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',
           'check-web-page-http-cache-hit = slapos.promise.check_web_page_http_cache_hit:main',
+          'check-feed-as-promise = slapos.checkfeedaspromise:main',
           'clouddestroy = slapos.cloudmgr.destroy:main',
           'cloudgetprivatekey = slapos.cloudmgr.getprivatekey:main',
           'cloudgetpubliciplist = slapos.cloudmgr.getpubliciplist:main',

slapos/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, to determine if the emitter process is in
+# a stalled state, in the case that no OK pattern has been found
+
+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,
+                      default=0,
+                      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 checkFeedAsPromise(feed, option):
+  feed = feedparser.parse(feed)
+
+  if feed.bozo:
+    return 'Feed malformed'
+
+  last_item = feed.entries[-1]
+  if option.title:
+    candidate_string = last_item.title
+  elif option.description:
+    candidate_string = last_item.description
+  else:
+    return '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:
+    return 'Both OK and KO patterns found: please check arguments'
+
+  # Expectations fulfilled
+  if ok_pattern_found:
+      return ''
+
+  if ko_pattern_found:
+    return 'KO pattern found'
+
+  if not ok_pattern_found:
+    if publication_age < time_buffer:
+      # We have to wait for buffer to expire
+      return ''
+    else:
+      # If time-buffer is out, we are in stalled state
+      return 'Stalled situation'
+
+  # If not ok, and not stalled, what can have possibly happen ?
+  return 'Something went wrong'
+
+
+def main():
+  option = parseArguments()
+  result = checkFeedAsPromise(option.feed_path, option)
+
+  if len(result) > 0:
+    sys.exit(result)
+  else:
+    sys.exit(0)
+
+
+if __name__ == '__main__':
+  main()

slapos/test/test_checkfeedaspromise.py

+import datetime
+import feedparser
+import time
+import unittest
+
+import PyRSS2Gen as RSS2
+
+from slapos.checkfeedaspromise import checkFeedAsPromise
+
+class Option(dict):
+    def __init__(self, **kw): 
+        self.__dict__.update(kw)
+    def __setitem__(i, y):
+        self.__dict__[i] = y
+
+class TestCheckFeedAsPromise(unittest.TestCase):
+  def getOptionObject(self, **kw):
+    """
+    Returns an object containing options as properties, to simulate a call
+    to the tested script
+    """
+    option = {
+      'title': False,
+      'description': False,
+      'time_buffer': 0,
+      'ok_pattern_list': [],
+      'ko_pattern_list': [],
+    }
+    option.update(kw)
+    return Option(**option)
+
+
+  def generateFeed(self, item_list):
+    return RSS2.RSS2(
+      title="Feed Title",
+      link="http://exemple.com",
+      description="Feed Description",
+      items=[RSS2.RSSItem(**item) for item in item_list]
+    ).to_xml()
+
+
+  def generateOKFeed(self, extra_item_list=None):
+    item_list = [{
+      'title': 'Doing Something',
+      'description': 'work work work',
+      'pubDate': datetime.datetime.now(),
+      }, {
+      'title': 'Something Finished: OK',
+      'description': 'OK FINISHED DONE BASTA',
+      'pubDate': datetime.datetime.now(),
+    }]
+    if isinstance(extra_item_list, list):
+      item_list.append(extra_item_list)
+    return self.generateFeed(item_list)
+
+
+  def generateKOFeed(self, extra_item_list=None):
+    item_list = [{
+      'title': 'Doing Something',
+      'description': 'work work work',
+      'pubDate': datetime.datetime.now(),
+      }, {
+      'title': 'Something Finished: Error',
+      'description': 'FAILURE oops Arghh',
+      'pubDate': datetime.datetime.now(),
+    }]
+    if isinstance(extra_item_list, list):
+      item_list.extend(extra_item_list)
+    return self.generateFeed(item_list)
+
+
+  def test_ifOKFoundNoErrorReturned(self):
+    option = self.getOptionObject()
+    option.title = True
+    feed = self.generateOKFeed()
+
+    option.ok_pattern_list = ['OK']
+    self.assertEquals(checkFeedAsPromise(feed, option), "")
+    option.title, option.description  = False, True
+    option.ok_pattern_list = ['DONE', 'OK']
+    self.assertEquals(checkFeedAsPromise(feed, option), "")
+
+
+  def test_ifKOFoundErrorReturned(self):
+    option = self.getOptionObject()
+    option.title = True
+    feed = self.generateKOFeed()
+
+    option.ko_pattern_list = ['Error']
+    self.assertNotEquals(checkFeedAsPromise(feed, option), "")
+    option.title, option.description  = False, True
+    option.ko_pattern_list = ['FAILURE', 'Error']
+    self.assertNotEquals(checkFeedAsPromise(feed, option), "")
+
+
+  def test_ifNoOKPatternFoundErrorIsRaised(self):
+    option = self.getOptionObject()
+    option.title = True
+    feed = self.generateKOFeed()
+
+    # If no time buffer, then not OK is always wrong
+    option.ok_pattern_list = ['OK']
+    self.assertNotEquals(len(checkFeedAsPromise(feed, option)), 0)
+
+    # if time buffer, then not OK is wrong only after buffer expires
+    extra_item = {
+      'title': 'Something is Starting',
+      'description': 'Very long operation, but should last less than 1h',
+      'pubDate': datetime.datetime.now() - datetime.timedelta(seconds=3600),
+    }
+    feed = self.generateKOFeed([extra_item,])
+    option.time_buffer = 4000
+    # buffer longer than last item's age
+    self.assertEquals(checkFeedAsPromise(feed, option), "")
+
+    # shorter buffer, we want to raise an error
+    option.time_buffer = 1800
+    self.assertNotEquals(len(checkFeedAsPromise(feed, option)), 0)
+
+
+if __name__ == '__main__':
+  unittest.main()