Add option to upgrade core deps in build venv

Some packages may require newer versions of core dependencies for
successful execution of the `pip download` or `pip wheel`
commands. Most notable example is Jinja2 and MarkupSafe when
installed on Focal ref pallets/jinja#1496.

At this stage of the process the input from the charm
wheelhouse.txt is not sufficient.

Add an option to upgrade pip and setuptools in the build venv to
deal with these situations.

Fixes: #646
Signed-off-by: Frode Nordahl <[email protected]>

.github/workflows/tests.yml

@@ -54,17 +54,6 @@ jobs:
       with:
         repository: juju-solutions/layer-basic
 
-    - name: Fixup wheelhouse
-      run: |
-        set -euxo pipefail
-        cat << EOF | tee -a tests/charm-minimal/wheelhouse.txt
-        # https://github.com/pallets/jinja/issues/1496
-        #
-        # We ought to teach charm-tools to seed the virtualenv used to build
-        # wheels with newer versions of pip and setuptools.
-        Jinja2<3
-        EOF
-
     - name: Download built charm snap
       uses: actions/download-artifact@v3
       with:
@@ -90,6 +79,7 @@ jobs:
             reactive-charm-build-arguments:
               - -v
               - --binary-wheels-from-source
+              - --upgrade-buildvenv-core-deps
             build-packages:
               - python3-dev
               - libpq-dev

charmtools/build/builder.py

@@ -1205,6 +1205,11 @@ def main(args=None):
                         default=False,
                         help='Use Python and associated tools from the snap '
                              'when building the wheelhouse.')
+    parser.add_argument('--upgrade-buildvenv-core-deps', action='store_true',
+                        default=False,
+                        help='Upgrade core dependencies in virtualenv used to '
+                        'build/download wheels: pip setuptools to the latest '
+                        'version in PyPI.')
     parser.add_argument('charm', nargs="?", default=".", type=path,
                         help='Source directory for charm layer to build '
                              '(default: .)')
@@ -1226,6 +1231,7 @@ def main(args=None):
     WheelhouseTactic.binary_build = build.binary_wheels
     WheelhouseTactic.binary_build_from_source = build.binary_wheels_from_source
     WheelhouseTactic.use_python_from_snap = build.use_python_from_snap
+    WheelhouseTactic.upgrade_deps = build.upgrade_buildvenv_core_deps
 
     configLogging(build)
 

charmtools/build/tactics.py

@@ -1047,6 +1047,7 @@ class WheelhouseTactic(ExactMatch, Tactic):
     binary_build = False
     binary_build_from_source = False
     use_python_from_snap = False
+    upgrade_deps = False
 
     def __init__(self, *args, **kwargs):
         super(WheelhouseTactic, self).__init__(*args, **kwargs)
@@ -1124,13 +1125,20 @@ def _add(self, wheelhouse, *reqs):
         with utils.tempdir(chdir=False) as temp_dir:
             # put in a temp dir first to ensure we track all of the files
             _no_binary_opts = ('--no-binary', ':all:')
-            if self.binary_build_from_source or self.binary_build:
-                self._pip('wheel',
-                          *_no_binary_opts
-                          if self.binary_build_from_source else tuple(),
-                          '-w', temp_dir, *reqs)
-            else:
-                self._pip('download', *_no_binary_opts, '-d', temp_dir, *reqs)
+            try:
+                if self.binary_build_from_source or self.binary_build:
+                    self._pip('wheel',
+                              *_no_binary_opts
+                              if self.binary_build_from_source else tuple(),
+                              '-w', temp_dir, *reqs)
+                else:
+                    self._pip('download', *_no_binary_opts, '-d', temp_dir, *reqs)
+            except BuildError:
+                log.info('Build failed. If you are building on Focal and have '
+                         'Jinja2 or MarkupSafe as part of your dependencies, '
+                         'try passing the `--upgrade-buildvenv-core-deps` '
+                         'argument.')
+                raise
             log.debug('Copying wheels:')
             for wheel in temp_dir.files():
                 log.debug('  ' + wheel.name)
@@ -1242,6 +1250,13 @@ def __call__(self):
                 ('virtualenv', '--python', 'python3', self._venv),
                 env=self._get_env()
             ).exit_on_error()()
+        if self.upgrade_deps:
+            utils.upgrade_venv_core_packages(self._venv, env=self._get_env())
+        log.debug(
+            'Packages in buildvenv:\n{}'
+            .format(
+                utils.get_venv_package_list(self._venv,
+                                            env=self._get_env())))
         if self.per_layer:
             self._process_per_layer(wheelhouse)
         else:

charmtools/utils.py

@@ -651,3 +651,36 @@ def host_env():
         for element in env['PATH'].split(':')
         if not element.startswith('/snap/charm/')])
     return env
+
+
+def upgrade_venv_core_packages(venv_dir, env=None):
+    """Upgrade core dependencies in venv.
+
+    :param venv_dir: Full path to virtualenv in which packages will be upgraded
+    :type venv_dir: str
+    :param env: Environment to use when executing command
+    :type env: Optional[Dict[str,str]]
+    :returns: This function is called for its side effect
+    """
+    log.debug('Upgrade pip and setuptools in virtualenv "{}"'.format(venv_dir))
+    # We can replace this with a call to `python3 -m venv --upgrade-deps` once
+    # support for bionic and focal has been removed.
+    Process((os.path.join(venv_dir, 'bin/pip'),
+             'install', '-U', 'pip', 'setuptools'),
+            env=env).exit_on_error()()
+
+
+def get_venv_package_list(venv_dir, env=None):
+    """Get list of packages and their version in virtualenv.
+
+    :param venv_dir: Full path to virtualenv in which packages will be listed
+    :type venv_dir: str
+    :param env: Environment to use when executing command
+    :type env: Optional[Dict[str,str]]
+    :returns: List of packages with their versions
+    :rtype: str
+    """
+    result = Process((os.path.join(venv_dir, 'bin/pip'), 'list'), env=env)()
+    if result:
+        return result.output
+    result.exit_on_error()

tests/test_utils.py

@@ -60,3 +60,23 @@ def test_host_env(self, mock_environ):
         self.assertDictEqual(
             {'SOME_OTHER_KEY': 'fake-some-other-key', 'PATH': '/usr/bin:/bin'},
             utils.host_env())
+
+    @unittest.mock.patch.object(utils, "Process")
+    def test_upgrade_venv_core_packages(self, mock_Process):
+        utils.upgrade_venv_core_packages('/some/dir', env={'some': 'envvar'})
+        mock_Process.assert_called_once_with(
+            ('/some/dir/bin/pip', 'install', '-U', 'pip', 'setuptools'),
+            env={'some': 'envvar'})
+
+    @unittest.mock.patch("sys.exit")
+    @unittest.mock.patch.object(utils, "Process")
+    def test_get_venv_package_list(self, mock_Process, mock_sys_exit):
+        mock_Process().return_value = utils.ProcessResult('fakecmd', 0, '', '')
+        utils.get_venv_package_list('/some/dir', env={'some': 'envvar'})
+        mock_Process.assert_called_with(
+            ('/some/dir/bin/pip', 'list'),
+            env={'some': 'envvar'})
+        self.assertFalse(mock_sys_exit.called)
+        mock_Process().return_value = utils.ProcessResult('fakecmd', 1, '', '')
+        utils.get_venv_package_list('/some/dir', env={'some': 'envvar'})
+        mock_sys_exit.assert_called_once_with(1)