grpc: Unable to run grpcio wheel on alpine arvm7

What version of gRPC and what language are you using?

1.41.0 in python. Any grpcio release over 1.31.0 exhibits a variation on the problem.

What operating system (Linux, Windows,…) and version?

Linux arm32v7/alpine:3.12

What runtime / compiler are you using (e.g. python version or version of gcc)

Python 3.8.10 though other versions also show the same problem

What did you do?

Given an example Dockerfile like this:

FROM arm32v7/alpine:3.12

RUN apk add --no-cache python3 py3-pip
RUN apk add libstdc++ libc6-compat
RUN python3 --version

WORKDIR /code
COPY requirements.txt .
COPY example.py .

RUN pip3 install --no-cache-dir --only-binary=grpcio -r requirements.txt

CMD python3 ./example.py

Note that this also has problems finding the shared library without libstdc++ and libc6-compat but the errors has changed across grpc versions.

requirements.txt:

grpcio==1.41.0
google-cloud-pubsub

example.py

#!/usr/bin/python

from google.cloud import pubsub_v1

def main():
  print("Hello world")

if __name__ == "__main__":
  main()

Then run a build like this:

$ docker build --tag grpcio-armv7 .

What did you expect to see?

$ docker run grpcio-armv7
Hello world

Note, that this is what I see for alpine images on other architectures or different armv7 images like this:

FROM arm32v7/python:3.8-buster

What did you see instead?

$ docker run grpcio-armv7
Traceback (most recent call last):                                              
  File "./example.py", line 3, in <module>                                      
    from google.cloud import pubsub_v1                                          
  File "/usr/lib/python3.8/site-packages/google/cloud/pubsub_v1/__init__.py", li
ne 17, in <module>                                                              
    from google.cloud.pubsub_v1 import types                                    
  File "/usr/lib/python3.8/site-packages/google/cloud/pubsub_v1/types.py", line 
25, in <module>                                                                 
    from google.api_core import gapic_v1                                        
  File "/usr/lib/python3.8/site-packages/google/api_core/gapic_v1/__init__.py", 
line 16, in <module>                                                            
    from google.api_core.gapic_v1 import config                                 
  File "/usr/lib/python3.8/site-packages/google/api_core/gapic_v1/config.py", line 23, in <module>
    import grpc
  File "/usr/lib/python3.8/site-packages/grpc/__init__.py", line 22, in <module>
    from grpc import _compression
  File "/usr/lib/python3.8/site-packages/grpc/_compression.py", line 15, in <module>
    from grpc._cython import cygrpc
ImportError: Error relocating /usr/lib/python3.8/site-packages/grpc/_cython/cygrpc.cpython-38-arm-linux-gnueabihf.so: _ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE7reserveEv: symbol not found

When using an older version of grpcio such as 1.38.X, I see an error message like:

Traceback (most recent call last):
  File "./example.py", line 3, in <module>
    from google.cloud import pubsub_v1
  File "/usr/lib/python3.8/site-packages/google/cloud/pubsub_v1/__init__.py", line 17, in <module>
    from google.cloud.pubsub_v1 import types
  File "/usr/lib/python3.8/site-packages/google/cloud/pubsub_v1/types.py", line 25, in <module>
    from google.api_core import gapic_v1
  File "/usr/lib/python3.8/site-packages/google/api_core/gapic_v1/__init__.py", line 16, in <module>
    from google.api_core.gapic_v1 import config
  File "/usr/lib/python3.8/site-packages/google/api_core/gapic_v1/config.py", line 23, in <module>
    import grpc
  File "/usr/lib/python3.8/site-packages/grpc/__init__.py", line 23, in <module>
    from grpc._cython import cygrpc as _cygrpc
ImportError: Error relocating /usr/lib/python3.8/site-packages/grpc/_cython/cygrpc.cpython-38-arm-linux-gnueabihf.so: __strftime_l: symbol not found

This is similar to the first post of https://github.com/grpc/grpc/issues/24808 where the armv7 binary wheel has problems with alpine.

Anything else we should know about your project / environment?

This seems to have been an armv7 plus alpine issue that first happened last year. I have some history in https://github.com/home-assistant/core/issues/56669 though this was first seen with https://github.com/home-assistant/core/issues/40266 and https://github.com/home-assistant/core/issues/40148

Also note above that the Dockerfile explicitly adds libstdc++ libc6-compat which are not necessary for other platforms besides arvm7. Ideally that should not be needed and this could run on musl directly.

The discussion in https://github.com/grpc/grpc/issues/26620 seems quite relevant. Is building musllinux wheels for armv7 the right solution?