Azure Application Insight logs only Warning and higher

Question

An Azure Function App (C# 8) logs to Azure Application Insights. While I can see all its log messages in the live window during "Test/Run", I find only part of these log messages when searching for them in "Application Insights - Logs - traces". And the messages which I find are at Warning level only (no exceptions happened, so not expected here). While entries of other items are even at Trace level (e.g. "Sending invocation id...")

Where do I have to configure what settings?

Answer 1

I have created an HTTP trigger function with a runtime stack of .NET 8.0.

• I have configured Application Insights using the instrumentation key in the code and able to retrieve logs in AppInsights.

function code:

using System;
using System.Net;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Http;
using Microsoft.Extensions.Logging;

namespace Company.Function
{
    public class HttpTrigger1
    {
        [Function("HttpTrigger1")]
        public HttpResponseData Run([HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequestData req)
        {
            try
            {
                _logger.LogInformation("C# HTTP trigger function processed a request.");

                throw new InvalidOperationException("This is a sample exception.");
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "An exception occurred.");
                var errorResponse = req.CreateResponse(HttpStatusCode.InternalServerError);
                errorResponse.WriteString("An error occurred. Please try again later.");
                return errorResponse;
            }
        }
    }
}

host.json:

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request"
      }
    },
    "logLevel": {
      "default": "Information",
      "MyNamespace.MyCustomExceptionCategory": "Error",
      "MyNamespace.MyInformationCategory": "Information",
      "MyNamespace.MyWarningCategory": "Warning"
    }
  }
}

Program.cs:

using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.ApplicationInsights;

var host = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults()
    .ConfigureServices(services => {
        services.AddLogging(loggingBuilder =>
        {
            loggingBuilder.AddApplicationInsights("your appinsights instrumentation key");
            loggingBuilder.AddFilter<ApplicationInsightsLoggerProvider>("", LogLevel.Information);
        });
    })
    .Build();
host.Run();

Application successfully deployed and able to see in function app. check below:

When I click on Test/Run ran successfully and get the Exception logs and Information logs in Application insights.

Output: