[Bug]: OpenMeter integration fails due to incorrect CloudEvent subject field format #7569
Description
What happened?
The openmeter integration doesn't work correctly, the cloudevent subject field transmitted by litellm is invalid and the openmeter server throws a status code 400.
The cloudEvent config on the openmeter end is configured correctly (as shown in the official openmeter docs), as demonstrated by the following test curl that runs successfully:
curl -X POST https://openmeter.cloud/api/v1/events \
-H 'Content-Type: application/cloudevents+json' \
-H 'Authorization: Bearer <OPENMETER_PLACEHOLDER_API_KEY>' \
--data-raw '
{
"specversion" : "1.0",
"type": "litellm_tokens",
"id": "3ed4f15f-8dcf-45cb-8ec3-0922f5a67ab7",
"time": "2025-01-05T10:15:57.783Z",
"source": "my-app",
"subject": "customer-1",
"data": {
"completion_tokens": "123",
"cost": "cost",
"model": "model",
"prompt_tokens": "prompt_tokens",
"total_tokens": "total_tokens"
}
}
'
The problem appears to be in the extraction of the user field inside the openmeter code:
litellm/litellm/integrations/openmeter.py
Line 68 in 9cfd7c7
where the user OpenAI spec field is extracted and used as the subject for the cloudevent event.
Thanks for the great project!
Relevant log output
litellm-1 | {"message": "LiteLLM.LoggingError: [Non-Blocking] Exception occurred while success logging Traceback (most recent call last):\n File \"/usr/local/lib/python3.13/site-packages/litellm/integrations/openmeter.py\", line 124, in async_log_success_event\n await self.async_http_handler.post(\n ...<3 lines>...\n )\n File \"/usr/local/lib/python3.13/site-packages/litellm/llms/custom_httpx/http_handler.py\", line 219, in post\n raise e\n File \"/usr/local/lib/python3.13/site-packages/litellm/llms/custom_httpx/http_handler.py\", line 177, in post\n response.raise_for_status()\n ~~~~~~~~~~~~~~~~~~~~~~~~~^^\n File \"/usr/local/lib/python3.13/site-packages/httpx/_models.py\", line 761, in raise_for_status\n raise HTTPStatusError(message, request=request, response=self)\nhttpx.HTTPStatusError: Client error '400 Bad Request' for url 'https://openmeter.cloud/api/v1/events'\nFor more information check: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/400\n\nDuring handling of the above exception, another exception occurred:\n\nTraceback (most recent call last):\n File \"/usr/local/lib/python3.13/site-packages/litellm/litellm_core_utils/litellm_logging.py\", line 1602, in async_success_handler\n await callback.async_log_success_event(\n ...<6 lines>...\n )\n File \"/usr/local/lib/python3.13/site-packages/litellm/integrations/openmeter.py\", line 130, in async_log_success_event\n raise Exception(f\"OpenMeter logging error: {e.response.text}\")\nException: OpenMeter logging error: {\"type\":\"about:blank\",\"title\":\"Bad Request\",\"status\":400,\"detail\":\"request body has an error: doesn't match schema #/components/schemas/Event: Error at \\\"/subject\\\": value must be a string\"}\n\n", "level": "ERROR", "timestamp": "2025-01-05T03:36:32.704192"}Are you a ML Ops Team?
No
What LiteLLM version are you on ?
v1.56.9
Twitter / LinkedIn details
No response