need some hints on building an app using cmake with otel

[Danl2620]

Apologies for the low information issue -- this should be a discord convo probably. I have a project that integrates otel and builds in bazel. I'm trying to build using cmake and get this compile error that is super confusing (regarding how/where Gauge is defined).

error: ‘Gauge’ is not a member of ‘opentelemetry::v1::metrics’

I just need a hint regard what might be happening -- thanks!

[lalitb]

You need to explicitly set OPENTELEMETRY_ABI_VERSION_NO macro to 2, to use Gauge.

[Danl2620]

Can you give me hint on how to do that (in CMake)? I'm not seeing any examples or docs.

Thanks!

[Danl2620]

I tried

target_compile_definitions(my-lib PRIVATE
    "OPENTELEMETRY_ABI_VERSION_NO=2")

But that created the compiler parameters " -DOPENTELEMETRY_ABI_VERSION_NO=1 -DOPENTELEMETRY_ABI_VERSION_NO=2" with the same result.

[lalitb]

Try setting the CMake variable WITH_ABI_VERSION_2 to ON in otel build.

[Danl2620]

Trying now. I was using the nix package directly from nixpkgs which doesn't incorporate that option. I'll do my own version of the package locally.

[Danl2620]

Ok, now with -DOPENTELEMETRY_ABI_VERSION_NO=2 on the compiler command linethe error has changed a little. Do I need to change the namesspacing?

 /build/source/src/metrics_provider/metrics_provider.hpp:229: error: 'Gauge' is not a member of 'opentelemetry::v2::metrics'

[lalitb]

This should have worked. This should work in general:

 $ cmake build -DWITH_ABI_VERSION_2=ON -DWITH_ABI_VERSION_1=OFF ..

Else, please share your build logs.