Support for fastify

[PatrickHeneise]

Is your plugin request related to a problem? Please describe.

We'd like to use the gcloud trace agent in our software which is runs on fastify. Fastify uses a similar API to express, I was hoping this would work out of the box, but unfortunately that's not the case.

Is it applicable for Node or Browser or both

• Node

Additional context

Original issue: googleapis/cloud-trace-nodejs#1167 (comment)

[mayurkale22]

Thanks for opening this. I marked it as up-for-grabs for now. If you are feeling motivated, maybe you can attempt to write solution and open a PR.

[carolinee21]

@PatrickHeneise Hi - I was wondering if there have been any updates on this. Thanks!

[PatrickHeneise]

Haven't had a chance yet. @mayurkale22 how would I start on this? And, if I add fastify, how does it make it's way into Google Trace?

[dyladan]

@PatrickHeneise I would take a look at some of the node plugins in this repo to get an idea how they work, but generally we use shimmer to wrap functions exported by the module we want to instrument. The plugin uses the SDK to generate spans and other instrumentation data, and the SDK handles exporting it to a backend using the configured tracing exporter. Google cloud trace has a tracing exporter that you would use for that.

[vmarchaud]

For the plugin, you could refer to the implementation done by datadog here: https://github.com/DataDog/dd-trace-js/tree/master/packages/datadog-plugin-fastify/src
Note that the Tracer API is way different but at least you know which functions to patch :)

[adamegyed]

It looks like someone has already written a library connecting fastify to OpenTelemetry here: https://github.com/mkinoshi/fastify-opentelemetry
However, this does not conform to the spec of an OpenTelemetry plugin, rather, it is a fastify plugin that interacts with OpenTelemetry. There might still be value in adapting this to the form of an OT plugin.

[dyladan]

Both approaches likely have value, but it may be better to spend time elsewhere if there is already a good way to get spans from fastify.

[HW13]

We recently published a fastify plugin that utilizes @opentelemetry/api to trace requests. It's lightweight, but provides the tools to add more granular/custom tracing implementations if desired. Cheers 😄 -> https://github.com/autotelic/fastify-opentelemetry

[dyladan]

@HW13 You may want to think about listing it on the registry

[HW13]

Thanks for the suggestion @dyladan 😎 - just opened a PR -> open-telemetry/opentelemetry.io#241

[vmarchaud]

@dyladan Do we want to keep this issue open since there are multiple solutions available ?

[rauno56]

Support for fastify is in the contrib now in addition to the one mentioned above: https://github.com/autotelic/fastify-opentelemetry