add check-python2-support command

Change-Id: I3406acd2b1fea353fd1419cbe1aacc2b09588a3c
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

openstack_requirements/cmds/check_py2.py

@@ -0,0 +1,78 @@
+#! /usr/bin/env python
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from __future__ import print_function
+
+import argparse
+
+import pkg_resources
+import requests
+
+
+_url_template = 'https://pypi.python.org/pypi/{dist}/{version}/json'
+
+
+def _get_metadata(dist, version):
+    try:
+        url = _url_template.format(dist=dist, version=version)
+        response = requests.get(url)
+        return response.json()
+    except ValueError:
+        return {}
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        '--verbose', '-v',
+        default=False,
+        action='store_true',
+        help='turn on noisy output',
+    )
+    parser.add_argument(
+        '--requirements',
+        default='upper-constraints.txt',
+        help='the list of constrained requirements to check',
+    )
+    args = parser.parse_args()
+
+    for line in open(args.requirements, 'r'):
+        try:
+            req = pkg_resources.Requirement.parse(line)
+        except ValueError:
+            # Assume this is a comment and skip it.
+            continue
+        # req.specifier is a set so we can't get an item out of it
+        # directly. Turn it into a list and take the first (and only)
+        # value. That gives us an _IndividualSpecifier which has a
+        # version attribute that is not smart enough to filter out the
+        # selector value for things like python version, so drop
+        # anything after the first semicolon.
+        version = list(req.specifier)[0].version.split(';')[0]
+        data = _get_metadata(req.project_name, version)
+        classifiers = data.get('info', {}).get('classifiers', [])
+        for classifier in classifiers:
+            if classifier.startswith('Programming Language :: Python :: 2'):
+                if args.verbose:
+                    print('{}==={} {!r}'.format(
+                        req.project_name, version, classifier))
+                break
+        else:
+            print('\nNo "Python :: 2" classifier found for {}==={}'.format(
+                req.project_name, version))
+            for classifier in classifiers:
+                print('  {}'.format(classifier))
+
+if __name__ == '__main__':
+    main()

setup.cfg

@@ -39,3 +39,4 @@ console_scripts =
     validate-constraints = openstack_requirements.cmds.validate:main
     validate-projects = openstack_requirements.cmds.validate_projects:main
     normalize-requirements = openstack_requirements.cmds.normalize_requirements:main
+    check-python2-support = openstack_requirements.cmds.check_py2:main