How do I find application insights logs for specific ILogger<T>

Question

I use asp.net core logging like this:

public class MyClass
{
    private readonly ILogger<MyClass> _logger;
    public readonly EventId NoEntryFoundEventId = new EventId(1, "No Entry Found");

    public MyClass(ILogger<MyClass> logger)
    {
        _logger = logger;
    }

    public void Foo(decimal entryId)
    {
        _logger.LogError(NoEntryFoundEventId, "MyCustomMessage\t: Entry ID: {EntryId}", entryId);         
    }
}

An I setup the logger like this:

services.AddApplicationInsightsTelemetry();

loggerFactory.AddApplicationInsights(app.ApplicationServices, LogLevel.Information)

How do I find the logs for MyClass in Azure portal?

Answer 1

As far as I understand, you want to find the log entries in Application Insights that are specifically linked to your class MyClass.

It is in the Property "CategoryName".

Getting Started with Application Insights for ASP.NET Core

Your program.cs should look something like this

public static IWebHost BuildWebHost(string[] args) =>
  WebHost.CreateDefaultBuilder(args)
    .UseStartup<Startup>()
    .UseApplicationInsights()
    .Build();

Then link the ASP.NET ILogger to Application Insights

public void Configure(IApplicationBuilder app, IHostingEnvironment env, 
    ILoggerFactory loggerFactory)
{
/*...existing code..*/
        loggerFactory.AddApplicationInsights(app.ApplicationServices, LogLevel.Warning);
}

If you set it up like this, your ILogger will automatically use the full name of MyClass as a category name, and you will see that in Application Insights under the property "CategoryName".

https://github.com/Microsoft/ApplicationInsights-aspnetcore/tree/develop/src/Microsoft.ApplicationInsights.AspNetCore/Logging/Implementation

private void PopulateTelemetry(ITelemetry telemetry, 
   IReadOnlyList<KeyValuePair<string, object>> stateDictionary, EventId eventId)
    {
        IDictionary<string, string> dict = telemetry.Context.Properties;
        dict["CategoryName"] = this.categoryName;
...

See also this question for an image on how this will look in Application Insights: Using Application Insights with ILoggerFactory (Image is taken directly from this answer, please tell me if this is not allowed and I will remove it)

The data is added as a "custom property" and can be filtered like that in the portal:

Some more info: https://docs.microsoft.com/en-us/azure/application-insights/app-insights-api-custom-events-metrics#properties https://docs.microsoft.com/en-us/azure/application-insights/app-insights-analytics-tour#custom-properties-and-measurements