Make event attributes immutable (#1195)

Author: Eoin Noble

opentelemetry-sdk/CHANGELOG.md

@@ -10,6 +10,8 @@
   ([#1105](https://github.com/open-telemetry/opentelemetry-python/pull/1120))
 - Allow for Custom Trace and Span IDs Generation - `IdsGenerator` for TracerProvider
   ([#1153](https://github.com/open-telemetry/opentelemetry-python/pull/1153))
+- Event attributes are now immutable
+  ([#1195](https://github.com/open-telemetry/opentelemetry-python/pull/1195))
 - Renaming metrics Batcher to Processor
   ([#1203](https://github.com/open-telemetry/opentelemetry-python/pull/1203))
 - Protect access to Span implementation

opentelemetry-sdk/src/opentelemetry/sdk/trace/__init__.py

@@ -18,12 +18,11 @@
 import concurrent.futures
 import json
 import logging
-import random
 import threading
 import traceback
 from collections import OrderedDict
 from contextlib import contextmanager
-from types import TracebackType
+from types import MappingProxyType, TracebackType
 from typing import (
     Any,
     Callable,
@@ -340,6 +339,10 @@ def _filter_attribute_values(attributes: types.Attributes):
                 attributes.pop(attr_key)
 
 
+def _create_immutable_attributes(attributes):
+    return MappingProxyType(attributes.copy() if attributes else {})
+
+
 class Span(trace_api.Span):
     """See `opentelemetry.trace.Span`.
 
@@ -408,6 +411,10 @@ def __init__(
         if events:
             for event in events:
                 _filter_attribute_values(event.attributes)
+                # pylint: disable=protected-access
+                event._attributes = _create_immutable_attributes(
+                    event.attributes
+                )
                 self.events.append(event)
 
         if links is None:
@@ -566,8 +573,7 @@ def add_event(
         timestamp: Optional[int] = None,
     ) -> None:
         _filter_attribute_values(attributes)
-        if not attributes:
-            attributes = self._new_attributes()
+        attributes = _create_immutable_attributes(attributes)
         self._add_event(
             Event(
                 name=name,

opentelemetry-sdk/tests/trace/test_trace.py

@@ -590,7 +590,6 @@ def test_events(self):
             root.add_event("event0")
 
             # event name and attributes
-            now = time_ns()
             root.add_event(
                 "event1", {"name": "pluto", "some_bools": [True, False]}
             )
@@ -628,6 +627,30 @@ def test_events(self):
                 root.events[3].attributes, {"name": ("original_contents",)}
             )
 
+    def test_events_are_immutable(self):
+        event_properties = [
+            prop for prop in dir(trace.EventBase) if not prop.startswith("_")
+        ]
+
+        with self.tracer.start_as_current_span("root") as root:
+            root.add_event("event0", {"name": ["birthday"]})
+            event = root.events[0]
+
+            for prop in event_properties:
+                with self.assertRaises(AttributeError):
+                    setattr(event, prop, "something")
+
+    def test_event_attributes_are_immutable(self):
+        with self.tracer.start_as_current_span("root") as root:
+            root.add_event("event0", {"name": ["birthday"]})
+            event = root.events[0]
+
+            with self.assertRaises(TypeError):
+                event.attributes["name"][0] = "happy"
+
+            with self.assertRaises(TypeError):
+                event.attributes["name"] = "hello"
+
     def test_invalid_event_attributes(self):
         self.assertEqual(trace_api.get_current_span(), trace_api.INVALID_SPAN)