Applications insights sampling not working for a C# function app

Question

I have a C# function app. I am using Application Insights which is Workspace-based. I only want to keep Trace and Exception details. Everything else I don't want. I think the host.json file below is correct

{
  "version": "2.0",
    "logging": {
    "logging": {
      "logLevel": {
        "default": "Warning",
        "Function": "Warning",
        "Host.Aggregator": "Error",
        "Host.Results": "Warning",
        "Microsoft": "Error",
        "Worker": "Error"
      },
      "applicationInsights": {
        "samplingSettings": {
          "isEnabled": true,
          "initialSamplingPercentage": 0,
          "excludedTypes": "Trace;Exception"
        },
        "enableLiveMetrics": false,
        "enableDependencyTracking": false,
        "enablePerformanceCountersCollection": false,
        "httpAutoCollectionOptions": {
          "enableHttpTriggerExtendedInfoCollection": false,
          "enableW3CDistributedTracing": false,
          "enableResponseHeaderInjection": false
        }
      }
    }
  }
}

When I look at estimated costs within the workspace I am being billed for other things. The things I actually want are less than half my usage!

Answer 1

Hi @RobertTheBruce

You actual configured sampleSettings incorrectly. To only keep trace and exception and trace details, it should be configured with includeTypes set:

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "initialSamplingPercentage": 100,
        "maxSamplingPercentage": 100,
        "minSamplingPercentage": 100,
        "samplingPercentageIncreaseTimeout": "00:00:00",
        "samplingPercentageDecreaseTimeout": "00:00:00",
        "includedTypes": "Trace;Exception",
        "excludedTypes": ""
      }
    }
  }
}

In this example, the includedTypes property is set to Trace;Exception, which means that only trace and exception details will be included in the telemetry data. The excludedTypes property is set to an empty string, which means that no other telemetry types will be excluded.

You can find more information about configuring sampling in Application Insights in the official documentation.