Application Insights for WebAPI application - azure

Question

Is it possible to tell Application Insights to use a different InstrumentationKey depending on the request URL?
Our application works with different clients and we want to separate the logs for them in different instances of Application Insights.
Url format: https://webapi.com/v1/{client_name}/bla/bla
It would be great to setup configuration to select InstrumentationKey by client_name from request.

Answer 1

If the goal is to send different telemetry items to different instrumentation key, the correct way to achieve that is by modifying the individual item with a TelemetryInitializer to have the correct ikey.
An initializer like the following:
item.Context.InstrumentationKey = ikey.
This initializer should access HttpContext and decide the ikey dynamically from request route/other params.
Modifying TC.Active is not recommended for this purpose as its a global shared setting.
(This is not a very common use case - but there are teams inside Microsoft who does this for PROD scale apps)

Answer 2

You can do that. If you have a logger, have the ApplicationInsightsKey parameter-ized and pass the Key for the client on every call, or inject it on load if your application is tenant based.
Checkout the Docs here: Separating telemetry from Development, Test, and Production
Microsoft.ApplicationInsights.Extensibility.
TelemetryConfiguration.Active.InstrumentationKey = <App-Insights-Key-for-the-client>
Just change the Application Insights key before logging and it will do the job.

Answer 3

It would be great to setup configuration to select InstrumentationKey
by client_name from request.
You can dynamically select the ikey as per the client_name from the request. First, you need to get the request url, then check the client_name.
To do that, you can add the following code to the Global.asax file:
void Application_BeginRequest(Object source, EventArgs e)
{
var app = (HttpApplication)source;
//get the request url
var uriObject = app.Context.Request.Url.ToString();
if (uriObject.Contains("/client_name_1"))
{
Microsoft.ApplicationInsights.Extensibility.
TelemetryConfiguration.Active.InstrumentationKey = "ikey_1";
}
else if (uriObject.Contains("/client_name_2"))
{
Microsoft.ApplicationInsights.Extensibility.
TelemetryConfiguration.Active.InstrumentationKey = "ikey_2";
}
else
{
Microsoft.ApplicationInsights.Extensibility.
TelemetryConfiguration.Active.InstrumentationKey = "ikey_3";
}
}
The test result:
But I want to say we rarely use 1 more ikeys in one environment. If your goal is to make the data not being cluttered, I suggest you can use only 1 ikey, and then use Kusto query for your purpose.

Answer 4

Thanks to the answers from #cijothomas and #danpop (link) I was able to understand the whole picture.
Step 1: Create custom ITelemetryInitializer (Microsoft Documentation):
public class MyTelemetryInitializer : ITelemetryInitializer
{
public void Initialize(ITelemetry telemetry)
{
var appKey = CallContext.LogicalGetData("ApplicationKey")?.ToString();
switch (appKey)
{
case "App1":
telemetry.Context.InstrumentationKey = "d223527b-f34e-4c47-8aa8-1f21eb0fc349";
return;
default:
telemetry.Context.InstrumentationKey = "f8ceb6cf-4357-4776-a2b6-5bbed8d2561c";
return;
}
}
}
Step 2: Register custom initializer:
<ApplicationInsights xmlns="http://schemas.microsoft.com/ApplicationInsights/2013/Settings">
<TelemetryInitializers>
<Add Type="Application.WebAPI.MyTelemetryInitializer, Application.WebAPI"/>
</TelemetryInitializers>
<!--<InstrumentationKey>f8ceb6cf-4357-4776-a2b6-5bbed8d2561c</InstrumentationKey>-->
</ApplicationInsights>
OR
protected void Application_Start()
{
// ...
TelemetryConfiguration.Active.TelemetryInitializers.Add(new MyTelemetryInitializer());
}
Step 3: Make some adjustments to the logger (source code taken from #danpop answer Logger target configuration):
var config = new LoggingConfiguration();
ConfigurationItemFactory.Default.Targets.RegisterDefinition("ai", typeof());
ApplicationInsightsTarget aiTarget = new ApplicationInsightsTarget();
aiTarget.InstrumentationKey = "your_key";
aiTarget.Name = "ai";
config.AddTarget("ai", aiTarget);
LogManager.Configuration = config;
ILogger configuration exmples: Log4Net, NLog, System.Diagnostics