ci: add script to detect latest Kubernetes patch release

By using this script, we can pass Kubernetes versions like v1.19 to the
CI jobs. The jobs are then responsible for detecting the a full release
version, including the '.patch' suffix.

Versions are passed as 1.19, releases have the 'v' prefix as in v1.19.1.

Signed-off-by: Niels de Vos <ndevos@redhat.com>

scripts/get_patch_release.py

@@ -0,0 +1,76 @@
+#!/usr/bin/python
+'''
+Fetches the Kubernetes releases from GitHub and returns the most recent patch
+release for a major version.
+
+Parameters:
+ --version=<version>: the major version to find the latest patch release for, i.e. v1.19
+'''
+
+import argparse
+import sys
+import requests
+
+RELEASE_URL = 'https://api.github.com/repos/kubernetes/kubernetes/releases'
+'''
+URL for fetching the releases. Add '?per_num=50' to increase the number of
+returned releases from default 30 to 50 (max 100).
+'''
+
+
+def get_json_releases():
+    '''
+    Fetch the releases from GitHub, return the full JSON structures that were
+    obtained.
+    '''
+    headers = {'Accept': 'application/vnd.github.v3+json'}
+    res = requests.get(RELEASE_URL, headers=headers)
+    return res.json()
+
+
+def get_releases(gh_releases):
+    '''
+    Take the JSON formatted releases, and return a list of the name for each label.
+    '''
+    releases = list()
+    for release in gh_releases:
+        releases.append(release['name'])
+    return releases
+
+
+def main():
+    '''
+    main() function to parse arguments and run the actions.
+    '''
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--version', help='major version to find patch release for')
+    args = parser.parse_args()
+
+    # get all the releases
+    json = get_json_releases()
+    releases = get_releases(json)
+
+    # in case --version is passed, exit with 0 or 1
+    if args.version:
+        version = args.version
+        if not version.startswith('v'):
+            version = 'v' + version
+
+        # releases are ordered from newest to oldest, so the 1st match is the
+        # most current patch update
+        for release in releases:
+            if release.startswith(version + '.'):
+                print(release)
+                sys.exit(0)
+
+        # no match, exit with an error
+        sys.exit(1)
+    # --version was not passed, list all releases
+    else:
+        for release in releases:
+            print(release)
+
+    sys.exit(0)
+
+if __name__ == '__main__':
+    main()