Bug 794506 - Part 2: Add virtualenv APIs; r=ted

python/mozbuild/mozbuild/base.py

@@ -25,6 +25,8 @@ from .mozconfig import (
     MozconfigLoadException,
     MozconfigLoader,
 )
+from .virtualenv import VirtualenvManager
+
 
 def ancestors(path):
     """Emit the parent directories of a path."""
@@ -86,6 +88,7 @@ class MozbuildObject(ProcessExecutionMixin):
         self._mozconfig = None
         self._config_guess_output = None
         self._config_environment = None
+        self._virtualenv_manager = None
 
     @classmethod
     def from_environment(cls, cwd=None, detect_virtualenv_mozinfo=True):
@@ -206,6 +209,16 @@ class MozbuildObject(ProcessExecutionMixin):
 
         return self._topobjdir
 
+    @property
+    def virtualenv_manager(self):
+        if self._virtualenv_manager is None:
+            self._virtualenv_manager = VirtualenvManager(self.topsrcdir,
+                self.topobjdir, os.path.join(self.topobjdir, '_virtualenv'),
+                sys.stdout, os.path.join(self.topsrcdir, 'build',
+                'virtualenv_packages.txt'))
+
+        return self._virtualenv_manager
+
     @property
     def mozconfig(self):
         """Returns information about the current mozconfig file.
@@ -475,6 +488,10 @@ class MozbuildObject(ProcessExecutionMixin):
         return cls(self.topsrcdir, self.settings, self.log_manager,
             topobjdir=self.topobjdir)
 
+    def _activate_virtualenv(self):
+        self.virtualenv_manager.ensure()
+        self.virtualenv_manager.activate()
+
 
 class MachCommandBase(MozbuildObject):
     """Base class for mach command providers that wish to be MozbuildObjects.

python/mozbuild/mozbuild/virtualenv.py

@@ -60,19 +60,27 @@ class VirtualenvManager(object):
             'virtualenv.py')
 
     @property
-    def python_path(self):
+    def bin_path(self):
+        # virtualenv.py provides a similar API via path_locations(). However,
+        # we have a bit of a chicken-and-egg problem and can't reliably
+        # import virtualenv. The functionality is trivial, so just implement
+        # it here.
         if sys.platform in ('win32', 'cygwin'):
-            return os.path.join(self.virtualenv_root, 'Scripts', 'python.exe')
+            return os.path.join(self.virtualenv_root, 'Scripts')
 
-        return os.path.join(self.virtualenv_root, 'bin', 'python')
+        return os.path.join(self.virtualenv_root, 'bin')
+
+    @property
+    def python_path(self):
+        binary = 'python'
+        if sys.platform in ('win32', 'cygwin'):
+            binary += '.exe'
+
+        return os.path.join(self.bin_path, binary)
 
     @property
     def activate_path(self):
-        if sys.platform in ('win32', 'cygwin'):
-            return os.path.join(self.virtualenv_root, 'Scripts',
-                'activate_this.py')
-
-        return os.path.join(self.virtualenv_root, 'bin', 'activate_this.py')
+        return os.path.join(self.bin_path, 'activate_this.py')
 
     def up_to_date(self):
         """Returns whether the virtualenv is present and up to date."""
@@ -388,6 +396,39 @@ class VirtualenvManager(object):
 
         execfile(self.activate_path, dict(__file__=self.activate_path))
 
+    def install_pip_package(self, package):
+        """Install a package via pip.
+
+        The supplied package is specified using a pip requirement specifier.
+        e.g. 'foo' or 'foo==1.0'.
+
+        If the package is already installed, this is a no-op.
+        """
+        from pip.req import InstallRequirement
+
+        req = InstallRequirement.from_line(package)
+        if req.check_if_exists():
+            return
+
+        args = [
+            'install',
+            '--use-wheel',
+            package,
+        ]
+
+        return self._run_pip(args)
+
+    def _run_pip(self, args):
+        # It's tempting to call pip natively via pip.main(). However,
+        # the current Python interpreter may not be the virtualenv python.
+        # This will confuse pip and cause the package to attempt to install
+        # against the executing interpreter. By creating a new process, we
+        # force the virtualenv's interpreter to be used and all is well.
+        # It /might/ be possible to cheat and set sys.executable to
+        # self.python_path. However, this seems more risk than it's worth.
+        subprocess.check_call([os.path.join(self.bin_path, 'pip')] + args,
+            stderr=subprocess.STDOUT)
+
 
 def verify_python_version(log_handle):
     """Ensure the current version of Python is sufficient."""