Allow architecture selection

cibuildwheel/__main__.py

@@ -17,6 +17,7 @@ from cibuildwheel.environment import (
     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

@@ -9,18 +9,18 @@ from typing import List, NamedTuple, Union
 
 from .docker_container import DockerContainer
 from .logger import log
-from .util import (BuildOptions, BuildSelector, NonPlatformWheelError,
-                   get_build_verbosity_extra_flags, prepare_command)
+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[str]) -> bool:
+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 ''
-    # x86_64 machines can run i686 docker containers
-    id_architecture = id_architecture if id_architecture == 'i686' else 'x86_64'
     return id_architecture in supported_platforms
 
 
@@ -34,7 +34,9 @@ class PythonConfiguration(NamedTuple):
         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'),
@@ -71,7 +73,11 @@ def get_python_configurations(build_selector: BuildSelector) -> List[PythonConfi
     ]
 
     # skip builds as required
-    target_archs = [platform.machine()]
+    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)
@@ -90,7 +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 @@ class DependencyConstraints:
         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