ASP.NET Core configuration preferentially treats appsettings file instead of IConfiguration

ASP.NET Core SDK only

Actual: AddApplicationInsightsTelemetry is “favoring” configuration from appsettings.json.

Expected: AddApplicationInsightsTelemetry should simply respect IConfiguration, which is fully controlled by application owner.

To Reproduce

See https://github.com/MicrosoftDocs/azure-docs/issues/90862

Rootcause: https://github.com/microsoft/ApplicationInsights-dotnet/blob/main/NETCORE/src/Microsoft.ApplicationInsights.AspNetCore/Extensions/DefaultApplicationInsightsServiceConfigureOptions.cs#L36-L43 ^ This first loads user’s IConfiguration, then loads appsettings.json. This causes appsettings.json to override.

https://github.com/microsoft/ApplicationInsights-dotnet/blob/main/NETCORE/src/Microsoft.ApplicationInsights.WorkerService/DefaultApplicationInsightsServiceConfigureOptions.cs#L31https://github.com/microsoft/ApplicationInsights-dotnet/blob/main/NETCORE/src/Microsoft.ApplicationInsights.WorkerService/DefaultApplicationInsightsServiceConfigureOptions.cs#L31

WorkerService does not have this issue. So, I think this added to maintain backward compatibility when the feature was added to AddApplicationInsightsTelemetry() to automatically read IConfiguration.

[pharring]

… I lost the ability to tweak the ‘options’ in conjunction with loading from the referenced instance of IConfiguration

Perhaps we need an overload of AddApplicationInsightsTelemetry that takes an IConfiguration and a delegate (Action<ApplicationInsightsServiceOptions>)

Alternatively, does this work:

services.AddApplicationInsightsTelemetry(options => 
{
    configuration.Bind("ApplicationInsights", options);
    // TODO: Modify options.DeveloperMode as required
});

where configuration is your configuration root object. If your code doesn’t already have it in hand, it may be available on the builder context object.

[bhehe]

Being new to AppInsights myself, I had to digest all of this and realized that I should be using the method signature which takes in my version of IConfiguration. The documentation does call it out but should likely better reinforce this concept and explain the behavior. I would expect IConfiguration to be used by default and for it to be the sole source of truth and never overridden by re-reading from appsettings.json as I have overloads i.e. the typical per-environment file approach.

What I found after switching to that method signature was that I lost the ability to tweak the ‘options’ in conjunction with loading from the referenced instance of IConfiguration - which I had been leveraging that to explicitly set the Developer Mode based on my own specific logic.

It seems like now I have to find the equivalent way to explicitly set it in my appsettings.json file - or overload files - otherwise it looks like I’d have to set if by code where I resolve & use the TelemetryConfiguration/Channel (I think). I’d much rather do it once in the same place I’m registering things.