How to support instrumentations for multiple major versions of libraries?

[ocelotl]

Issues like #1416 make me realize that we do not have a defined policy on how to deal with this kind of situation.

We could either:

1. Only support a particular version.
2. Try to support multiple versions by having a bunch of ifs and elses in the instrumentation code (like this).
3. Have $n$ opentelemetry-instrumentation-library-x, packages, where $x = 1 \dots n$ and $n$ is the number of major releases of library library (Github can render $math$! 😎).

All seem to have pros and cons, let us know what you think in the comments ✌️

P.S.:

This is somewhat related to a (horrible) solution I proposed before here.

[ocelotl]

1. Only support a particular version.

Easy for us, probably very bad for our users.

2. Try to support multiple versions by having a bunch of ifs and elses in the instrumentation code (like this).

Smells like trouble but it is at the same time the "nicest" one from a user perspective. If we follow this approach I would prefer that we don't have many ifs and elses spread around the instrumentation code but we have separate directories or modules for every major version and a general mechanism that "selects" the code to be used depending on the library version. This can lead to duplicated code, yes, but I would rather have that.

3. Have n opentelemetry-instrumentation-library-x, packages, where x=1…n and n is the number of major releases of library library (Github can render math! sunglasses).

Probably the better option considering that library2 and library3 can have conflicting dependencies? 🤷 Horrible still.