Merge pull request #482 from asfaltboy/support-quemu-on-github

Support qemu in GitHub Actions

.github/workflows/test.yml

@@ -24,7 +24,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-18.04, windows-latest, macos-latest]
+        os: [ubuntu-latest, windows-latest, macos-latest]
         python_version: ['3.7']
     timeout-minutes: 180
     steps:
@@ -55,3 +55,24 @@ jobs:
     - name: Test cibuildwheel
       run: |
         python ./bin/run_tests.py
+
+  test-emulated:
+    name: Test emulated cibuildwheel using qemu
+    runs-on: ubuntu-latest
+    timeout-minutes: 180
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions/setup-python@v2
+    - name: Install dependencies
+      run: |
+        python -m pip install -r requirements-dev.txt
+
+    - name: Set up QEMU
+      id: qemu
+      uses: docker/setup-qemu-action@v1
+      with:
+        platforms: all
+
+    - name: Run the emulation tests
+      run: |
+        pytest --run-emulation test/test_emulation.py

bin/run_example_ci_configs.py

@@ -8,6 +8,7 @@ import sys
 import textwrap
 import time
 import click
+from glob import glob
 from collections import namedtuple
 from urllib.parse import quote
 
@@ -30,49 +31,70 @@ def generate_basic_project(path):
     project.generate(path)
 
 
-CIService = namedtuple('CIService', 'name src_config_path dst_config_path badge_md')
+CIService = namedtuple('CIService', 'name dst_config_path badge_md')
 services = [
     CIService(
         name='appveyor',
-        src_config_path='examples/appveyor-minimal.yml',
         dst_config_path='appveyor.yml',
         badge_md='[![Build status](https://ci.appveyor.com/api/projects/status/wbsgxshp05tt1tif/branch/{branch}?svg=true)](https://ci.appveyor.com/project/joerick/cibuildwheel/branch/{branch})',
     ),
     CIService(
         name='azure-pipelines',
-        src_config_path='examples/azure-pipelines-minimal.yml',
         dst_config_path='azure-pipelines.yml',
         badge_md='[![Build Status](https://dev.azure.com/joerick0429/cibuildwheel/_apis/build/status/joerick.cibuildwheel?branchName={branch})](https://dev.azure.com/joerick0429/cibuildwheel/_build/latest?definitionId=2&branchName={branch})',
     ),
     CIService(
-        name='circle-ci',
-        src_config_path='examples/circleci-minimal.yml',
+        name='circleci',
         dst_config_path='.circleci/config.yml',
         badge_md='[![CircleCI](https://circleci.com/gh/joerick/cibuildwheel/tree/{branch_escaped}.svg?style=svg)](https://circleci.com/gh/joerick/cibuildwheel/tree/{branch})',
     ),
     CIService(
         name='github',
-        src_config_path='examples/github-minimal.yml',
         dst_config_path='.github/workflows/example.yml',
         badge_md='[![Build](https://github.com/joerick/cibuildwheel/workflows/Build/badge.svg?branch={branch})](https://github.com/joerick/cibuildwheel/actions)',
     ),
     CIService(
         name='travis-ci',
-        src_config_path='examples/travis-ci-minimal.yml',
         dst_config_path='.travis.yml',
         badge_md='[![Build Status](https://travis-ci.org/joerick/cibuildwheel.svg?branch={branch})](https://travis-ci.org/joerick/cibuildwheel)',
     ),
     CIService(
         name='gitlab',
-        src_config_path='examples/gitlab-minimal.yml',
         dst_config_path='.gitlab-ci.yml',
         badge_md='[![Gitlab](https://gitlab.com/joerick/cibuildwheel/badges/{branch}/pipeline.svg)](https://gitlab.com/joerick/cibuildwheel/-/commits/{branch})'
     ),
 ]
 
 
+def ci_service_for_config_file(config_file):
+    service_name = Path(config_file).name.rsplit('-', 1)[0]
+
+    for service in services:
+        if service.name == service_name:
+            return service
+
+    raise ValueError(f'unknown ci service for config file {config_file}')
+
+
 @click.command()
-def run_example_ci_configs():
+@click.argument('config_files', nargs=-1, type=click.Path())
+def run_example_ci_configs(config_files=None):
+    '''
+        Test the example configs. If no files are specified, will test
+        examples/*-minimal.yml
+    '''
+
+    if len(config_files) == 0:
+        config_files = glob('examples/*-minimal.yml')
+
+    # check each CI service has at most 1 config file
+    configs_by_service = {}
+    for config_file in config_files:
+        service = ci_service_for_config_file(config_file)
+        if service.name in configs_by_service:
+            raise Exception('You cannot specify more than one config per CI service')
+        configs_by_service[service.name] = config_file
+
     if git_repo_has_changes():
         print('Your git repo has uncommitted changes. Commit or stash before continuing.')
         exit(1)
@@ -91,18 +113,19 @@ def run_example_ci_configs():
         example_project = Path('example_root')
         generate_basic_project(example_project)
 
-        for service in services:
-            src_config_file = Path(service.src_config_path)
+        for config_file in config_files:
+            service = ci_service_for_config_file(config_file)
+            src_config_file = Path(config_file)
             dst_config_file = example_project / service.dst_config_path
 
             dst_config_file.parent.mkdir(parents=True, exist_ok=True)
             shutil.copyfile(src_config_file, dst_config_file)
 
         run(['git', 'add', example_project], check=True)
-        run(['git', 'commit', '-m', textwrap.dedent(f'''
+        run(['git', 'commit', '--no-verify', '-m', textwrap.dedent(f'''
             Test example minimal configs
 
-            Testing files: {[s.src_config_path for s in services]}
+            Testing files: {config_files}
             Generated from branch: {previous_branch}
             Time: {timestamp}
         ''')], check=True)
@@ -116,9 +139,10 @@ def run_example_ci_configs():
         print('> ')
         print('> | Service | Config | Status |')
         print('> |---|---|---|')
-        for service in services:
+        for config_file in config_files:
+            service = ci_service_for_config_file(config_file)
             badge = service.badge_md.format(branch=branch_name, branch_escaped=quote(branch_name, safe=''))
-            print(f'> | {service.name} | `{service.src_config_path}` | {badge} |')
+            print(f'> | {service.name} | `{config_file}` | {badge} |')
         print('> ')
         print('> Generated by `bin/run_example_ci_config.py`')
         print()

cibuildwheel/__main__.py

@@ -17,6 +17,7 @@ from cibuildwheel.environment import (
     parse_environment,
 )
 from cibuildwheel.util import (
+    Architecture,
     BuildOptions,
     BuildSelector,
     DependencyConstraints,
@@ -67,6 +68,17 @@ def main() -> None:
                             run in Windows, and it will build and test for all versions of
                             Python. Default: auto.
                         ''')
+
+    parser.add_argument('--archs',
+                        default=None,
+                        help='''
+                            Comma-separated list of CPU architectures to build for.
+                            When set to 'auto', builds the architectures natively supported
+                            on this machine. Set this option to build an architecture
+                            via emulation, for example, using binfmt_misc and QEMU.
+                            Default: auto.
+                            Choices: auto, {}
+                        '''.format(", ".join(a.name for a in Architecture)))
     parser.add_argument('--output-dir',
                         default=os.environ.get('CIBW_OUTPUT_DIR', 'wheelhouse'),
                         help='Destination folder for the wheels.')
@@ -168,8 +180,14 @@ def main() -> None:
         print('cibuildwheel: Could not find setup.py, setup.cfg or pyproject.toml at root of package', file=sys.stderr)
         exit(2)
 
+    if args.archs is not None:
+        archs_config_str = args.archs
+    else:
+        archs_config_str = get_option_from_environment('CIBW_ARCHS', platform=platform, default='auto')
+    archs = Architecture.parse_config(archs_config_str, platform=platform)
+
     if args.print_build_identifiers:
-        print_build_identifiers(platform, build_selector)
+        print_build_identifiers(platform, build_selector, archs)
         exit(0)
 
     manylinux_images: Optional[Dict[str, str]] = None
@@ -202,6 +220,7 @@ def main() -> None:
             manylinux_images[build_platform] = image
 
     build_options = BuildOptions(
+        architectures=archs,
         package_dir=package_dir,
         output_dir=output_dir,
         test_command=test_command,
@@ -284,10 +303,12 @@ 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 +1,3 @@
-import platform
 import subprocess
 import sys
 import textwrap
@@ -8,29 +7,10 @@ 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)
-
-
-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,
+)
 
 
 class PythonConfiguration(NamedTuple):
@@ -43,7 +23,9 @@ 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'),
@@ -78,8 +60,14 @@ 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)]
+
+    # return all configurations whose arch is in our `architectures` list,
+    # and match the build/skip rules
+    return [
+        c for c in python_configurations
+        if any(c.identifier.endswith(arch.value) for arch in architectures)
+        and build_selector(c.identifier)
+    ]
 
 
 def build(options: BuildOptions) -> None:
@@ -93,7 +81,7 @@ 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/macos.py

@@ -4,13 +4,14 @@ import shutil
 import subprocess
 import sys
 import tempfile
+import textwrap
 from os import PathLike
 from pathlib import Path
 from typing import Dict, List, NamedTuple, Optional, Sequence, Union
 
 from .environment import ParsedEnvironment
 from .logger import log
-from .util import (BuildOptions, BuildSelector, NonPlatformWheelError,
+from .util import (Architecture, BuildOptions, BuildSelector, NonPlatformWheelError,
                    download, get_build_verbosity_extra_flags, get_pip_script,
                    install_certifi_script, prepare_command)
 
@@ -186,6 +187,12 @@ def setup_python(python_configuration: PythonConfiguration,
 
 
 def build(options: BuildOptions) -> None:
+    if options.architectures != [Architecture.x86_64]:
+        raise ValueError(textwrap.dedent(f'''
+            Invalid archs option {options.architectures}. macOS only supports x86_64 for the moment.
+            If you want to set emulation architectures on Linux, use CIBW_ARCHS_LINUX instead.
+        '''))
+
     temp_dir = Path(tempfile.mkdtemp(prefix='cibuildwheel'))
     built_wheel_dir = temp_dir / 'built_wheel'
     repaired_wheel_dir = temp_dir / 'repaired_wheel'

cibuildwheel/util.py

@@ -1,4 +1,6 @@
 import os
+import platform as platform_module
+import re
 import ssl
 import textwrap
 import urllib.request
@@ -121,10 +123,45 @@ class DependencyConstraints:
         return f'{self.__class__.__name__}{self.base_file_path!r})'
 
 
+class Architecture(Enum):
+    # mac/linux archs
+    x86_64 = 'x86_64'
+    i686 = 'i686'
+    aarch64 = 'aarch64'
+    ppc64le = 'ppc64le'
+    s390x = 's390x'
+
+    # windows archs
+    x86 = 'x86'
+    AMD64 = 'AMD64'
+
+    @staticmethod
+    def parse_config(config: str, platform: str) -> 'List[Architecture]':
+        result = []
+        for arch_str in re.split(r'[\s,]+', config):
+            if arch_str == 'auto':
+                result += Architecture.auto_archs(platform=platform)
+            else:
+                result.append(Architecture(arch_str))
+        return result
+
+    @staticmethod
+    def auto_archs(platform: str) -> 'List[Architecture]':
+        native_architecture = Architecture(platform_module.machine())
+        result = [native_architecture]
+        if platform == 'linux' and native_architecture == Architecture.x86_64:
+            # x86_64 machines can run i686 docker containers
+            result.append(Architecture.i686)
+        if platform == 'windows' and native_architecture == Architecture.AMD64:
+            result.append(Architecture.x86)
+        return result
+
+
 class BuildOptions(NamedTuple):
     package_dir: Path
     output_dir: Path
     build_selector: BuildSelector
+    architectures: List[Architecture]
     environment: ParsedEnvironment
     before_all: str
     before_build: Optional[str]
@@ -164,7 +201,7 @@ def strtobool(val: str) -> bool:
     return False
 
 
-class CIProvider(str, Enum):
+class CIProvider(Enum):
     travis_ci = 'travis'
     appveyor = 'appveyor'
     circle_ci = 'circle_ci'

cibuildwheel/windows.py

@@ -3,6 +3,7 @@ import shutil
 import subprocess
 import sys
 import tempfile
+import textwrap
 from os import PathLike
 from pathlib import Path
 from typing import Dict, List, NamedTuple, Optional, Sequence, Union
@@ -12,7 +13,7 @@ import toml
 
 from .environment import ParsedEnvironment
 from .logger import log
-from .util import (BuildOptions, BuildSelector, NonPlatformWheelError,
+from .util import (Architecture, BuildOptions, BuildSelector, NonPlatformWheelError,
                    download, get_build_verbosity_extra_flags, get_pip_script,
                    prepare_command)
 
@@ -201,6 +202,13 @@ def pep_518_cp35_workaround(package_dir: Path, env: Dict[str, str]) -> None:
 
 
 def build(options: BuildOptions) -> None:
+    if options.architectures != [Architecture.AMD64, Architecture.x86]:
+        raise ValueError(textwrap.dedent(f'''
+            Invalid archs option {options.architectures}. Windows only supports 'amd64,x86' for the
+            moment. If you want to set emulation architectures on Linux, use CIBW_ARCHS_LINUX
+            instead.
+        '''))
+
     temp_dir = Path(tempfile.mkdtemp(prefix='cibuildwheel'))
     built_wheel_dir = temp_dir / 'built_wheel'
     repaired_wheel_dir = temp_dir / 'repaired_wheel'

docs/faq.md

@@ -24,6 +24,26 @@ Linux wheels are built in the [`manylinux` docker images](https://github.com/pyp
 
 - Alternative dockers images can be specified with the `CIBW_MANYLINUX_X86_64_IMAGE`, `CIBW_MANYLINUX_I686_IMAGE`, and `CIBW_MANYLINUX_PYPY_X86_64_IMAGE` options to allow for a custom, preconfigured build environment for the Linux builds. See [options](options.md#manylinux-image) for more details.
 
+### Building non-native architectures using emulation  {: #emulation}
+
+cibuildwheel supports building non-native architectures on Linux, via
+emulation through the binfmt_misc kernel feature. The easiest way to use this
+is via the [docker/setup-qemu-action][setup-qemu-action] on Github Actions or
+[tonistiigi/binfmt][binfmt].
+
+[setup-qemu-action]: https://github.com/docker/setup-qemu-action
+[binfmt]: https://hub.docker.com/r/tonistiigi/binfmt
+
+Check out the following config for an example of how to set it up on Github
+Actions. Once QEMU is set up and registered, you just need to set the
+`CIBW_ARCHS_LINUX` environment variable (or use the `--archs` option on
+Linux), and the other architectures are emulated automatically.
+
+> .github/workflows/build.yml
+```yaml
+{% include "../examples/github-with-qemu.yml" %}
+```
+
 ### Building packages with optional C extensions
 
 `cibuildwheel` defines the environment variable `CIBUILDWHEEL` to the value `1` allowing projects for which the C extension is optional to make it mandatory when building wheels.

docs/options.md

@@ -155,6 +155,28 @@ CIBW_SKIP: pp*
   }
 </style>
 
+### `CIBW_ARCHS_LINUX` {: #archs}
+> Build non-native architectures
+
+A space-separated list of architectures to build. Use this in conjunction with
+emulation, such as that provided by [docker/setup-qemu-action][setup-qemu-action]
+or [tonistiigi/binfmt][binfmt], to build architectures other than those your
+machine natively supports.
+
+Options: `auto` `x86_64` `i686` `aarch64` `ppc64le` `s390x`
+
+Default: `auto`, meaning the native archs supported on the build machine. For
+example, on an `x86_64` machine, `auto` expands to `x86_64` and `i686`.
+
+[setup-qemu-action]: https://github.com/docker/setup-qemu-action
+[binfmt]: https://hub.docker.com/r/tonistiigi/binfmt
+
+#### Examples
+
+```yaml
+# On an intel runner with qemu installed, build Intel and ARM wheels
+CIBW_ARCHS_LINUX: "auto aarch64"
+```
 
 ## Build customization
 
@@ -488,7 +510,8 @@ CIBW_BUILD_VERBOSITY: 1
 
 ```text
 usage: cibuildwheel [-h] [--platform {auto,linux,macos,windows}]
-                    [--output-dir OUTPUT_DIR] [--print-build-identifiers]
+                    [--archs ARCHS] [--output-dir OUTPUT_DIR]
+                    [--print-build-identifiers]
                     [package_dir]
 
 Build wheels for all the platforms.
@@ -510,6 +533,12 @@ optional arguments:
                         don't run on your development machine. For "windows",
                         you need to run in Windows, and it will build and test
                         for all versions of Python. Default: auto.
+  --archs ARCHS         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. Default: auto Choices: auto,
+                        x86_64, i686, aarch64, ppc64le, s390x, x86, AMD64
   --output-dir OUTPUT_DIR
                         Destination folder for the wheels.
   --print-build-identifiers

examples/github-deploy.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-18.04, windows-latest, macos-latest]
+        os: [ubuntu-18.04, windows-2019, macos-10.15]
 
     steps:
       - uses: actions/checkout@v2

examples/github-minimal.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-18.04, windows-latest, macos-latest]
+        os: [ubuntu-18.04, windows-2019, macos-10.15]
 
     steps:
       - uses: actions/checkout@v2

examples/github-with-qemu.yml

@@ -0,0 +1,46 @@
+name: Build
+
+on: [push, pull_request]
+
+jobs:
+  build_wheels:
+    name: Build wheels on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-18.04, windows-2019, macos-10.15]
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: actions/setup-python@v2
+        name: Install Python
+        with:
+          python-version: '3.7'
+
+      - name: Install cibuildwheel
+        run: |
+          python -m pip install cibuildwheel==1.7.1
+
+      - name: Install Visual C++ for Python 2.7
+        if: runner.os == 'Windows'
+        run: |
+          choco install vcpython27 -f -y
+
+      - name: Set up QEMU
+        if: runner.os == 'Linux'
+        uses: docker/setup-qemu-action@v1
+        with:
+          platforms: all
+
+      - name: Build wheels
+        run: |
+          python -m cibuildwheel --output-dir wheelhouse
+        env:
+          # configure cibuildwheel to build native archs ('auto'), and some
+          # emulated ones
+          CIBW_ARCHS_LINUX: auto aarch64 ppc64le s390x
+
+      - uses: actions/upload-artifact@v2
+        with:
+          path: ./wheelhouse/*.whl

test/conftest.py

@@ -0,0 +1,21 @@
+import pytest
+
+
+def pytest_addoption(parser):
+    parser.addoption(
+        "--run-emulation", action="store_true", default=False, help="run emulation tests"
+    )
+
+
+def pytest_configure(config):
+    config.addinivalue_line("markers", "emulation: mark test requiring qemu binfmt_misc to run")
+
+
+def pytest_collection_modifyitems(config, items):
+    if config.getoption("--run-emulation"):
+        # --run-emulation given in cli: do not skip emulation tests
+        return
+    skip_emulation = pytest.mark.skip(reason="need --run-emulation option to run")
+    for item in items:
+        if "emulation" in item.keywords:
+            item.add_marker(skip_emulation)

test/test_emulation.py

@@ -0,0 +1,53 @@
+import subprocess
+import pytest
+from . import utils
+from . import test_projects
+
+
+project_with_a_test = test_projects.new_c_project()
+
+project_with_a_test.files['test/spam_test.py'] = r'''
+import spam
+
+def test_spam():
+    assert spam.system('python -c "exit(0)"') == 0
+    assert spam.system('python -c "exit(1)"') != 0
+'''
+
+
+@pytest.mark.emulation
+def test(tmp_path):
+    project_dir = tmp_path / 'project'
+    project_with_a_test.generate(project_dir)
+
+    # build and test the wheels
+    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
+        'CIBW_TEST_REQUIRES': 'pytest',
+        'CIBW_TEST_COMMAND': 'pytest {project}/test',
+        'CIBW_ARCHS': 'aarch64 ppc64le s390x',
+    })
+
+    # also check that we got the right wheels
+    expected_wheels = (
+        utils.expected_wheels('spam', '0.1.0', machine_arch='aarch64')
+        + utils.expected_wheels('spam', '0.1.0', machine_arch='ppc64le')
+        + utils.expected_wheels('spam', '0.1.0', machine_arch='s390x')
+    )
+    assert set(actual_wheels) == set(expected_wheels)
+
+
+def test_setting_arch_on_other_platforms(tmp_path, capfd):
+    if utils.platform == 'linux':
+        pytest.skip('this test checks the behaviour on platforms other than linux')
+
+    project_dir = tmp_path / 'project'
+    project_with_a_test.generate(project_dir)
+
+    # build and test the wheels
+    with pytest.raises(subprocess.CalledProcessError):
+        utils.cibuildwheel_run(project_dir, add_env={
+            'CIBW_ARCHS': 'aarch64',
+        })
+
+    captured = capfd.readouterr()
+    assert "Invalid archs option" in captured.err

test/utils.py

@@ -76,7 +76,7 @@ def cibuildwheel_run(project_path, package_dir='.', env=None, add_env=None, outp
 
 
 def expected_wheels(package_name, package_version, manylinux_versions=None,
-                    macosx_deployment_target='10.9'):
+                    macosx_deployment_target='10.9', machine_arch=None):
     '''
     Returns a list of expected wheels from a run of cibuildwheel.
     '''
@@ -85,15 +85,18 @@ def expected_wheels(package_name, package_version, manylinux_versions=None,
     # {python tag} and {abi tag} are closely related to the python interpreter used to build the wheel
     # so we'll merge them below as python_abi_tag
 
+    if machine_arch is None:
+        machine_arch = pm.machine()
+
     if manylinux_versions is None:
-        if pm.machine() == 'x86_64':
+        if machine_arch == 'x86_64':
             manylinux_versions = ['manylinux1', 'manylinux2010']
         else:
             manylinux_versions = ['manylinux2014']
 
     python_abi_tags = ['cp35-cp35m', 'cp36-cp36m', 'cp37-cp37m', 'cp38-cp38', 'cp39-cp39']
 
-    if pm.machine() in ['x86_64', 'AMD64', 'x86']:
+    if machine_arch in ['x86_64', 'AMD64', 'x86']:
         python_abi_tags += ['cp27-cp27m', 'pp27-pypy_73', 'pp36-pypy36_pp73', 'pp37-pypy37_pp73']
 
         if platform == 'linux':
@@ -105,9 +108,9 @@ def expected_wheels(package_name, package_version, manylinux_versions=None,
         platform_tags = []
 
         if platform == 'linux':
-            architectures = [pm.machine()]
+            architectures = [machine_arch]
 
-            if pm.machine() == 'x86_64' and python_abi_tag.startswith('cp'):
+            if machine_arch == 'x86_64' and python_abi_tag.startswith('cp'):
                 architectures.append('i686')
 
             platform_tags = [

unit_test/main_tests/conftest.py

@@ -70,5 +70,14 @@ def platform(request, monkeypatch):
 @pytest.fixture
 def intercepted_build_args(platform, monkeypatch):
     intercepted = ArgsInterceptor()
-    monkeypatch.setattr(globals()[platform], 'build', intercepted)
+
+    if platform == 'linux':
+        monkeypatch.setattr(linux, 'build', intercepted)
+    elif platform == 'macos':
+        monkeypatch.setattr(macos, 'build', intercepted)
+    elif platform == 'windows':
+        monkeypatch.setattr(windows, 'build', intercepted)
+    else:
+        raise ValueError(f'unknown platform value: {platform}')
+
     return intercepted

unit_test/main_tests/main_platform_test.py

@@ -1,3 +1,5 @@
+import platform as platform_module
+from cibuildwheel.util import Architecture
 import sys
 
 import pytest
@@ -64,3 +66,48 @@ def test_platform_environment(platform, intercepted_build_args, monkeypatch):
     main()
 
     assert intercepted_build_args.args[0].package_dir == MOCK_PACKAGE_DIR
+
+
+def test_archs_default(platform, intercepted_build_args, monkeypatch):
+    monkeypatch.setattr(platform_module, 'machine', lambda: 'x86_64')
+
+    main()
+    build_options = intercepted_build_args.args[0]
+
+    if platform == 'linux':
+        assert build_options.architectures == [Architecture.x86_64, Architecture.i686]
+    else:
+        assert build_options.architectures == [Architecture.x86_64]
+
+
+@pytest.mark.parametrize('use_env_var', [False, True])
+def test_archs_argument(platform, intercepted_build_args, monkeypatch, use_env_var):
+    monkeypatch.setattr(platform_module, 'machine', lambda: 'x86_64')
+    if use_env_var:
+        monkeypatch.setenv('CIBW_ARCHS', 'ppc64le')
+    else:
+        monkeypatch.setenv('CIBW_ARCHS', 'unused')
+        monkeypatch.setattr(sys, 'argv', sys.argv + ['--archs', 'ppc64le'])
+
+    main()
+    build_options = intercepted_build_args.args[0]
+
+    assert build_options.architectures == [Architecture.ppc64le]
+
+
+def test_archs_platform_specific(platform, intercepted_build_args, monkeypatch):
+    monkeypatch.setattr(platform_module, 'machine', lambda: 'x86_64')
+    monkeypatch.setenv('CIBW_ARCHS', 'unused')
+    monkeypatch.setenv('CIBW_ARCHS_LINUX', 'ppc64le')
+    monkeypatch.setenv('CIBW_ARCHS_WINDOWS', 'x86')
+    monkeypatch.setenv('CIBW_ARCHS_MACOS', 'x86_64')
+
+    main()
+    build_options = intercepted_build_args.args[0]
+
+    if platform == 'linux':
+        assert build_options.architectures == [Architecture.ppc64le]
+    elif platform == 'windows':
+        assert build_options.architectures == [Architecture.x86]
+    elif platform == 'macos':
+        assert build_options.architectures == [Architecture.x86_64]