Does otel-cpp require protobuf v3 to build?

[dluongiop]

Hi,

I'm trying to build otel-cpp in Amazon Linux2. I get the following errors when configured with -DWITH_OTLP=ON -DWITH_OTLP_HTTP=ON

[ec2-user@al2testing build]$ cmake3 .. -DBUILD_TESTING=OFF -DWITH_EXAMPLES=OFF -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DBUILD_SHARED_LIBS=ON -DWITH_OTLP=ON -DWITH_OTLP_HTTP=ON -DWITH_OTLP_GRPC=OFF
-- The C compiler identification is GNU 7.3.1
-- The CXX compiler identification is GNU 7.3.1
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc - works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ - works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Building for architecture ARCH=x64
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
-- Found Protobuf: /usr/lib64/libprotobuf.so;-lpthread (found version "2.5.0")
-- PROTOBUF_PROTOC_EXECUTABLE=/usr/bin/protoc
-- opentelemetry-proto dependency satisfied by: git submodule
-- Performing Test check_cxx_compiler_flag_-Wno-type-limits
-- Performing Test check_cxx_compiler_flag_-Wno-type-limits - Success
-- Performing Test check_cxx_compiler_flag_-Wno-deprecated-declarations
-- Performing Test check_cxx_compiler_flag_-Wno-deprecated-declarations - Success
-- Performing Test check_cxx_compiler_flag_-Wno-unused-parameter
-- Performing Test check_cxx_compiler_flag_-Wno-unused-parameter - Success
-- Found CURL: /usr/lib64/libcurl.so (found version "7.88.1")
-- Found CURL: /usr/lib64/libcurl.so, version
-- nlohmann::json dependency satisfied by: package
Building with nostd types...
-- Configuring done
-- Generating done
-- Build files have been written to: /home/ec2-user/otel/opentelemetry-cpp-1.8.3/build
[ec2-user@al2testing build]$ make
[  1%] Generating generated/third_party/opentelemetry-proto/opentelemetry/proto/common/v1/common.pb.h, generated/third_party/opentelemetry-proto/opentelemetry/proto/common/v1/common.pb.cc, generated/third_party/opentelemetry-proto/opentelemetry/proto/resource/v1/resource.pb.h, generated/third_party/opentelemetry-proto/opentelemetry/proto/resource/v1/resource.pb.cc, generated/third_party/opentelemetry-proto/opentelemetry/proto/trace/v1/trace.pb.h, generated/third_party/opentelemetry-proto/opentelemetry/proto/trace/v1/trace.pb.cc, generated/third_party/opentelemetry-proto/opentelemetry/proto/logs/v1/logs.pb.h, generated/third_party/opentelemetry-proto/opentelemetry/proto/logs/v1/logs.pb.cc, generated/third_party/opentelemetry-proto/opentelemetry/proto/metrics/v1/metrics.pb.h, generated/third_party/opentelemetry-proto/opentelemetry/proto/metrics/v1/metrics.pb.cc, generated/third_party/opentelemetry-proto/opentelemetry/proto/collector/trace/v1/trace_service.pb.h, generated/third_party/opentelemetry-proto/opentelemetry/proto/collector/trace/v1/trace_service.pb.cc, generated/third_party/opentelemetry-proto/opentelemetry/proto/collector/logs/v1/logs_service.pb.h, generated/third_party/opentelemetry-proto/opentelemetry/proto/collector/logs/v1/logs_service.pb.cc, generated/third_party/opentelemetry-proto/opentelemetry/proto/collector/metrics/v1/metrics_service.pb.h, generated/third_party/opentelemetry-proto/opentelemetry/proto/collector/metrics/v1/metrics_service.pb.cc
Missing value for flag: --experimental_allow_proto3_optional
make[2]: *** [generated/third_party/opentelemetry-proto/opentelemetry/proto/common/v1/common.pb.h] Error 1
make[1]: *** [CMakeFiles/opentelemetry_proto.dir/all] Error 2
make: *** [all] Error 2
[ec2-user@al2testing build]$

[owent]

Yes, it requires protobuf 3.13.0 or upper.

[Falmarri]

@dluongiop you can hack around it like this:

    && sed -i 's/"--experimental_allow_proto3_optional"//g' ../cmake/opentelemetry-proto.cmake \
    && sed -i 's/message.ByteSizeLong()/message.ByteSize()/g' ../exporters/otlp/src/otlp_http_client.cc \
    && sed -i 's;#  include "google/protobuf/stubs/port.h";#  include "google/protobuf/stubs/port.h"\n#  include <iostream>\n;g' ../exporters/otlp/src/otlp_http_client.cc \
    && sed -i 's;PRIVATE CURL::libcurl;PRIVATE /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4;g' ../ext/src/http/client/curl/CMakeLists.txt \
    && sed -i '1i#include <iostream>' ../exporters/otlp/src/otlp_http_client.cc 

We only use this for traces, not spans, so can't say for sure what all this breaks. But it at least works for sending traces via the protobuf protocol

[owent]

@dluongiop you can hack around it like this:

    && sed -i 's/"--experimental_allow_proto3_optional"//g' ../cmake/opentelemetry-proto.cmake \
    && sed -i 's/message.ByteSizeLong()/message.ByteSize()/g' ../exporters/otlp/src/otlp_http_client.cc \
    && sed -i 's;#  include "google/protobuf/stubs/port.h";#  include "google/protobuf/stubs/port.h"\n#  include <iostream>\n;g' ../exporters/otlp/src/otlp_http_client.cc \
    && sed -i 's;PRIVATE CURL::libcurl;PRIVATE /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4;g' ../ext/src/http/client/curl/CMakeLists.txt \
    && sed -i '1i#include <iostream>' ../exporters/otlp/src/otlp_http_client.cc 

We only use this for traces, not spans, so can't say for sure what all this breaks. But it at least works for sending traces via the protobuf protocol

Protobuf v3 also has different default pack settings for repeated numeric types. Which also take effect on compatibility of packed binary.