Add an option to allow enabling/disabling build isolation

piptools/repositories/pypi.py

@@ -49,9 +49,10 @@ class PyPIRepository(BaseRepository):
  config), but any other PyPI mirror can be used if index_urls is
  changed/configured on the Finder.
  """
- def __init__(self, pip_options, session):
+ def __init__(self, pip_options, session, build_isolation=False):
  self.session = session
  self.pip_options = pip_options
+ self.build_isolation = build_isolation
 
  index_urls = [pip_options.index_url] + pip_options.extra_index_urls
  if pip_options.no_index:
@@ -161,7 +162,7 @@ def resolve_reqs(self, download_dir, ireq, wheel_cache):
  'download_dir': download_dir,
  'wheel_download_dir': self._wheel_download_dir,
  'progress_bar': 'off',
- 'build_isolation': False
+ 'build_isolation': self.build_isolation,
  }
  resolver_kwargs = {
  'finder': self.finder,

piptools/scripts/compile.py

@@ -61,10 +61,14 @@
 @click.option('--max-rounds', default=10,
  help="Maximum number of rounds before resolving the requirements aborts.")
 @click.argument('src_files', nargs=-1, type=click.Path(exists=True, allow_dash=True))
+@click.option('--build-isolation/--no-build-isolation', is_flag=True, default=False,
+ help="Enable isolation when building a modern source distribution. "
+ "Build dependencies specified by PEP 518 must be already installed "
+ "if build isolation is disabled.")
 def cli(verbose, quiet, dry_run, pre, rebuild, find_links, index_url, extra_index_url,
  cert, client_cert, trusted_host, header, index, emit_trusted_host, annotate,
  upgrade, upgrade_packages, output_file, allow_unsafe, generate_hashes,
- src_files, max_rounds):
+ src_files, max_rounds, build_isolation):
  """Compiles requirements.txt from requirements.in specs."""
  log.verbosity = verbose - quiet
 
@@ -122,7 +126,7 @@ def cli(verbose, quiet, dry_run, pre, rebuild, find_links, index_url, extra_inde
  pip_options, _ = pip_command.parse_args(pip_args)
 
  session = pip_command._build_session(pip_options)
- repository = PyPIRepository(pip_options, session)
+ repository = PyPIRepository(pip_options, session, build_isolation)
 
  upgrade_install_reqs = {}
  # Proxy with a LocalRequirementsRepository if --upgrade is not specified

tests/test_cli_compile.py

@@ -534,3 +534,21 @@ def test_cert_option(MockPyPIRepository, runner, option, attr, expected):
  for call in MockPyPIRepository.call_args_list:
  pip_options = call[0][0]
  assert getattr(pip_options, attr) == expected
+
+
+@pytest.mark.parametrize('option, expected', [
+ ('--build-isolation', True),
+ ('--no-build-isolation', False),
+])
+@mock.patch('piptools.scripts.compile.PyPIRepository')
+def test_build_isolation_option(MockPyPIRepository, runner, option, expected):
+ """
+ A value of the --build-isolation/--no-build-isolation flag must be passed to the PyPIRepository.
+ """
+ with open('requirements.in', 'w'):
+ pass
+
+ runner.invoke(cli, [option])
+
+ # Ensure the build_isolation option in PyPIRepository has the expected value.
+ assert [call[0][2] for call in MockPyPIRepository.call_args_list] == [expected]