Remove virtualenv activation

Since the original merge of this code
(04208e7c79) several things have
changed; particularly now we ship dib-run-parts as part of dib, not as
a separate package.

We setup $_LIB to point to the shipped library diretory via
pkg_resources lookups.  We now call dib-run-parts (as mentioned,
shipped as a dib library now), source scripts, etc. via $_LIB and thus
do not rely on $PATH.  Consequently we don't need this activation
part.

Which is helpful, because "venv" (as opposed to virtualenv) doesn't
have activate_this.py.  So this fixes installation under that for
Python 3.

We update the functional tests to use the virtualenv_command exported
by the ensure-pip role, which will test the venv path.  There is no
need for dib_python as we are Python 3 only now.

Change-Id: Iede929ea2d278008220aac8b1d678ba41eba0d8a

diskimage_builder/disk_image_create.py

@@ -12,58 +12,14 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-from __future__ import print_function
-
 import os
 import os.path
-import runpy
 import sys
 
 import diskimage_builder.paths
 
 
-# borrowed from pip:locations.py
-def running_under_virtualenv():
-    """Return True if we're running inside a virtualenv, False otherwise."""
-    if hasattr(sys, 'real_prefix'):
-        return True
-    elif sys.prefix != getattr(sys, "base_prefix", sys.prefix):
-        return True
-    return False
-
-
-def activate_venv():
-    if running_under_virtualenv():
-        activate_this = os.path.join(sys.prefix, "bin", "activate_this.py")
-        try:
-            globs = runpy.run_path(activate_this, globals())
-            globals().update(globs)
-            del globs
-        # TODO(dtantsur): replace with FileNotFoundError when Python 2 is no
-        # longer supported.
-        except OSError:
-            print("WARNING: A virtual environment was detected, but the "
-                  "activate_this.py script was not found. You may need to set "
-                  "PATH manually", file=sys.stderr)
-
-
 def main():
-    # If we are called directly from a venv install
-    # (/path/venv/bin/disk-image-create) then nothing has added the
-    # virtualenv bin/ dir to $PATH.  the exec'd script below will be
-    # unable to find call other dib tools like dib-run-parts.
-    #
-    # One solution is to say that you should only ever run
-    # disk-image-create in a shell that has already sourced
-    # bin/activate.sh (all this really does is add /path/venv/bin to
-    # $PATH).  That's not a great interface as resulting errors will
-    # be very non-obvious.
-    #
-    # We can detect if we are running in a virtualenv and use
-    # virtualenv's "activate_this.py" script to activate it ourselves
-    # before we call the script.  This ensures we have the path setting
-    activate_venv()
-
     environ = os.environ
 
     # pre-seed some paths for the shell script
@@ -74,7 +30,7 @@ def main():
         os.environ['DIB_PYTHON_EXEC'] = sys.executable
 
     # we have to handle being called as "disk-image-create" or
-    # "ramdisk-image-create".  ramdisk-iamge-create is just a symlink
+    # "ramdisk-image-create".  ramdisk-image-create is just a symlink
     # to disk-image-create
     # XXX: we could simplify things by removing the symlink, and
     # just setting IS_RAMDISK in environ here depending on sys.argv[1]

playbooks/dib-functests/run.yaml

@@ -1,7 +1,7 @@
 - hosts: all
   name: Run dib functional tests
   roles:
-    - ensure-virtualenv
+    - ensure-pip
     - bindep
     - dib-setup-gate-mirrors
     - dib-functests

releasenotes/notes/virtualenv-activation-6de5738c9db8241d.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    This removes automatic detection and activation of virtualenv
+    environments, which is no longer necessary.  This fixes installation
+    under Python 3's inbuilt ``venv`` module.

roles/dib-functests/defaults/main.yaml

@@ -1,5 +1,4 @@
 ---
-dib_python: python3
 dib_virtualenv: "{{ ansible_user_dir }}/dib-venv"
 dib_functests: []
 # This is a bit of hack; it allows us to template out jobs where the

roles/dib-functests/tasks/main.yaml

@@ -25,7 +25,7 @@
   pip:
     name: "file://{{ ansible_user_dir }}/{{ zuul.project.src_dir }}"
     virtualenv: "{{ dib_virtualenv }}"
-    virtualenv_python: "{{ dib_python }}"
+    virtualenv_command: "{{ ensure_pip_virtualenv_command }}"
     extra_args: "-c {{ upper_constraints }}"
 
 - name: Setup log output