Add google-protobuf and grpc to your Gemfile and specify the platform. The bundle install command will compile the gems
for the gems from source.

gem "google-protobuf", platforms: ["ruby"]
gem "grpc", "~> 1.22", platforms: ["ruby"]

Install libc6-compat

RUN apk add --update libc6-compat

Create a symbolic link

RUN ln -s /lib64/ld-linux-x86-64.so.2 /lib/ld-linux-x86-64.so.2

RUN CFLAGS="-Wno-cast-function-type" BUNDLE_FORCE_RUBY_PLATFORM=1 bundle install

BUNDLE_FORCE_RUBY_PLATFORM=1: Ignore the current machine's platform and install only ruby platform gems.
As a result, gems with native extensions will be compiled from source.