApplicationInsights();
    })
    .Build();
host.Run();

host.json:

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "enableLiveMetricsFilters": true,
      "samplingSettings": {
        "isEnabled": false,
        "excludedTypes": "Request"
      }
    },
    "console": {
      "isEnabled": true,
      "logLevel": {
        "default": "Information"
      }
    }
  }
}

local.settings.json:

{
    "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
    "rith_con_str": "InstrumentationKey=4f7edc2b73;IngestionEndpoint=https://eastus-8.in.applicationinsights.azure.com/;LiveEndpoint=https://eastus.livediagnostics.monitor.azure.com/;ApplicationId=843db447-2af3-4597bc"
  }
}

Packages in csproj:

<ItemGroup>
    <FrameworkReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.21.0" />
    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http" Version="3.1.0" />
    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore" Version="1.2.0" />
    <PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" Version="1.17.0" />
    <PackageReference Include="Microsoft.ApplicationInsights.WorkerService" Version="2.22.0" />
    <PackageReference Include="Microsoft.Azure.Functions.Worker.ApplicationInsights" Version="1.2.0" />
    <PackageReference Include="Microsoft.Extensions.Configuration.UserSecrets" Version="8.0.0" />
    <PackageReference Include="Serilog.Formatting.Compact" Version="2.0.0" />
    <PackageReference Include="Serilog.Sinks.ApplicationInsights" Version="4.0.0" />
    <PackageReference Include="Serilog.Extensions.Logging" Version="3.0.2" />
    <PackageReference Include="Serilog.Sinks.Console" Version="5.0.1" />
</ItemGroup>

Function1.cs:

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Logging;

namespace FunctionApp191
{
    public class Function1
    {
        private readonly ILogger<Function1> ri_log;

        public Function1(ILogger<Function1> logger)
        {
            ri_log = logger;
        }

        [Function("Function1")]
        public IActionResult Run([HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequest req)
        {
            ri_log.LogInformation("Hello Rithwik Bojja, Hope you are Rocking!!!");
            return new OkObjectResult("Function Executed!!!");
        }
    }
}

Output:

By following above program.cs and host.json and other code you will able to see only entries which you are logging and no duplicates are created.