Made max header length configurable for cloudevents. (#4)

* Made max header length configurable for cloudevents.
* Updated to 4k as the default header length.

Author: pantierra

eoapi_notifier/outputs/cloudevents.py

@@ -28,6 +28,7 @@ class CloudEventsConfig(BasePluginConfig):
     timeout: float = 30.0
     max_retries: int = 3
     retry_backoff: float = 1.0
+    max_header_length: int = 4096
 
     @field_validator("endpoint")
     @classmethod
@@ -53,6 +54,7 @@ def get_sample_config(cls) -> dict[str, Any]:
             "timeout": 30.0,
             "max_retries": 3,
             "retry_backoff": 1.0,
+            "max_header_length": 4096,
         }
 
     @classmethod
@@ -191,6 +193,16 @@ async def send_event(self, event: NotificationEvent) -> bool:
             )
             return False
 
+    def _truncate_header(self, value: str | None) -> str | None:
+        """Truncate header value to max_header_length if needed."""
+        if not value:
+            return value
+        if len(value.encode("utf-8")) <= self.config.max_header_length:
+            return value
+        # Truncate to byte limit, ensuring valid UTF-8
+        truncated = value.encode("utf-8")[: self.config.max_header_length]
+        return truncated.decode("utf-8", errors="ignore")
+
     def _convert_to_cloudevent(self, event: NotificationEvent) -> CloudEvent:
         """Convert NotificationEvent to CloudEvent."""
         # Use config values which now include environment overrides
@@ -211,11 +223,15 @@ def _convert_to_cloudevent(self, event: NotificationEvent) -> CloudEvent:
 
         # Add subject if item_id exists
         if event.item_id:
-            attributes["subject"] = event.item_id
+            truncated_subject = self._truncate_header(event.item_id)
+            if truncated_subject:
+                attributes["subject"] = truncated_subject
 
         # Add collection attribute
         if event.collection:
-            attributes["collection"] = event.collection
+            truncated_collection = self._truncate_header(event.collection)
+            if truncated_collection:
+                attributes["collection"] = truncated_collection
 
         # Event data payload
         data = {

examples/config.yaml

@@ -61,6 +61,7 @@ outputs:
       # Optional: HTTP settings
       # timeout: 30.0                       # CLOUDEVENTS_TIMEOUT
       # max_retries: 3                      # CLOUDEVENTS_MAX_RETRIES
+      # max_header_length: 4096             # CLOUDEVENTS_MAX_HEADER_LENGTH
 
 # Example with multiple sources and outputs
 # sources:

tests/test_cloudevents_output.py

@@ -34,6 +34,7 @@ def test_default_configuration(self) -> None:
         assert config.event_type == "org.eoapi.stac"
         assert config.timeout == 30.0
         assert config.max_retries == 3
+        assert config.max_header_length == 4096
 
     def test_endpoint_validation_error(self) -> None:
         """Test endpoint validation."""
@@ -198,6 +199,62 @@ def test_convert_to_cloudevent(
         assert cloud_event["subject"] == "test-item"
         assert cloud_event["collection"] == "test-collection"
 
+    def test_truncate_header(self, adapter: CloudEventsAdapter) -> None:
+        """Test header value truncation."""
+        # Short string should not be truncated
+        short = "short-string"
+        assert adapter._truncate_header(short) == short
+
+        # None should remain None
+        assert adapter._truncate_header(None) is None
+
+        # Long string should be truncated to max_header_length bytes
+        long_string = "a" * 3000
+        truncated = adapter._truncate_header(long_string)
+        assert truncated is not None
+        assert len(truncated.encode("utf-8")) <= adapter.config.max_header_length
+        assert len(truncated) <= adapter.config.max_header_length
+
+        # UTF-8 multi-byte characters should be handled correctly
+        unicode_string = "测试" * 1000  # Chinese characters (3 bytes each)
+        truncated_unicode = adapter._truncate_header(unicode_string)
+        assert truncated_unicode is not None
+        assert (
+            len(truncated_unicode.encode("utf-8")) <= adapter.config.max_header_length
+        )
+        # Should not break in the middle of a character
+        assert truncated_unicode.encode("utf-8").decode("utf-8") == truncated_unicode
+
+    def test_convert_to_cloudevent_with_long_headers(
+        self, config: CloudEventsConfig
+    ) -> None:
+        """Test CloudEvent conversion with long header values."""
+        config.max_header_length = 50  # Small limit for testing
+        adapter = CloudEventsAdapter(config)
+
+        # Create event with long item_id and collection
+        event = NotificationEvent(
+            source="/test/source",
+            type="test.type",
+            operation="INSERT",
+            collection="a-very-long-collection-name-that-exceeds-the-limit",
+            item_id="a-very-long-item-id-that-also-exceeds-the-configured-limit",
+        )
+
+        cloud_event = adapter._convert_to_cloudevent(event)
+
+        # Check that long values are truncated in headers
+        assert "subject" in cloud_event
+        assert "collection" in cloud_event
+        assert len(cloud_event["subject"].encode("utf-8")) <= config.max_header_length
+        assert (
+            len(cloud_event["collection"].encode("utf-8")) <= config.max_header_length
+        )
+
+        # Original values should still be in data payload
+        assert cloud_event.data["item_id"] == event.item_id
+        assert cloud_event.data["collection"] == event.collection
+
     def test_operation_mapping(self, adapter: CloudEventsAdapter) -> None:
         """Test operation to event type mapping."""
         test_cases = [