sandboxing uranium separately from the application

setup.py

@@ -22,7 +22,7 @@
 ]
 
 setup(name='uranium',
-      version='0.0.25',
+      version='0.0.26',
       description='a build system for python',
       long_description='a build system for python',
       author='Yusuke Tsutsumi',

uranium/__init__.py

@@ -18,6 +18,7 @@
 from docopt import docopt
 from virtualenv import make_environment_relocatable
 from .uranium import Uranium
+from .virtualenv_manager import install_virtualenv
 from .config import load_config_from_file
 import os
 import sys
@@ -44,6 +45,8 @@ def _get_uranium(uranium_file):
 
 @contextmanager
 def in_virtualenv(path):
+    install_virtualenv(path)
+
     # we activate the virtualenv
     _activate_virtualenv(path)
 
@@ -63,6 +66,7 @@ def _activate_virtualenv(uranium_dir):
     # we modify the executable directly, because pip invokes this to install packages.
     sys.executable = os.path.join(uranium_dir, 'bin', 'python')
 
+
 def _create_stdout_logger():
     """ create a logger to stdout """
     log = logging.getLogger(__name__)

uranium/virtualenv_manager.py

@@ -0,0 +1,71 @@
+import io
+import logging
+import os
+import subprocess
+import shutil
+import sys
+import tarfile
+import tempfile
+
+try:
+    from urllib2 import urlopen as urlopen
+except:
+    from urllib.request import urlopen as urlopen
+
+VENV_URL = "https://pypi.python.org/packages/source/v/virtualenv/virtualenv-{major}.{minor}.{rev}.tar.gz"
+VENV_MAJOR = 1
+VENV_MINOR = 11
+VENV_REV = 6
+
+LOGGER = logging.getLogger(__name__)
+
+
+def install_virtualenv(install_dir):
+    if is_virtualenv(install_dir):
+        return
+
+    temp_dir = tempfile.mkdtemp()
+    try:
+        download_virtualenv(temp_dir)
+        virtualenv_dir = os.path.join(temp_dir, "virtualenv-{major}.{minor}.{rev}".format(
+            major=VENV_MAJOR, minor=VENV_MINOR, rev=VENV_REV
+        ))
+        virtualenv_executable = os.path.join(virtualenv_dir, 'virtualenv.py')
+        os.chdir(virtualenv_dir)  # virtualenv only works in the cwd it is installed in
+        subprocess.call([sys.executable, virtualenv_executable,
+                         '--no-site-packages',
+                         '--always-copy',
+                         install_dir])
+        os.chdir(install_dir)
+    finally:
+        shutil.rmtree(temp_dir)
+
+
+def download_virtualenv(target_dir=None):
+    target_dir = target_dir or os.path.abspath(os.curdir)
+    venv_url = VENV_URL.format(
+        major=VENV_MAJOR, minor=VENV_MINOR, rev=VENV_REV
+    )
+    extract_tar(venv_url, target_dir)
+
+
+def extract_tar(url, target_dir):
+    """ Return a bytesio object with a download bar """
+    LOGGER.info("Downloading url: {0}".format(url))
+    fileobj = io.BytesIO(urlopen(url).read())
+    tf = tarfile.TarFile.open(fileobj=fileobj)
+    LOGGER.info("extracting to {0}...".format(target_dir))
+    tf.extractall(target_dir)
+
+VIRTUALENV_FILES = {
+    'activate file': os.path.join('bin', 'activate')
+}
+
+
+def is_virtualenv(path):
+    """ validate if the path is already a virtualenv """
+    for name, venv_path in VIRTUALENV_FILES.items():
+        target_path = os.path.join(path, venv_path)
+        if not os.path.exists(target_path):
+            return False
+    return True