checkFeedAsPromise: new python script which can be used to create promises on RSS feeds

setup.py

@@ -65,6 +65,7 @@ setup(name=name,
         'console_scripts': [
           'agent = slapos.agent.agent:main [agent]',
           'check-web-page-http-cache-hit = slapos.promise.check_web_page_http_cache_hit:main',
+          'check-feed-as-promise = slapos.resilient.checkFeedAsPromise:main',
           'clouddestroy = slapos.cloudmgr.destroy:main',
           'cloudgetprivatekey = slapos.cloudmgr.getprivatekey:main',
           'cloudgetpubliciplist = slapos.cloudmgr.getpubliciplist:main',

slapos/resilient/checkFeedAsPromise.py

+# Command line script to test a RSS feed in a promise
+# Checks that a given pattern can be found (or not) in the title or the
+# description of the latest feed item.
+# A time buffer option can be given, so the promise really gets true, or false,
+# only if the last item is older or younger than the allowed time buffer.
+import argparse
+import datetime
+import feedparser
+import sys
+
+def parseArguments():
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--feed-path', dest='feed_path',
+                      help='Path or Url of the feed to search')
+  parser.add_argument('--title', dest='title', action='store_true',
+                      help='Patterns should be looked for in feed item\'s title')
+  parser.add_argument('--description', dest='description', action='store_true',
+                      help='Patterns should be looked for in feed item\'s description')
+  parser.add_argument('--ok-pattern', dest='ok_pattern_list', action='append',
+                      default=[],
+                      help='If this pattern is found, then promise succeeds')
+  parser.add_argument('--ko-pattern', dest='ko_pattern_list', action='append',
+                      default=[],
+                      help='If this pattern is found, then promise fails')
+  parser.add_argument('--time-buffer', dest='time_buffer', type=int,
+                      help='Time delta in seconds before the promise really succeeds or fails')
+  return parser.parse_args()
+
+def containsPattern(string, pattern_list):
+  for pattern in pattern_list:
+    if string.find(pattern) >= 0:
+      return True
+  return False
+
+def main():
+  option = parseArguments()
+  feed = feedparser.parse(option.feed_path)
+
+  if feed.bozo:
+    sys.exit('Feed malformed')
+
+  last_item = feed.entries[-1]
+  if option.title:
+    candidate_string = last_item.title
+  elif option.description:
+    candidate_string = last_item.description
+  else:
+    sys.exit('At least one in [--title|--description] should be provided')
+
+  publication_date = datetime.datetime(*last_item.published_parsed[:7])
+  publication_age = datetime.datetime.now() - publication_date
+  time_buffer = datetime.timedelta(seconds=option.time_buffer)
+
+  ok_pattern_found = containsPattern(candidate_string, option.ok_pattern_list)
+  ko_pattern_found = containsPattern(candidate_string, option.ko_pattern_list)
+
+  if ok_pattern_found and ko_pattern_found:
+    sys.exit('Both OK and KO patterns found: please check arguments')
+
+  # Expectations fulfilled
+  if ok_pattern_found:
+      sys.exit(0)
+
+  if ko_pattern_found:
+    sys.exit('KO pattern found')
+
+  if not ok_pattern_found:
+    if publication_age < time_buffer:
+      # We have to wait for buffer to expire
+      sys.exit(0)
+    else:
+      # If time-buffer is out, we are in stalled state
+      sys.exit('Stalled situation')
+
+  # If not ok, and not stalled, what can have possibly happen ?
+  sys.exit(1)
+
+if __name__ == '__main__':
+  main()
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