support: use cgo to generate Go constants from eBPF

[florianl]

Pragmatic approach to get rid of some CGO parts.

Creating just a draft atm to figure out details and more testing.

Fixes #331

[dmathieu]

Probably for another PR, but shouldn't we have a CI check that runs make generate and verifies the GIT repository remains clean (to ensure the generated code is always up do date)?

[rockdaboot]

nit: Use a exit function for the cleanup like

function cleanup {
  # Clean up temporary files
  rm -rf _obj/ types_gen.go
}
trap cleanup EXIT

[florianl]

Replacing a single line instruction with a multiple line alternative feels not right. Such clean up functions make sense, if they are more complex. But I don't see the need for this case.

[rockdaboot]

I just ended up too often after a failure or a ctrl-c with temporary files on my disk. It is a bit annoying and costs my time. A proper cleanup is good engineering practice.

[christos68k]

If the intermediate files are not useful for debugging failures (and they don't seem to be) let's add cleanup here like @rockdaboot suggests. The other option would be to add them to make clean.

EDIT: Actually maybe make clean is better as the intermediate files being present can speed up debugging a failure and updating support/types.go.

[rockdaboot]

Just out of interest, how often are you going to debug the constants so that it is worth it to always keep intermediate files? (My gut feeling says never)

[florianl]

Probably for another PR, but shouldn't we have a CI check that runs make generate and verifies the GIT repository remains clean (to ensure the generated code is always up do date)?

This exists already. The Makefile target generate is executed as dependency of make test:

opentelemetry-ebpf-profiler/.github/workflows/unit-test-on-pull-request.yml

Line 73 in 3c188fa

run: make test TARGET_ARCH=${{ matrix.target_arch }}

[dmathieu]

Ah, sorry, I looked for make generate and missed that.

[rockdaboot]

Too bad that there is the -m64 when cross-compiling, so that this shell script is required 😞

[christos68k]

If the intermediate files are not useful for debugging failures (and they don't seem to be) let's add cleanup here like @rockdaboot suggests. The other option would be to add them to make clean.

EDIT: Actually maybe make clean is better as the intermediate files being present can speed up debugging a failure and updating support/types.go.