Is it possible to exclude a url from Application Insights?

My team had a similiar situation where we needed to filter out urls that were successful image requests (we had a lot of these which made us hit the 30k datapoints/min limit).

We ended up using a modified version of the class in Sergey Kanzhelevs blog post to filter these out.

We created a RequestFilterChannel class which is an instance of ServerTelemetryChannel and extended the Send method. In this method we test each telemetry item to be sent to see if it is an image request and if so, we prevent it from being sent.

public class RequestFilterChannel : ITelemetryChannel, ITelemetryModule
{
    private ServerTelemetryChannel channel;

    public RequestFilterChannel()
    {
        this.channel = new ServerTelemetryChannel();
    }

    public void Initialize(TelemetryConfiguration configuration)
    {
        this.channel.Initialize(configuration);
    }

    public void Send(ITelemetry item)
    {
        if (item is RequestTelemetry)
        {
            var requestTelemetry = (RequestTelemetry) item;

            if (requestTelemetry.Success && isImageRequest((RequestTelemetry) item))
            {
                // do nothing
            }
            else
            {
                this.channel.Send(item); 
            }
        }
        else
        {
            this.channel.Send(item);
        }
    }

    public bool? DeveloperMode
    {
        get { return this.channel.DeveloperMode; }
        set { this.channel.DeveloperMode = value; }
    }

    public string EndpointAddress
    {
        get { return this.channel.EndpointAddress; }
        set { this.channel.EndpointAddress = value; }
    }

    public void Flush()
    {
        this.channel.Flush();
    }

    public void Dispose()
    {
        this.channel.Dispose();
    }

    private bool IsImageRequest(RequestTelemetry request)
    {
        if (request.Url.AbsolutePath.StartsWith("/image.axd"))
        {
            return true;
        }

        return false;
    }
}

Once the class has been created you need to add it to your ApplicationInsights.config file.

Replace this line:

<TelemetryChannel Type="Microsoft.ApplicationInsights.WindowsServer.TelemetryChannel.ServerTelemetryChannel, Microsoft.AI.ServerTelemetryChannel"/>

with a link to your class:

<TelemetryChannel Type="XXX.RequestFilterChannel, XXX" />  

Alternatively, you can disable the automated request collection and keep only exception auto-collection, just remove the RequestTrackingModule line from applicationinsights.config.

If you still need to collect some of the requests, not just filter all out, you can then call TrackRequest() (in the object of TelemetryClient class) from your code in the appropriate place after you know that you certainly need to log this request to AI.

Update: Filtering feature has been released some time ago and allows for exclusion of certain telemetry items way easier.

Out of the box it is not supported. Sampling feature is coming but that would not be configurable by specific url. You can implement your own channel that would have your custom filtering. Basically your channel will get event to be sent, you check if you want to send it or not and then if yes pass to standard AI channel. Here you can read more about custom channels.

There are two things that changed since this blog post has been written:

• channel should implement only ITelemetryChannel interface (ISupportConfiguration was removed)
• and instead of PersistenceChannel you should use Microsoft.ApplicationInsights.Extensibility.Web.TelemetryChannel

UPDATE: Latest version has filtering support: https://azure.microsoft.com/en-us/blog/request-filtering-in-application-insights-with-telemetry-processor/