Crosscompile python aarch64 wheels with dockcross (#25418)

* build aarch64 python wheels via crosscompilation

* yapf format code

* fix shellcheck complaints

* fix python37 aarch64 wheel build

* build python wheels on linux aarch64 with static libstdc++

* yapf format code

setup.py

@@ -138,6 +138,16 @@ BUILD_WITH_SYSTEM_CARES = os.environ.get('GRPC_PYTHON_BUILD_SYSTEM_CARES',
 # runtime, the shared library must be installed
 BUILD_WITH_SYSTEM_RE2 = os.environ.get('GRPC_PYTHON_BUILD_SYSTEM_RE2', False)
 
+# Export this variable to force building the python extension with a statically linked libstdc++.
+# At least on linux, this is normally not needed as we can build manylinux-compatible wheels on linux just fine
+# without statically linking libstdc++ (which leads to a slight increase in the wheel size).
+# This option is useful when crosscompiling wheels for aarch64 where
+# it's difficult to ensure that the crosscompilation toolchain has a high-enough version
+# of GCC (we require >4.9) but still uses old-enough libstdc++ symbols.
+# TODO(jtattermusch): remove this workaround once issues with crosscompiler version are resolved.
+BUILD_WITH_STATIC_LIBSTDCXX = os.environ.get(
+    'GRPC_PYTHON_BUILD_WITH_STATIC_LIBSTDCXX', False)
+
 # For local development use only: This skips building gRPC Core and its
 # dependencies, including protobuf and boringssl. This allows "incremental"
 # compilation by first building gRPC Core using make, then building only the
@@ -239,6 +249,9 @@ if EXTRA_ENV_LINK_ARGS is None:
 EXTRA_COMPILE_ARGS = shlex.split(EXTRA_ENV_COMPILE_ARGS)
 EXTRA_LINK_ARGS = shlex.split(EXTRA_ENV_LINK_ARGS)
 
+if BUILD_WITH_STATIC_LIBSTDCXX:
+    EXTRA_LINK_ARGS.append('-static-libstdc++')
+
 CYTHON_EXTENSION_PACKAGE_NAMES = ()
 
 CYTHON_EXTENSION_MODULE_NAMES = ('grpc._cython.cygrpc',)

src/python/grpcio/commands.py

@@ -24,6 +24,7 @@ import re
 import shutil
 import subprocess
 import sys
+import sysconfig
 import traceback
 
 import setuptools
@@ -211,6 +212,20 @@ class BuildExt(build_ext.build_ext):
     }
     LINK_OPTIONS = {}
 
+    def get_ext_filename(self, ext_name):
+        # since python3.5, python extensions' shared libraries use a suffix that corresponds to the value
+        # of sysconfig.get_config_var('EXT_SUFFIX') and contains info about the architecture the library targets.
+        # E.g. on x64 linux the suffix is ".cpython-XYZ-x86_64-linux-gnu.so"
+        # When crosscompiling python wheels, we need to be able to override this suffix
+        # so that the resulting file name matches the target architecture and we end up with a well-formed
+        # wheel.
+        filename = build_ext.build_ext.get_ext_filename(self, ext_name)
+        orig_ext_suffix = sysconfig.get_config_var('EXT_SUFFIX')
+        new_ext_suffix = os.getenv('GRPC_PYTHON_OVERRIDE_EXT_SUFFIX')
+        if new_ext_suffix and filename.endswith(orig_ext_suffix):
+            filename = filename[:-len(orig_ext_suffix)] + new_ext_suffix
+        return filename
+
     def build_extensions(self):
 
         def compiler_ok_with_extra_std():

tools/distrib/python/grpcio_tools/setup.py

@@ -71,6 +71,16 @@ PY3 = sys.version_info.major == 3
 # to have been generated by building first *with* Cython support.
 BUILD_WITH_CYTHON = os.environ.get('GRPC_PYTHON_BUILD_WITH_CYTHON', False)
 
+# Export this variable to force building the python extension with a statically linked libstdc++.
+# At least on linux, this is normally not needed as we can build manylinux-compatible wheels on linux just fine
+# without statically linking libstdc++ (which leads to a slight increase in the wheel size).
+# This option is useful when crosscompiling wheels for aarch64 where
+# it's difficult to ensure that the crosscompilation toolchain has a high-enough version
+# of GCC (we require >4.9) but still uses old-enough libstdc++ symbols.
+# TODO(jtattermusch): remove this workaround once issues with crosscompiler version are resolved.
+BUILD_WITH_STATIC_LIBSTDCXX = os.environ.get(
+    'GRPC_PYTHON_BUILD_WITH_STATIC_LIBSTDCXX', False)
+
 
 def check_linker_need_libatomic():
     """Test if linker on system needs libatomic."""
@@ -95,6 +105,24 @@ def check_linker_need_libatomic():
     return cpp_test.returncode == 0
 
 
+class BuildExt(build_ext.build_ext):
+    """Custom build_ext command."""
+
+    def get_ext_filename(self, ext_name):
+        # since python3.5, python extensions' shared libraries use a suffix that corresponds to the value
+        # of sysconfig.get_config_var('EXT_SUFFIX') and contains info about the architecture the library targets.
+        # E.g. on x64 linux the suffix is ".cpython-XYZ-x86_64-linux-gnu.so"
+        # When crosscompiling python wheels, we need to be able to override this suffix
+        # so that the resulting file name matches the target architecture and we end up with a well-formed
+        # wheel.
+        filename = build_ext.build_ext.get_ext_filename(self, ext_name)
+        orig_ext_suffix = sysconfig.get_config_var('EXT_SUFFIX')
+        new_ext_suffix = os.getenv('GRPC_PYTHON_OVERRIDE_EXT_SUFFIX')
+        if new_ext_suffix and filename.endswith(orig_ext_suffix):
+            filename = filename[:-len(orig_ext_suffix)] + new_ext_suffix
+        return filename
+
+
 # There are some situations (like on Windows) where CC, CFLAGS, and LDFLAGS are
 # entirely ignored/dropped/forgotten by distutils and its Cygwin/MinGW support.
 # We use these environment variables to thus get around that without locking
@@ -159,6 +187,9 @@ if EXTRA_ENV_LINK_ARGS is None:
 EXTRA_COMPILE_ARGS = shlex.split(EXTRA_ENV_COMPILE_ARGS)
 EXTRA_LINK_ARGS = shlex.split(EXTRA_ENV_LINK_ARGS)
 
+if BUILD_WITH_STATIC_LIBSTDCXX:
+    EXTRA_LINK_ARGS.append('-static-libstdc++')
+
 CC_FILES = [os.path.normpath(cc_file) for cc_file in protoc_lib_deps.CC_FILES]
 PROTO_FILES = [
     os.path.normpath(proto_file) for proto_file in protoc_lib_deps.PROTO_FILES
@@ -245,8 +276,7 @@ def extension_modules():
         return extensions
 
 
-setuptools.setup(
+setuptools.setup(name='grpcio-tools',
-    name='grpcio-tools',
                  version=grpc_version.VERSION,
                  description='Protobuf code generator for gRPC',
                  long_description=open(_README_PATH, 'r').read(),
@@ -263,4 +293,6 @@ setuptools.setup(
                      'setuptools',
                  ],
                  package_data=package_data(),
-)
+                 cmdclass={
+                     'build_ext': BuildExt,
+                 })

tools/dockerfile/grpc_artifact_python_manylinux2014_aarch64/Dockerfile

@@ -0,0 +1,31 @@
+# Copyright 2020 The gRPC Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# The aarch64 wheels are being crosscompiled to allow running the build
+# on x64 machine. The dockcross/manylinux2014-aarch64 image is a x86_64
+# image with crosscompilation toolchain installed.
+# Use an older version of dockcross image that has gcc4.9.4 because it was built
+# before https://github.com/dockcross/dockcross/pull/449
+FROM dockcross/manylinux2014-aarch64:20200929-608e6ac
+
+# Update the package manager
+RUN yum update -y && yum install -y curl-devel expat-devel gettext-devel openssl-devel zlib-devel
+
+###################################
+# Install Python build requirements
+RUN /opt/python/cp35-cp35m/bin/pip install --upgrade cython
+RUN /opt/python/cp36-cp36m/bin/pip install --upgrade cython
+RUN /opt/python/cp37-cp37m/bin/pip install --upgrade cython
+RUN /opt/python/cp38-cp38/bin/pip install --upgrade cython
+RUN /opt/python/cp39-cp39/bin/pip install --upgrade cython

tools/run_tests/artifacts/artifact_targets.py

@@ -144,8 +144,24 @@ class PythonArtifact:
             environ['PYTHON'] = '/opt/python/{}/bin/python'.format(
                 self.py_version)
             environ['PIP'] = '/opt/python/{}/bin/pip'.format(self.py_version)
+            if self.arch == 'aarch64':
+                environ['GRPC_SKIP_TWINE_CHECK'] = 'TRUE'
+                # when crosscompiling, we need to force statically linking libstdc++
+                # otherwise libstdc++ symbols would be too new and the resulting
+                # wheel wouldn't pass the auditwheel check.
+                # This is needed because C core won't build with GCC 4.8 that's
+                # included in the default dockcross toolchain and we needed
+                # to opt into using a slighly newer version of GCC.
+                environ['GRPC_PYTHON_BUILD_WITH_STATIC_LIBSTDCXX'] = 'TRUE'
+
+            else:
+                # only run auditwheel if we're not crosscompiling
+                environ['GRPC_RUN_AUDITWHEEL_REPAIR'] = 'TRUE'
+                # only build the packages that depend on grpcio-tools
+                # if we're not crosscompiling.
+                # - they require protoc to run on current architecture
+                # - they only have sdist packages anyway, so it's useless to build them again
                 environ['GRPC_BUILD_GRPCIO_TOOLS_DEPENDENTS'] = 'TRUE'
-            environ['GRPC_BUILD_MANYLINUX_WHEEL'] = 'TRUE'
             return create_docker_jobspec(
                 self.name,
                 # NOTE(rbellevi): Do *not* update this without also ensuring the
@@ -375,6 +391,9 @@ def targets():
         PythonArtifact('manylinux2010', 'x86', 'cp37-cp37m'),
         PythonArtifact('manylinux2010', 'x86', 'cp38-cp38'),
         PythonArtifact('manylinux2010', 'x86', 'cp39-cp39'),
+        PythonArtifact('manylinux2014', 'aarch64', 'cp37-cp37m'),
+        PythonArtifact('manylinux2014', 'aarch64', 'cp38-cp38'),
+        PythonArtifact('manylinux2014', 'aarch64', 'cp39-cp39'),
         PythonArtifact('linux_extra', 'armv7', '2.7'),
         PythonArtifact('linux_extra', 'armv7', '3.5'),
         PythonArtifact('linux_extra', 'armv7', '3.6'),

tools/run_tests/artifacts/build_artifact_python.sh

@@ -33,6 +33,24 @@ export GRPC_PYTHON_BUILD_EXT_COMPILER_JOBS=${GRPC_PYTHON_BUILD_EXT_COMPILER_JOBS
 mkdir -p "${ARTIFACTS_OUT}"
 ARTIFACT_DIR="$PWD/${ARTIFACTS_OUT}"
 
+# check whether we are crosscompiling. AUDITWHEEL_ARCH is set by the dockcross docker image.
+if [ "$AUDITWHEEL_ARCH" == "aarch64" ]
+then
+  # when crosscompiling for aarch64, --plat-name needs to be set explicitly
+  # to end up with correctly named wheel file
+  # the value should be manylinuxABC_ARCH and dockcross docker image
+  # conveniently provides the value in the AUDITWHEEL_PLAT env
+  WHEEL_PLAT_NAME_FLAG="--plat-name=$AUDITWHEEL_PLAT"
+
+  # override the value of EXT_SUFFIX to make sure the crosscompiled .so files in the wheel have the correct filename suffix
+  GRPC_PYTHON_OVERRIDE_EXT_SUFFIX="$(${PYTHON} -c 'import sysconfig; print(sysconfig.get_config_var("EXT_SUFFIX").replace("-x86_64-linux-gnu.so", "-aarch64-linux-gnu.so"))')"
+  export GRPC_PYTHON_OVERRIDE_EXT_SUFFIX
+
+  # Set to empty string to disable the option (see https://github.com/grpc/grpc/issues/24498)
+  # TODO: enable ASM optimizations for crosscompiled wheels
+  export GRPC_BUILD_WITH_BORING_SSL_ASM=""
+fi
+
 # Build the source distribution first because MANIFEST.in cannot override
 # exclusion of built shared objects among package resources (for some
 # inexplicable reason).
@@ -40,7 +58,8 @@ ${SETARCH_CMD} "${PYTHON}" setup.py sdist
 
 # Wheel has a bug where directories don't get excluded.
 # https://bitbucket.org/pypa/wheel/issues/99/cannot-exclude-directory
-${SETARCH_CMD} "${PYTHON}" setup.py bdist_wheel
+# shellcheck disable=SC2086
+${SETARCH_CMD} "${PYTHON}" setup.py bdist_wheel $WHEEL_PLAT_NAME_FLAG
 
 GRPCIO_STRIP_TEMPDIR=$(mktemp -d)
 GRPCIO_TAR_GZ_LIST=( dist/grpcio-*.tar.gz )
@@ -78,9 +97,10 @@ mv "${GRPCIO_STRIPPED_TAR_GZ}" "${GRPCIO_TAR_GZ}"
 ${SETARCH_CMD} "${PYTHON}" tools/distrib/python/grpcio_tools/setup.py sdist
 
 # Build gRPC tools package binary distribution
-${SETARCH_CMD} "${PYTHON}" tools/distrib/python/grpcio_tools/setup.py bdist_wheel
+# shellcheck disable=SC2086
+${SETARCH_CMD} "${PYTHON}" tools/distrib/python/grpcio_tools/setup.py bdist_wheel $WHEEL_PLAT_NAME_FLAG
 
-if [ "$GRPC_BUILD_MANYLINUX_WHEEL" != "" ]
+if [ "$GRPC_RUN_AUDITWHEEL_REPAIR" != "" ]
 then
   for wheel in dist/*.whl; do
     "${AUDITWHEEL}" show "$wheel" | tee /dev/stderr |  grep -E -w "$AUDITWHEEL_PLAT"
@@ -136,12 +156,15 @@ then
   cp -r src/python/grpcio_status/dist/* "$ARTIFACT_DIR"
 fi
 
+if [ "$GRPC_SKIP_TWINE_CHECK" == "" ]
+then
   # Ensure the generated artifacts are valid.
   "${PYTHON}" -m pip install virtualenv
   "${PYTHON}" -m virtualenv venv || { "${PYTHON}" -m pip install virtualenv==16.7.9 && "${PYTHON}" -m virtualenv venv; }
   venv/bin/python -m pip install "twine<=2.0"
   venv/bin/python -m twine check dist/* tools/distrib/python/grpcio_tools/dist/*
   rm -rf venv/
+fi
 
 cp -r dist/* "$ARTIFACT_DIR"
 cp -r tools/distrib/python/grpcio_tools/dist/* "$ARTIFACT_DIR"