Filter out health check transactions

[TomRoelofsWhyellow]

Package

Sentry.AspNetCore

.NET Flavor

.NET

.NET Version

6.0.0

OS

Any (not platform specific)

SDK Version

4.4.0

Self-Hosted Sentry Version

No response

Steps to Reproduce

1. Enable inbound filter for filtering out health check transactions
2. Create a health check endpoint (e.g. /healthcheck/database)
3. Assure that the health check is unhealthy
4. Perform a health check call to the endpoint

Expected Result

According to the docs (https://docs.sentry.io/product/data-management-settings/filtering/#transactions-coming-from-health-check), the health check transaction should be filtered out.

Number of other things I've tried:

1. Add SetBeforeSendTransaction and SetBeforeSend. Tried to filter on Transaction Name/Tags.

options.SetBeforeSendTransaction((sentryTransaction, _) => { return sentryTransaction.Name.Contains("healthcheck") ? null : sentryTransaction; });

2. Add TracesSampler

options.TracesSampler = samplingContext => { return samplingContext.TransactionContext.Name.Contains("healthcheck") ? 0 : 1; };

When I check the logs, it says the events/transactions are dropped, but I'm still receiving them in Sentry.

Actual Result

The health check is not filtered out.

[bitsandfoxes]

So it looks like our docs are ahead of our implementation! I don't find anything related to heathcheck in our SDK. We're going to put that on our To-Do.

[TomRoelofsWhyellow]

Are there any options to filter them out? This is depleting my performance units within a few days, because I have multiple health endpoints.

[bitsandfoxes]

You should definitely be able to filter those. The automatically created transaction's name should be in the format {method} {route} e.g. GET /pets/{id}. Can you confirm this?
Returning null drops the event.
The only way I see your filter not work would be if the SDK fails to extract the route from the route template.

[TomRoelofsWhyellow]

Yes, the format is indeed {method} {route}. I debugged the BeforeSend/BeforeSendTransaction/TracesSampler filters and the routes do get extracted correctly.

I've noticed that even after dropping a transaction, still some tracing information is sent to Sentry. Does this count towards my performance units limit?

[bitsandfoxes]

With the transaction dropped we update the client report. You can see that here:

sentry-dotnet/src/Sentry/SentryClient.cs

Lines 172 to 178 in 7213a8c

	processedTransaction = BeforeSendTransaction(processedTransaction, hint);
	if (processedTransaction is null) // Rejected transaction
	{
	_options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.BeforeSend, DataCategory.Transaction);
	_options.LogInfo("Transaction dropped by BeforeSendTransaction callback.");
	return;
	}

This does not count towards your quota.

[TomRoelofsWhyellow]

Okay, I'll check if the filters are working once I have performance units again.