Move highest_semver.py from oslo-incubator

Add a script to print the highest SemVer tag when given a list as input.

Change-Id: Icb19338743cd013e855c10d5de25c3ac5b7ec873

README.rst

@@ -445,3 +445,10 @@ Examples:
 To clean up Nova kilo blueprints:
 
 ./autokick.py nova kilo
+
+highest_semver.py
+-----------------
+
+Reads a list of version tags from standard input and prints the
+"highest" value as output, ignoring tags that don't look like valid
+versions.

highest_semver.py

@@ -0,0 +1,54 @@
+#!/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.
+
+"""Read a list of version tags from stdin and pick the one with the
+highest semver value.
+"""
+
+from __future__ import print_function
+
+import fileinput
+import sys
+
+
+tags = []
+for line in fileinput.input(sys.argv[1:]):
+    line = line.strip()
+    if not line:
+        continue
+    parts = line.split('.')
+    try:
+        v = tuple(int(val) for val in parts)
+    except ValueError:
+        # This tag is probably an alpha, so ignore it
+        continue
+    if len(v) == 3:
+        v = v + ('zzz',)  # artifically sort the value higher than alphas
+    # Ignore versions where the beginning doesn't look like a number,
+    # such as 'havana-eol'
+    if not isinstance(v[0], int):
+        continue
+    # Ignore date-based entries
+    if v[0] > 100:
+        continue
+    tags.append(v)
+
+if tags:
+    # We only want to print something if we actually have any tags to
+    # pick from. Otherwise we probably have a library that has never
+    # been released, so there is no valid version.
+    version = max(tags)
+    if version[-1] == 'zzz':
+        version = version[:-1]
+    print('.'.join(str(t) for t in version))