Unify rebootstrap mechanisms

Drop special-case hack when the initial and the target Python have
the same version. This used the initial Python to generate the
bin/buildout for the target Python. This could cause issues because
the initial and the target Python are unlikely to share the same
sites-packages, and this influences script generation.

The new rebootstrap mechanism also works when the Python versions
are the same, so it can be used in all cases.

Removing this hack also reduces even more the dependency on private
internal APIs of zc.buildout.

slapos/rebootstrap/__init__.py

@@ -12,9 +12,9 @@
 #
 ##############################################################################
 
-import errno, logging, os, shutil, subprocess, sys, tempfile
+import errno, logging, os, shutil, subprocess, sys
 import pkg_resources
-from zc.buildout import easy_install, UserError
+from zc.buildout import UserError
 
 
 buildout_dist = pkg_resources.get_distribution('zc.buildout')
@@ -25,16 +25,7 @@ if 'slapos' not in str(buildout_dist.version):
     % buildout_dist)
 
 
-class FakeSysExecutable(object):
-
-  def __init__(self, python):
-    self.executable = python
-
-  def __getattr__(self, attr):
-    return getattr(sys, attr)
-
-
-def get_distributions():
+def get_paths():
   # zc.buildout and dependencies
   dists = pkg_resources.require('zc.buildout')
   # propagate slapos.libnetworkcache availability
@@ -44,36 +35,8 @@ def get_distributions():
   except ImportError:
     pass
   # keep same order as in sys.path
-  dists.sort(key=lambda d: sys.path.index(d.location))
-  return dists
-
-
-def get_paths():
-  path = None
-  paths = []
-  # order preserving unique, knowing that duplicates can only be adjacent
-  for dist in get_distributions():
-    if path != dist.location:
-      path = dist.location
-      paths.append(path)
-  return paths
-
-
-def setup_script(path, python=sys.executable):
-  from zc.buildout import easy_install
-  executable_path = os.path.realpath(path)
-  assert os.path.isabs(executable_path)
-  try:
-    if sys.executable != python:
-      easy_install.sys = FakeSysExecutable(python)
-    easy_install.scripts(
-      ((os.path.basename(executable_path), 'zc.buildout.buildout', 'main'),),
-      get_distributions(),
-      python,
-      os.path.dirname(executable_path)
-    )
-  finally:
-    easy_install.sys = sys
+  paths = {d.location for d in dists}
+  return [p for p in sys.path if p in paths]
 
 
 class extension(object):
@@ -132,25 +95,19 @@ Buildout will be restarted automatically to have this change applied.
     if x == '#!' + self.wanted_python:
       shutil.copy(new_bin, installed)
     else:
-      if subprocess.call((self.wanted_python, '-c',
-          'import sys; sys.exit(sys.version_info[:2] == %r)'
-          % (sys.version_info[:2],))):
-        setup_script(new_bin, self.wanted_python)
-        shutil.copy(new_bin, installed)
-      else:
-        old = installed + '-old'
-        shutil.move(installed, old)
-        try:
-          paths = get_paths()
-          args = [arg for arg in sys.argv if arg.startswith('buildout:')]
-          subprocess.check_call(
-            [self.wanted_python, '-c',
-            "import sys ; sys.path[0:0]=%r ; "
-            "import zc.buildout.buildout ; "
-            "sys.argv[1:1]=%r ; "
-            "zc.buildout.buildout.main()" % (paths, args + ['bootstrap'])])
-        except subprocess.CalledProcessError:
-          shutil.move(old, installed)
-          raise
-        shutil.copy(installed, new_bin)
+      old = installed + '-old'
+      shutil.move(installed, old)
+      try:
+        paths = get_paths()
+        args = [arg for arg in sys.argv if arg.startswith('buildout:')]
+        subprocess.check_call(
+          [self.wanted_python, '-c',
+          "import sys ; sys.path[0:0]=%r ; "
+          "import zc.buildout.buildout ; "
+          "sys.argv[1:1]=%r ; "
+          "zc.buildout.buildout.main()" % (paths, args + ['bootstrap'])])
+      except subprocess.CalledProcessError:
+        shutil.move(old, installed)
+        raise
+      shutil.copy(installed, new_bin)
     os.execve(self.wanted_python, [self.wanted_python] + sys.argv, self.environ)

slapos/rebootstrap/same_version.txt

@@ -35,7 +35,7 @@ is available, and buildout is using another python:
 Buildout will be restarted automatically to have this change applied.
 ************ REBOOTSTRAP: IMPORTANT NOTICE ************
 <BLANKLINE>
-Generated script '/sample-buildout/bin/buildout-rebootstrap'.
+Generated script '/sample-buildout/bin/buildout'.
 Develop: '/sample-buildout/recipes'
 Updating installpython.
 Installing realrun.