Azure-functions-host: AppInsights loglevel problems (requests and/or traces)

[cannehag]

Functions Version 3
Application Insights 2.10.0

I'm trying to understand how logsettings work.
I would like function invocation to be logged as a requests, but turn off tracing.
From what I have tested it seems that loglevel needs to be set to Information for the request logging to work, but that will also enable all tracing, which will be a lot of not needed data.

Is there a way to configure appinsights logging to log requests but not traces ?

[ankitkumarr]

@brettsam, do you know if this is possible today?

I know we have options to disable live metrics, dependency tracking and perf counters. But do we allows disabling TraceTelemetry?

[brettsam]

Results are logged with a category of Host.Results (see here). So, you can set a default log level of None, but then set Host.Results to Information. That will cause everything but the results to be ignored. I just gave this a try and it looks like it gives you what you're looking for.

{
  "version": "2.0",
  "logging": {
    "logLevel": {
      "default": "None",
      "Host.Results": "Information"
    },
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": false
      }
    }
  }
}

[ankitkumarr]

Thanks Brett! @cannehag, please let us know if that works for you.

[cannehag]

Thank you @ankitkumarr & @brettsam, this seems to work fine. But it seems to also have an effect on the dependency logging which I still would like to use. Is there a way to keep that ?

I really would like all the logging (request, exceptions, dependencies, customevents, perf counters etc), but NOT the traces.

[JonasSamuelsson]

Any updates on this one?

[cannehag]

I just tried this again using:
Azure Functions Core Tools (3.0.2245 Commit hash: 1d094e2f3ef79b9a478a1621ea7ec3f93ac1910d)
Function Runtime Version: 3.0.13139.0

My host.json:

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": false
       }
    },
    "logLevel": {
       "default": "Warning",
       "Host.Results": "Information"
    }
  }
}

When looking at appinsights, now I only get traces but NO requests. Shouldn't it be the opposite ?
@brettsam @ankitkumarr

[brettsam]

I just tried this locally with your exact host.json and all of my requests are correctly written to App Insights.

A couple things to double-check:

1. That you have APPINSIGHTS_INSTRUMENTATIONKEY set in your local.settings.json (I assume you do if you see traces)
2. That you wait a bit for the telemetry to flush. If you kill the process too quickly you may miss them and unless you exit gracefully (I believe ctrl+c will do this) the in-memory logs won't have flushed yet.
3. You wait ~5 minutes for the logs to show in App Insights.

[cannehag]

When digging deeper into our code we have some custom ITelemetryInitializer's that modified some properties on the Telemetry.
We also have a function that removes some customDimensions because we thought it wasn't necessary to log that much information.
Here I might have found the reason and I think it is because we remove the "Category" dimension. Do you know if that one needs to be there for the request logging to work @brettsam ?

[brettsam]

Category is required as all filtering is done on Category (for example -- Host.Results is a category, which is how the filtering knows whether to include it or not).

[cannehag]

Thank @brettsam. Is there any other customDimensions that are required that you know of? Otherwise I would consider this working now!

[cannehag]

One follow up question though @brettsam. Do you know if it is possible to wildcard the logsettings.
Traces are logged with category set to "Function.[FunctionName]" and my trace logs have the category "Function.[FunctionName].User".

Is it possible to configure this so that only my custom logs are actually saved. Like this:

"logLevel": {
"default": "Warning",
"Function.*.User": "Information",
"Host.Results": "Information"
}

[ThejaChoudary]

@brettsam Any information we need to provide further.

[brettsam]

Unfortunately, wildcards are not supported -- we rely on the default .NET Core log filtering (https://docs.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-3.1#how-filtering-rules-are-applied) which takes the longest match.

[ThejaChoudary]

@cannehag hope the above explanation answered your question.Proceeding to close the issue ,please feel free to get back to us if you have any queries further.Thank You!