Support qemu in GitHub Actions

.github/workflows/test.yml

@@ -24,7 +24,8 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-18.04, windows-latest, macos-latest]
+        os: [ubuntu-18.04]
+        # os: [ubuntu-18.04, windows-latest, macos-latest]
         python_version: ['3.7']
     timeout-minutes: 180
     steps:
@@ -47,6 +48,13 @@ jobs:
       id: pr-labels
       uses: joerick/pr-labels-action@v1.0.6
 
+    - name: Set up QEMU
+      id: qemu
+      uses: docker/setup-qemu-action@v1
+      with:
+        platforms: all
+      if: runner.os == 'Linux'
+
     - name: Sample build
       if: contains(steps.pr-labels.outputs.labels, ' ci-sample-build ')
       run: |

cibuildwheel/__main__.py

@@ -17,6 +17,7 @@
     parse_environment,
 )
 from cibuildwheel.util import (
+    Architecture,
     BuildOptions,
     BuildSelector,
     DependencyConstraints,
@@ -67,6 +68,22 @@ def main() -> None:
                             run in Windows, and it will build and test for all versions of
                             Python. Default: auto.
                         ''')
+
+    parser.add_argument(
+        '-a',
+        '--architectures',
+        choices=[arch.value for arch in Architecture],
+        default=[],
+        help='''
+            Comma-separated list of CPU architectures to build for.
+            If unspecified, builds the architectures natively supported
+            on this machine. Set this option to build an architecture
+            via emulation, for example, using binfmt_misc and qemu.
+        ''',
+        action="extend",
+        nargs="+",
+        type=Architecture,
+    )
     parser.add_argument('--output-dir',
                         default=os.environ.get('CIBW_OUTPUT_DIR', 'wheelhouse'),
                         help='Destination folder for the wheels.')
@@ -169,7 +186,7 @@ def main() -> None:
         exit(2)
 
     if args.print_build_identifiers:
-        print_build_identifiers(platform, build_selector)
+        print_build_identifiers(platform, build_selector, args.architectures)
         exit(0)
 
     manylinux_images: Optional[Dict[str, str]] = None
@@ -202,6 +219,7 @@ def main() -> None:
             manylinux_images[build_platform] = image
 
     build_options = BuildOptions(
+        architectures=args.architectures,
         package_dir=package_dir,
         output_dir=output_dir,
         test_command=test_command,
@@ -284,10 +302,12 @@ def print_preamble(platform: str, build_options: BuildOptions) -> None:
     print('\nHere we go!\n')
 
 
-def print_build_identifiers(platform: str, build_selector: BuildSelector) -> None:
+def print_build_identifiers(
+    platform: str, build_selector: BuildSelector, architectures: List[Architecture]
+) -> None:
     python_configurations: List[Any] = []
     if platform == 'linux':
-        python_configurations = cibuildwheel.linux.get_python_configurations(build_selector)
+        python_configurations = cibuildwheel.linux.get_python_configurations(build_selector, architectures)
     elif platform == 'windows':
         python_configurations = cibuildwheel.windows.get_python_configurations(build_selector)
     elif platform == 'macos':

cibuildwheel/linux.py

@@ -1,4 +1,5 @@
 import platform
+import re
 import subprocess
 import sys
 import textwrap
@@ -8,29 +9,19 @@
 
 from .docker_container import DockerContainer
 from .logger import log
-from .util import (BuildOptions, BuildSelector, NonPlatformWheelError,
-                   get_build_verbosity_extra_flags, prepare_command)
-
-
-def matches_platform(identifier: str) -> bool:
-    pm = platform.machine()
-    if pm == "x86_64":
-        # x86_64 machines can run i686 docker containers
-        if identifier.endswith('x86_64') or identifier.endswith('i686'):
-            return True
-    elif pm == "i686":
-        if identifier.endswith('i686'):
-            return True
-    elif pm == "aarch64":
-        if identifier.endswith('aarch64'):
-            return True
-    elif pm == "ppc64le":
-        if identifier.endswith('ppc64le'):
-            return True
-    elif pm == "s390x":
-        if identifier.endswith('s390x'):
-            return True
-    return False
+from .util import (
+    Architecture, BuildOptions, BuildSelector, NonPlatformWheelError,
+    get_build_verbosity_extra_flags, prepare_command,
+)
+
+
+re_pattern = re.compile(r'[cp]p\d{2}-manylinux_(\w*)')
+
+
+def matches_platform(identifier: str, supported_platforms: List[Architecture]) -> bool:
+    matched_architecture = re_pattern.search(identifier)
+    id_architecture = matched_architecture.group(1) if matched_architecture else ''
+    return id_architecture in supported_platforms
 
 
 class PythonConfiguration(NamedTuple):
@@ -43,7 +34,9 @@ def path(self):
         return PurePath(self.path_str)
 
 
-def get_python_configurations(build_selector: BuildSelector) -> List[PythonConfiguration]:
+def get_python_configurations(
+    build_selector: BuildSelector, architectures: List[Architecture]
+) -> List[PythonConfiguration]:
     python_configurations = [
         PythonConfiguration(version='2.7', identifier='cp27-manylinux_x86_64', path_str='/opt/python/cp27-cp27m'),
         PythonConfiguration(version='2.7', identifier='cp27-manylinux_x86_64', path_str='/opt/python/cp27-cp27mu'),
@@ -78,8 +71,18 @@ def get_python_configurations(build_selector: BuildSelector) -> List[PythonConfi
         PythonConfiguration(version='3.8', identifier='cp38-manylinux_s390x', path_str='/opt/python/cp38-cp38'),
         PythonConfiguration(version='3.9', identifier='cp39-manylinux_s390x', path_str='/opt/python/cp39-cp39'),
     ]
+
     # skip builds as required
-    return [c for c in python_configurations if matches_platform(c.identifier) and build_selector(c.identifier)]
+    target_archs = architectures or [Architecture(platform.machine())]
+    # x86_64 machines can run i686 docker containers
+    if Architecture.i686 not in target_archs and Architecture.x86_64 in target_archs:
+        target_archs.append(Architecture.i686)
+    print("matching platforms to architectures: ", target_archs)
+    return [
+        c for c in python_configurations
+        if matches_platform(c.identifier, target_archs)
+        and build_selector(c.identifier)
+    ]
 
 
 def build(options: BuildOptions) -> None:
@@ -93,7 +96,7 @@ def build(options: BuildOptions) -> None:
         exit(2)
 
     assert options.manylinux_images is not None
-    python_configurations = get_python_configurations(options.build_selector)
+    python_configurations = get_python_configurations(options.build_selector, options.architectures)
     platforms = [
         ('cp', 'manylinux_x86_64', options.manylinux_images['x86_64']),
         ('cp', 'manylinux_i686', options.manylinux_images['i686']),

cibuildwheel/util.py

@@ -121,7 +121,16 @@ def __repr__(self):
         return f'{self.__class__.__name__}{self.base_file_path!r})'
 
 
+class Architecture(str, Enum):
+    x86_64 = 'x86_64'
+    i686 = 'i686'
+    aarch64 = 'aarch64'
+    ppc64le = 'ppc64le'
+    s390x = 's390x'
+
+
 class BuildOptions(NamedTuple):
+    architectures: List[Architecture]
     package_dir: Path
     output_dir: Path
     build_selector: BuildSelector