Add Metrics API

[bruno-garcia]

Sentry is building a new metrics product: getsentry/sentry#58584

Note: We need to be clear that the API itself would be preview, perhaps through xml docs.

Developer Docs

https://develop.sentry.dev/sdk/metrics/

Progress in other SDKs

• Python:
  • trailblazer to dogfood/build the product...
  • Initial implementation
  • Metric Span Summaries
• PHP: Add support for Sentry Developer Metrics sentry-php#1619 (draft)
• Javascript: Metrics SDK v0 sentry-javascript#9691 (WIP)
  • feat(types): Add statsd envelope types sentry-javascript#9304
  • feat(metrics): Add interfaces for metrics sentry-javascript#9698
  • Browser: feat(browser): Add browser metrics sdk sentry-javascript#9794
• Rust: Add experimental metrics implementation sentry-rust#618

Testing / Dogfooding in .NET

Would be great to dogfood this through Symbol Collector which today uses StatsD and emits metrics

The mobile app also has some metrics but it just dumps the Extra on events (can see it anywhere other than individual events).

[bruno-garcia]

There are actually develop docs on this: https://develop.sentry.dev/delightful-developer-metrics/sending-metrics-sdk/

Please note this is very early stage so not worth adding a ton of tests, we could have this on a branch and ship alpha's from it for example

[bruno-garcia]

see also getsentry/sentry-python#2522

[bruno-garcia]

JS: getsentry/sentry-javascript#9691

[bruno-garcia]

getsentry/sentry-rust#618

[jamescrosswell]

Open Telemetry

Eventaully we might be able to build a bridge between Sentry's metrics and OpenTelemetry Metrics, if people wanted to use OpenTelemetry for instrumentation (similar to what we've done for Tracing)

Metric Types

For the following metric types:

• Counter: OpenTelemetry has a Counter
• Distribution: The closest thing OTel has is a Histogram
• Gauge: OpenTelemetry has a Gauge
• OpenTelemetry also has an UpDownCounter

Tags

Tags can be used to attach meta-data to metrics. These could be implemented using OpenTelemetry Attributes.

Additional Context

Sentry DDM allows associating code locations with metrics. This could be achieved by convention using an OpenTelemetry Attribute with a specific name. Note that attributes are provided on metric values, not on the metrics overall e.g. Counter.add in the Metrics API.

Timers

The OpenTelemetry docs don't mention anything like the Timers described in Sentry's DDMs... Although the timers themselves are just a mechanism to collect a fairly specific metric (the amount of time taken to execute a particular piece of code). So these could be implemented in the Sentry SDK... and the results passed as a regular metric of one of the above types, using milliseconds as the unit and also accompanied by a code location (as an attribute).

Sending Metrics to Sentry

A custom exporter can be created to extend OpenTelemetry dotnet.

[bruno-garcia]

Useful to send as default metrics: https://learn.microsoft.com/en-us/dotnet/api/system.threading.threadpool.getavailablethreads?view=net-8.0