reporting: Using a uuid to enforce uniqueness on the KVP keys.

The KVPs currently being emitted to the .kvp_pool file can have
duplicate keys which is wrong since these keys should be unique.
The situation can occur if for example one azure function
called twice or more and this function is reporting telemetry
through the use of KVPs. Any KVP consumer can get confused by
the duplicate keys and a race condition can and have occurred.

2 files changed, 23 insertions, 3 deletions

diff --git a/cloudinit/reporting/handlers.py b/cloudinit/reporting/handlers.py
index 10165aec..6605e795 100755
--- a/cloudinit/reporting/handlers.py
+++ b/cloudinit/reporting/handlers.py
@@ -1,6 +1,7 @@
 # This file is part of cloud-init. See LICENSE file for license information.
 
 import abc
+import uuid
 import fcntl
 import json
 import six
@@ -201,10 +202,11 @@ class HyperVKvpReportingHandler(ReportingHandler):
     def _event_key(self, event):
         """
         the event key format is:
-        CLOUD_INIT|<incarnation number>|<event_type>|<event_name>
+        CLOUD_INIT|<incarnation number>|<event_type>|<event_name>|<time>
         """
-        return u"{0}|{1}|{2}".format(self.event_key_prefix,
-                                     event.event_type, event.name)
+        return u"{0}|{1}|{2}|{3}".format(self.event_key_prefix,
+                                         event.event_type, event.name,
+                                         uuid.uuid4())
 
     def _encode_kvp_item(self, key, value):
         data = (struct.pack("%ds%ds" % (
diff --git a/tests/unittests/test_reporting_hyperv.py b/tests/unittests/test_reporting_hyperv.py
index 640895a4..3582cf0b 100644
--- a/tests/unittests/test_reporting_hyperv.py
+++ b/tests/unittests/test_reporting_hyperv.py
@@ -191,3 +191,21 @@ class TextKvpReporter(CiTestCase):
 
         if "test_diagnostic" not in evt_msg:
             raise AssertionError("missing expected diagnostic message")
+
+    def test_unique_kvp_key(self):
+        reporter = HyperVKvpReportingHandler(kvp_file_path=self.tmp_file_path)
+        evt1 = events.ReportingEvent(
+            "event_type", 'event_message',
+            "event_description")
+        reporter.publish_event(evt1)
+
+        evt2 = events.ReportingEvent(
+            "event_type", 'event_message',
+            "event_description", timestamp=evt1.timestamp + 1)
+        reporter.publish_event(evt2)
+
+        reporter.q.join()
+        kvps = list(reporter._iterate_kvps(0))
+        self.assertEqual(2, len(kvps))
+        self.assertNotEqual(kvps[0]["key"], kvps[1]["key"],
+                            "duplicate keys for KVP entries")