#1393 Add system site-packages support in virtualenv (again)

docs/docs/configuration.md

@@ -34,6 +34,7 @@ which will give you something similar to this:
 cache-dir = "/path/to/cache/directory"
 virtualenvs.create = true
 virtualenvs.in-project = false
+virtualenvs.system-packages = false
 virtualenvs.path = "{cache-dir}/virtualenvs"  # /path/to/cache/directory/virtualenvs
 ```
 
@@ -112,6 +113,12 @@ Defaults to `true`.
 Create the virtualenv inside the project's root directory.
 Defaults to `false`.
 
+### `virtualenvs.system-packages`: boolean
+
+Give the virtual environment access to the system site-packages directory.
+Applies on virtualenv creation.
+Defaults to `false`.
+
 ### `virtualenvs.path`: string
 
 Directory where virtual environments will be created.

poetry/config/config.py

@@ -35,6 +35,7 @@ class Config(object):
         "virtualenvs": {
             "create": True,
             "in-project": False,
+            "system-packages": False,
             "path": os.path.join("{cache-dir}", "virtualenvs"),
         },
     }
@@ -130,14 +131,22 @@ def process(self, value):  # type: (Any) -> Any
         return re.sub(r"{(.+?)}", lambda m: self.get(m.group(1)), value)
 
     def _get_validator(self, name):  # type: (str) -> Callable
-        if name in {"virtualenvs.create", "virtualenvs.in-project"}:
+        if name in {
+            "virtualenvs.create",
+            "virtualenvs.in-project",
+            "virtualenvs.system-packages",
+        }:
             return boolean_validator
 
         if name == "virtualenvs.path":
             return str
 
     def _get_normalizer(self, name):  # type: (str) -> Callable
-        if name in {"virtualenvs.create", "virtualenvs.in-project"}:
+        if name in {
+            "virtualenvs.create",
+            "virtualenvs.in-project",
+            "virtualenvs.system-packages",
+        }:
             return boolean_normalizer
 
         if name == "virtualenvs.path":

poetry/console/commands/config.py

@@ -52,6 +52,11 @@ def unique_config_values(self):
             ),
             "virtualenvs.create": (boolean_validator, boolean_normalizer, True),
             "virtualenvs.in-project": (boolean_validator, boolean_normalizer, False),
+            "virtualenvs.system-packages": (
+                boolean_validator,
+                boolean_normalizer,
+                False,
+            ),
             "virtualenvs.path": (
                 str,
                 lambda val: str(Path(val)),

poetry/utils/env.py

@@ -1,4 +1,5 @@
 import base64
+import functools
 import hashlib
 import json
 import os
@@ -483,6 +484,10 @@ def create_venv(
 
         create_venv = self._poetry.config.get("virtualenvs.create")
         root_venv = self._poetry.config.get("virtualenvs.in-project")
+        system_packages = self._poetry.config.get("virtualenvs.system-packages")
+
+        if system_packages and io.is_debug():
+            io.write_line("<debug>Including system site-packages</>")
 
         venv_path = self._poetry.config.get("virtualenvs.path")
         if root_venv:
@@ -607,7 +612,9 @@ def create_venv(
                 "Creating virtualenv <c1>{}</> in {}".format(name, str(venv_path))
             )
 
-            self.build_venv(str(venv), executable=executable)
+            self.build_venv(
+                str(venv), executable=executable, system_packages=system_packages
+            )
         else:
             if force:
                 if not env.is_sane():
@@ -620,7 +627,9 @@ def create_venv(
                     "Recreating virtualenv <c1>{}</> in {}".format(name, str(venv))
                 )
                 self.remove_venv(str(venv))
-                self.build_venv(str(venv), executable=executable)
+                self.build_venv(
+                    str(venv), executable=executable, system_packages=system_packages
+                )
             elif io.is_very_verbose():
                 io.write_line("Virtualenv <c1>{}</> already exists.".format(name))
 
@@ -643,7 +652,7 @@ def create_venv(
         return VirtualEnv(venv)
 
     @classmethod
-    def build_venv(cls, path, executable=None):
+    def build_venv(cls, path, executable=None, system_packages=False):
         if executable is not None:
             # Create virtualenv by using an external executable
             try:
@@ -667,13 +676,17 @@ def build_venv(cls, path, executable=None):
             else:
                 use_symlinks = True
 
-            builder = EnvBuilder(with_pip=True, symlinks=use_symlinks)
+            builder = EnvBuilder(
+                system_site_packages=system_packages,
+                with_pip=True,
+                symlinks=use_symlinks,
+            )
             build = builder.create
         except ImportError:
             # We fallback on virtualenv for Python 2.7
             from virtualenv import create_environment
 
-            build = create_environment
+            build = functools.partial(create_environment, site_packages=system_packages)
 
         build(path)
 

tests/console/commands/env/test_use.py

@@ -16,7 +16,7 @@
 CWD = Path(__file__).parent.parent / "fixtures" / "simple_project"
 
 
-def build_venv(path, executable=None):
+def build_venv(path, executable=None, system_packages=False):
     os.mkdir(path)
 
 
@@ -61,7 +61,9 @@ def test_activate_activates_non_existing_virtualenv_no_envs_file(app, tmp_dir, m
     )
 
     m.assert_called_with(
-        os.path.join(tmp_dir, "{}-py3.7".format(venv_name)), executable="python3.7"
+        os.path.join(tmp_dir, "{}-py3.7".format(venv_name)),
+        executable="python3.7",
+        system_packages=False,
     )
 
     envs_file = TomlFile(Path(tmp_dir) / "envs.toml")

tests/console/commands/test_config.py

@@ -16,6 +16,7 @@ def test_list_displays_default_value_if_not_set(app, config):
 virtualenvs.create = true
 virtualenvs.in-project = false
 virtualenvs.path = {path}  # /foo{sep}virtualenvs
+virtualenvs.system-packages = false
 """.format(
         path=json.dumps(os.path.join("{cache-dir}", "virtualenvs")), sep=os.path.sep
     )
@@ -35,6 +36,7 @@ def test_list_displays_set_get_setting(app, config):
 virtualenvs.create = false
 virtualenvs.in-project = false
 virtualenvs.path = {path}  # /foo{sep}virtualenvs
+virtualenvs.system-packages = false
 """.format(
         path=json.dumps(os.path.join("{cache-dir}", "virtualenvs")), sep=os.path.sep
     )
@@ -82,6 +84,7 @@ def test_list_displays_set_get_local_setting(app, config):
 virtualenvs.create = false
 virtualenvs.in-project = false
 virtualenvs.path = {path}  # /foo{sep}virtualenvs
+virtualenvs.system-packages = false
 """.format(
         path=json.dumps(os.path.join("{cache-dir}", "virtualenvs")), sep=os.path.sep
     )

tests/test_factory.py

@@ -205,3 +205,4 @@ def test_create_poetry_with_local_config(fixture_dir):
 
     assert not poetry.config.get("virtualenvs.in-project")
     assert not poetry.config.get("virtualenvs.create")
+    assert not poetry.config.get("virtualenvs.system-packages")

tests/utils/test_env.py

@@ -95,7 +95,7 @@ def test_env_get_in_project_venv(manager, poetry):
     shutil.rmtree(str(venv.path))
 
 
-def build_venv(path, executable=None):
+def build_venv(path, executable=None, system_packages=False):
     os.mkdir(path)
 
 
@@ -137,7 +137,9 @@ def test_activate_activates_non_existing_virtualenv_no_envs_file(
     venv_name = EnvManager.generate_env_name("simple-project", str(poetry.file.parent))
 
     m.assert_called_with(
-        os.path.join(tmp_dir, "{}-py3.7".format(venv_name)), executable="python3.7"
+        os.path.join(tmp_dir, "{}-py3.7".format(venv_name)),
+        executable="python3.7",
+        system_packages=False,
     )
 
     envs_file = TomlFile(Path(tmp_dir) / "envs.toml")
@@ -255,7 +257,9 @@ def test_activate_activates_different_virtualenv_with_envs_file(
     env = manager.activate("python3.6", NullIO())
 
     m.assert_called_with(
-        os.path.join(tmp_dir, "{}-py3.6".format(venv_name)), executable="python3.6"
+        os.path.join(tmp_dir, "{}-py3.6".format(venv_name)),
+        executable="python3.6",
+        system_packages=False,
     )
 
     assert envs_file.exists()
@@ -307,7 +311,9 @@ def test_activate_activates_recreates_for_different_patch(
     env = manager.activate("python3.7", NullIO())
 
     build_venv_m.assert_called_with(
-        os.path.join(tmp_dir, "{}-py3.7".format(venv_name)), executable="python3.7"
+        os.path.join(tmp_dir, "{}-py3.7".format(venv_name)),
+        executable="python3.7",
+        system_packages=False,
     )
     remove_venv_m.assert_called_with(
         os.path.join(tmp_dir, "{}-py3.7".format(venv_name))
@@ -596,7 +602,9 @@ def test_create_venv_tries_to_find_a_compatible_python_executable_using_generic_
     manager.create_venv(NullIO())
 
     m.assert_called_with(
-        str(Path("/foo/virtualenvs/{}-py3.7".format(venv_name))), executable="python3"
+        str(Path("/foo/virtualenvs/{}-py3.7".format(venv_name))),
+        executable="python3",
+        system_packages=False,
     )
 
 
@@ -620,7 +628,9 @@ def test_create_venv_tries_to_find_a_compatible_python_executable_using_specific
     manager.create_venv(NullIO())
 
     m.assert_called_with(
-        str(Path("/foo/virtualenvs/{}-py3.8".format(venv_name))), executable="python3.8"
+        str(Path("/foo/virtualenvs/{}-py3.8".format(venv_name))),
+        executable="python3.8",
+        system_packages=False,
     )
 
 
@@ -711,6 +721,7 @@ def test_create_venv_uses_patch_version_to_detect_compatibility(
             )
         ),
         executable=None,
+        system_packages=False,
     )
 
 
@@ -750,6 +761,7 @@ def test_create_venv_uses_patch_version_to_detect_compatibility_with_executable(
             )
         ),
         executable="python{}.{}".format(version.major, version.minor - 1),
+        system_packages=False,
     )
 
 
@@ -781,7 +793,9 @@ def test_activate_with_in_project_setting_does_not_fail_if_no_venvs_dir(
     manager.activate("python3.7", NullIO())
 
     m.assert_called_with(
-        os.path.join(str(poetry.file.parent), ".venv"), executable="python3.7"
+        os.path.join(str(poetry.file.parent), ".venv"),
+        executable="python3.7",
+        system_packages=False,
     )
 
     envs_file = TomlFile(Path(tmp_dir) / "virtualenvs" / "envs.toml")
@@ -843,3 +857,15 @@ def test_env_site_packages_should_raise_an_error_if_no_site_packages(tmp_dir):
 
     with pytest.raises(RuntimeError):
         env.site_packages
+
+
+def test_env_system_packages(tmp_path, config):
+    venv_path = tmp_path / "venv"
+    EnvManager(config).build_venv(str(venv_path), system_packages=True)
+    pyvenv_cfg = venv_path / "pyvenv.cfg"
+    if sys.version_info >= (3, 3):
+        assert "include-system-site-packages = true" in pyvenv_cfg.read_text()
+    elif (2, 6) < sys.version_info < (3, 0):
+        assert not venv_path.joinpath(
+            "lib", "python2.7", "no-global-site-packages.txt"
+        ).exists()