Import error trying to run gRPC on alpine

[bbassingthwaite]

Hi, I am trying to run a gRPC server inside of a docker container and I am receiving the error:

Traceback (most recent call last):
  File "main.py", line 34, in <module>
    import pt_pb2
  File "/etc/app/pt_pb2.py", line 179, in <module>
    from grpc.beta import implementations as beta_implementations
  File "/usr/lib/python2.7/site-packages/grpc/beta/implementations.py", line 38, in <module>
    from grpc._adapter import _intermediary_low
  File "/usr/lib/python2.7/site-packages/grpc/_adapter/_intermediary_low.py", line 57, in <module>
    from grpc._adapter import _low
  File "/usr/lib/python2.7/site-packages/grpc/_adapter/_low.py", line 33, in <module>
    from grpc._cython import cygrpc
ImportError: Error loading shared library ld-linux-x86-64.so.2: No such file or directory (needed by /usr/lib/python2.7/site-packages/grpc/_cython/cygrpc.so)

My docker file is:

FROM gliderlabs/alpine:3.3

RUN apk add --update \
    python \
    python-dev \
    py-pip \
    build-base \
    libffi-dev \
    openssl-dev \
    curl \
  && pip install virtualenv \
  && rm -rf /var/cache/apk/*

RUN mkdir /etc/app/
COPY ./app/ /etc/app/
RUN pip install gcloud grpcio
WORKDIR /etc/app/
EXPOSE 80
CMD ["python", "main.py"]

I am installing gRPC from PYPI and would not expect any other dependencies?

Thanks,
Braden

[deedubs]

@bbassingthwaite-va Have you tried installing libc6-compat

REF: https://pkgs.alpinelinux.org/contents?file=ld-linux-x86-64.so.2&path=&name=&branch=&repo=&arch=

[samkelleher]

Adding a comment as found this error via Google and the solution worked for me. Had the same error, slightly different trace - but ultimately resolved by installing the libc6-compat package.

My tracelog for reference:

module.js:440
  return process.dlopen(module, path._makeLong(filename));
                 ^
Error: Error loading shared library ld-linux-x86-64.so.2: No such file or directory (needed by /usr/src/app/node_modules/grpc/src/node/extension_binary/grpc_node.node)
    at Error (native)
    at Object.Module._extensions..node (module.js:440:18)
    at Module.load (module.js:357:32)
    at Function.Module._load (module.js:314:12)
    at Module.require (module.js:367:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (/usr/src/app/node_modules/grpc/src/node/src/grpc_extension.js:38:15)

[nathanielmanistaatgoogle]

Closing; the question here seems to be satisfactorily answered.

[rochdev]

I feel this has not in fact been satisfactorily answered. This should not be necessary if gRPC would have an official alpine build. The error on the npm module was also very confusing.

[deedubs]

I'll admit I scratched my head when I first encountered this but I don't put the onus on the gRPC team to create builds for every exotic libc implementation people can conjure up.

Alpine is very forthcoming with the use of musl libc. I think the onus is on us to understand what that means to the code we are trying to run.

In this case it means we need to install a compatibility shim libc6-compat.

Alpine has an excellent tool for getting to the bottom of these issues https://pkgs.alpinelinux.org/contents
(its actually how I initially resolved this issue myself)

For example you can find what, if any, packages may offer the missing ld-linux-x86-64.so.2 file we can use it like so https://pkgs.alpinelinux.org/contents?file=ld-linux-x86-64.so.2&path=&name=&branch=&repo=&arch=

[kpayson64]

Is the libc6-compat workaround still necessary?

I just spun up the alpine docker image we use for testing
https://github.com/grpc/grpc/blob/master/tools/dockerfile/test/cxx_alpine_x64/Dockerfile

I pip installed grpc, and was able to import grpc without running into the issue described above.

To make sure we didn't transitively pull in libc6-compat into our alpine docker image, I did
bash-4.3# apk info | grep libc6 and it came back empty.

[rochdev]

I agree in general that supporting other libc implementations is not necessarily a good idea, but in this case Alpine is quickly becoming the de facto Docker images base OS.

While I do agree that the fix is easy, understanding why it doesn't work can be painful as demonstrated by the quantity of issues related to Alpine in this repo (and any other large project that doesn't support musl).

Also note that I have no idea of the effort required to implement this directly in gRPC. I simply think it should at least be in the roadmap.

[rochdev]

@kpayson64 It is possible the entire glibc gets installed? Otherwise maybe an Alpine build does exist and is simply not being used by the npm module?

[kpayson64]

@rochdev
Can you confirm that you are still seeing this issue with the latest version of gRPC?

Alpine support was added this April, so probably wasn't there before gRPC 1.4.

[rochdev]

Indeed it seems that the @google-cloud/common-grpc npm module depends on ^1.3.1

https://github.com/GoogleCloudPlatform/google-cloud-node/blob/master/packages/common-grpc/package.json

I will open a PR there. Sorry for reviving this old thread!

[JustinBeckwith]

@murgatroid99 Why is this issue closed? This seems like something that should stay open until we make gRPC work out of the box on alpine.

[murgatroid99]

Well, it was originally closed because some solution had been provided. Now I believe it can stay closed because we have published precompiled binaries for alpine in gRPC 1.8.

[JustinBeckwith]

👏 this is awesome news! I didn't see that 1.8 went out!