CMake configuration on Ubuntu 20.04 fails with v1.22.0

[markus456]

Describe your environment

Building in docker on ubuntu:20.04 (Image ID b7bab04fd9aa) with libraries from the operating system. CMake version appears to be 3.16 on Ubuntu 20.04 and since the main CMakeLists.txt has cmake_minimum_required(VERSION 3.14) this should still be fine.

Tested versions:

Version	Result
v1.20.0	OK
v1.21.0	OK
v1.22.0	ERROR
main	ERROR

The offending commit appears to be 3eec22c.

Steps to reproduce

Save the following script as testing-ubuntu.sh:

#!/bin/sh                                                                                                                                     
#                                                                                                                                             
# Usage: ./testing-ubuntu.sh GIT_TAG                                                                                                          
#                                                                                                                                             

git_tag=$1

export DEBIAN_FRONTEND=noninteractive
apt update
apt -y install git g++ protobuf-compiler libprotobuf-dev cmake libcurl4-openssl-dev

git clone -j 32 --recurse-submodules --shallow-submodules --depth=1 --branch=$git_tag https://github.com/open-telemetry/opentelemetry-cpp.git
mkdir /build && cd /build
cmake ../opentelemetry-cpp -DCMAKE_INSTALL_PREFIX=$PWD -DCMAKE_BUILD_TYPE=RelWithDebInfo -DWITH_ASYNC_EXPORT_PREVIEW=OFF -DCMAKE_POSITION_INDEPENDENT_CODE=Y -DBUILD_SHARED_LIBS=N -DWITH_ABI_VERSION_1=N -DWITH_ABI_VERSION_2=Y -DWITH_STL=CXX17 -DWITH_ABSEIL=N -DBUILD_TESTING=N -DWITH_BENCHMARK=N -DWITH_FUNC_TESTS=N -DWITH_EXAMPLES=N -DWITH_OTLP_GRPC=N -DWITH_OTLP_HTTP=Y -DWITH_OTLP_HTTP_COMPRESSION=N
make

Then run the following commands to reproduce the problem:

chmod +x testing-ubuntu.sh
docker run -d --rm --name=test-container ubuntu:20.04 sleep 11111
docker cp testing-ubuntu.sh test-container:/
docker exec -ti test-container /testing-ubuntu.sh v1.22.0

With version v1.22.0, the cmake step will fail with:

-- Using the single-header code from /opentelemetry-cpp/third_party/nlohmann-json/single_include/
CMake Error in third_party/nlohmann-json/CMakeLists.txt:
  INTERFACE_LIBRARY targets may only have whitelisted properties.  The
  property "CXX_INCLUDE_WHAT_YOU_USE" is not allowed.


CMake Error in third_party/nlohmann-json/CMakeLists.txt:
  INTERFACE_LIBRARY targets may only have whitelisted properties.  The
  property "CXX_CLANG_TIDY" is not allowed.

With version v1.21.0 and older, this issue does not appear. Reverting commit 3eec22c also fixes the problem.

None of these problems appear with Ubuntu 22.04 or newer.

What is the expected behavior?
I expected the configuration to complete without errors or to fail with an error reporting that this version of CMake is not supported.

What is the actual behavior?
CMake configuration fails as a result of passing incompatible properties.

Additional context

Additionally, even if the configuration step is fixed, it appears that the version of protoc is not new enough as the build fails with the following error:

[  0%] [Run]: "/usr/bin/protoc" "--proto_path=/opentelemetry-cpp/third_party/opentelemetry-proto" "--cpp_out=/build/generated/third_party/opentelemetry-proto" "--experimental_allow_proto3_optional" "/opentelemetry-cpp/third_party/opentelemetry-proto/opentelemetry/proto/common/v1/common.proto" "/opentelemetry-cpp/third_party/opentelemetry-proto/opentelemetry/proto/resource/v1/resource.proto" "/opentelemetry-cpp/third_party/opentelemetry-proto/opentelemetry/proto/trace/v1/trace.proto" "/opentelemetry-cpp/third_party/opentelemetry-proto/opentelemetry/proto/logs/v1/logs.proto" "/opentelemetry-cpp/third_party/opentelemetry-proto/opentelemetry/proto/metrics/v1/metrics.proto" "/opentelemetry-cpp/third_party/opentelemetry-proto/opentelemetry/proto/profiles/v1development/profiles.proto" "/opentelemetry-cpp/third_party/opentelemetry-proto/opentelemetry/proto/collector/trace/v1/trace_service.proto" "/opentelemetry-cpp/third_party/opentelemetry-proto/opentelemetry/proto/collector/logs/v1/logs_service.proto" "/opentelemetry-cpp/third_party/opentelemetry-proto/opentelemetry/proto/collector/metrics/v1/metrics_service.proto" "/opentelemetry-cpp/third_party/opentelemetry-proto/opentelemetry/proto/collector/profiles/v1development/profiles_service.proto"
Unknown flag: --experimental_allow_proto3_optional

I believe that there are implicit version dependencies on the tools that are used and there are missing version checks in the CMake files which fail to report them. I couldn't find any mention of required versions for the various components so I assume that it should work with what is in the OS repositories.

I'm attempting to find out what are the minimum supported versions of the various libraries that opentelemetry-cpp requires to successfully build to provide at least the HTTP protocol metrics exporting. I'm currently facing problems on Ubuntu 20.04 which, while in practice it's EOL since it's out of Maintenance & Security Support, is still claimed in main to be a "supported" platform (in the CI list) and thus I'd expect it to work. What I'm actually after is trying to get it to build on Rocky Linux 8 which also has an older version of protobuf in the OS repositories.

If there's a minimum version of protobuf that's required, which I believe there is as the comment next to the code that adds the --experimental_allow_proto3_optional flag says that it's added in version 3.13, documenting it in the dependencies and adding a check in CMake would be very much appreciated.

[dbarker]

Thanks for reporting this @markus456. The main INTERFACE_LIBRARY targets may only have whitelisted properties issue is valid. This can occur if using an older version of cmake and fetching dependencies. I'll address it in a new PR. The workaround is to either upgrade cmake or build/install the dependencies (see minimum tested below).

it appears that the version of protoc is not new enough

The protobuf-compiler libprotobuf-dev apt packages for 20.04 are quite old and below the minimum tested in CI.

I'm attempting to find out what are the minimum supported versions of the various libraries that opentelemetry-cpp requires to successfully build

We are testing with the minimum version tags of third-party dependencies in this file.
https://github.com/open-telemetry/opentelemetry-cpp/blob/main/install/cmake/third_party_minimum

[markus456]

I filed a pull request that documents the minimum required versions of the libraries. Hopefully this'll help others to build it on systems with older versions of the libraries in question.

As for the CMake problem, I think that unless it's intentional that CMake 3.14 is supported, incrementing the required version would be the simplest way to avoid problems like these. CMake 3.14 is quite old and it's missing a lot of useful functionality added in later versions which (IMO) makes it that much harder to maintain things.

[dbarker]

I filed a pull request that documents the minimum required versions of the libraries. Hopefully this'll help others to build it on systems with older versions of the libraries in question.

Thanks!

As for the CMake problem, I think that unless it's intentional that CMake 3.14 is supported, incrementing the required version would be the simplest way to avoid problems like these.

It is intentional to support CMake 3.14 at this point (please see #3348 and the linked PR). It seems reasonable to work towards tracking the CMake minimum version used by opentelemetry-cpp dependencies (googletest, grpc, protobuf, ..). Those dependencies follow the Google policy for upgrading CMake (https://opensource.google/documentation/policies/cplusplus-support#build_systems).