.Net core log Startup errors to app insights

Question

I'm trying to log any startup errors but the logs are not flowing into application insights. I tried configuring app insights in program.cs but still I don't see any logs.

public static IHostBuilder CreateHostBuilder(string[] args) =>

    Host.CreateDefaultBuilder(args)
        .ConfigureLogging(logging =>
        {
            logging.ClearProviders();
            logging.AddApplicationInsights();
            logging.SetMinimumLevel(LogLevel.Information);
        });

Answer 1

By default it is not supported to handle exceptions from application startup, see this link.

What I did to get the logs into the application insights is to add a try/catch block in the Main of Program.cs and initialize the TelemetryClient manually.

See the following code:

    public static void Main(string[] args)
    {
        try 
        {
            CreateHostBuilder(args)
                .Build().Run();
        }
        catch(Exception ex) 
        {
            TelemetryConfiguration telemetryConfiguration = TelemetryConfiguration.CreateDefault();
            telemetryConfiguration.ConnectionString = "application-insights-connection-string";
            var telemetryClient = new TelemetryClient(telemetryConfiguration);
            telemetryClient.TrackException(ex);
            telemetryClient.Flush();
            throw;
        }
    }