Add Zuul job for testing GitHub WIP status

Add a kata-github-wip Zuul job that can be used to test
for presence of specific WIP PR labels or specific WIP
keywords in the PR title and block the PR accordingly.

Suppress the placeholder job that was added just to
pass initial tests.

Change-Id: I4f50c77e19f1e76bf65ebfcb9ea587e0556dda03

playbooks/github-wip/run.yaml

@@ -0,0 +1,4 @@
+- hosts: localhost
+  roles:
+    - role: check-github-pr-is-wip
+      github_pr: "{{ zuul.change_url }}"

playbooks/placeholder/run.yaml

@@ -1,5 +0,0 @@
-- hosts: localhost
-  tasks:
-    - name: Call the placeholder role
-      include_role:
-        name: placeholder

roles/check-github-pr-is-wip/README.rst

@@ -0,0 +1,17 @@
+Fail if any WIP labels are attached to a given GitHub PR, or if
+any WIP keywords are included in a given GitHub PR title.
+
+**Role Variables**
+
+.. zuul:rolevar:: github_pr
+
+   URL for the GitHub PR to check. Should be something like:
+   https://github.com/kata-containers/runtime/pull/1112
+
+.. zuul:rolevar:: wip_labels
+
+   Space-separated label names to consider as WIP labels.
+
+.. zuul:rolevar:: wip_keywords
+
+   Space-separated keywords to consider as WIP keywords in PR titles.

roles/check-github-pr-is-wip/files/github_wip.py

@@ -0,0 +1,68 @@
+#!/usr/bin/python3
+#
+# Job testing a GitHub PR for presence of specific WIP labels
+# or specific WIP keywords in PR title, in order to block merging.
+#
+# Copyright 2018 Thierry Carrez <thierry@openstack.org>
+# All Rights Reserved.
+#
+#    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.
+
+import argparse
+import json
+import re
+import sys
+import urllib.request
+
+
+def get_github_PR(change_url):
+    match = re.search('https://github.com/(.+)/pull/(\d+)', change_url)
+    repository = match.group(1)
+    prnumber = match.group(2)
+
+    url = 'https://api.github.com/repos/%s/pulls/%s' % (repository, prnumber)
+
+    with urllib.request.urlopen(url) as link:
+        data = json.loads(link.read().decode())
+    return data
+
+
+def is_wip(change, wip_keywords, wip_labels):
+    for wip_keyword in wip_keywords:
+        if wip_keyword in change['title']:
+            print('%s is mentioned in PR title' % wip_keyword)
+            return True
+
+    for label in change['labels']:
+        for wip_label in wip_labels:
+            if label['name'] == wip_label:
+                print('PR is labeled %s' % wip_label)
+                return True
+
+    print('No blocking marker found, this PR is OK to merge')
+    return False
+
+
+def main():
+    parser = argparse.ArgumentParser(description='Is the PR blocked ?')
+    parser.add_argument('change_url', help='GitHub PR URL')
+    parser.add_argument('keywords', help='Key words in PR title to block on')
+    parser.add_argument('labels', help='Names of labels to block on')
+    args = parser.parse_args()
+
+    change = get_github_PR(args.change_url)
+    sys.exit(is_wip(change, args.keywords.split(), args.labels.split()))
+
+
+if __name__ == "__main__":
+    main()

roles/check-github-pr-is-wip/tasks/main.yaml

@@ -0,0 +1,2 @@
+- name: Check for WIP labels or WIP title keywords on a GitHub PR
+  script: github_wip.py {{ github_pr }} '{{ wip_keywords }}' '{{ wip_labels }}'

roles/placeholder/tasks/main.yaml

@@ -1,2 +0,0 @@
-- name: Placeholder task
-  debug: msg=placeholder

zuul.d/jobs.yaml

@@ -14,3 +14,15 @@
       tox_envlist: linters
       tox_environment:
         ANSIBLE_ROLES_PATH: ~/src/git.openstack.org/openstack-infra/zuul-jobs/roles:~/src/git.openstack.org/kata-containers/zuul-config/roles
+
+- job:
+    name: kata-github-wip
+    description: |
+      This job calls the github-pr playbook with a Kata-curated set of
+      WIP labels and WIP title keywords
+    run: playbooks/github-wip/run.yaml
+    nodeset:
+      nodes: []
+    vars:
+      wip_labels: 'do-not-merge wip rfc'
+      wip_keywords: 'WIP RFC'