Difference between plugin and instrumentation

[morigs]

Hi. I couldn't find any docs which could clarify difference between instrumentation and plugin.
For example what's the difference between these two:

• https://github.com/open-telemetry/opentelemetry-js/tree/main/packages/opentelemetry-instrumentation-http
• https://github.com/open-telemetry/opentelemetry-js/tree/main/packages/opentelemetry-plugin-http

Which rule should contributors use when choosing name for a new integration?
For example express and koa are both http frameworks. But koa integration uses instrumentation term and express integration - plugin.

[vmarchaud]

Plugin was the original system (pretty much ported from opencensus) in which we implement support for auto-instrumentation, however it has several drawbacks:

• Auto-instrumentation doesn't work when using Yarn 2 with PnP #1412
• node-fetch module cannot be auto-instrumented #1315
• Only support for traces and our end goal would be to have a single auto instrumentation that generate both traces and metrics.
• Being able to auto instrument multiples packages at once, this makes sense for @opentelemetry/instrumentation-http that both handle http and https or @opentelemetry/instrumentation-grpc that handle grpc and @grpc/grpc-js, that allows to keep related utils where we use them
• Allows auto instrumentation to only depend on @opentelemetry/api so they works with any SDK (and not necessarily only the sdk we provide)
• Not tech stuff but at the time the name instrumentation was decided at the spec level to represent all auto instrumentations packages so we neeed to rename all of the plugins that already exists.

So we started to migrate all of them to the new @opentelemetry/instrumentation package that fixes all of the above, we are almost done (only few of contrib one are left). We will likely finish this migration, deprecate all the of plugin and start using all instrumentation by default.

PS: koa and hapi have both instrumentation in their name but are actually based on the old plugin system, so we'll to migrate them too.

[morigs]

Thanks for clear answer!
Kinda separate but related question: isn't this outdated? Shall I create an issue to update this doc?

[vmarchaud]

Yeah i think this is outdated, most of the documents in this folder are aswell i believe