[Bug] correlation-id of received Event Hub event is empty

[MihailV1989]

Expected Behavior

When a Azure Function is triggered by an Event Hub event, you get a azure.functions.EventHubEvent Class. This class has the attribute "metadata" - "read-only trigger metadata in a Python dictionary". From it I should be able to access the system and custom properties of the event, e.g. the Correlation ID.

Actual Behavior

When I print the content of the metadata, the "correlation-id" field is empty. I got only the Custom Property "somecustomproperty".

Steps to Reproduce

Create a simple Azure Function triggered by Event Hub as documented here. In the function body log the whole metadata like this:

logging.info(f"Whole event metadata: {myhub.metadata}")

You can use the Data Explorer from the Event Hub page in the Azure Portal to send a sample event. Just make sure that under "System Properties" the Correlation ID is not empty.

Relevant code being tried

import logging
import azure.functions as func

app = func.FunctionApp()

@app.function_name(name="EventHubTrigger1")
@app.event_hub_message_trigger(arg_name="myhub", 
                               event_hub_name="<EVENT_HUB_NAME>",
                               connection="<CONNECTION_SETTING>") 
def test_function(myhub: func.EventHubEvent):
    logging.info(f"Whole event metadata: {myhub.metadata}")

Relevant log output

{
    "SequenceNumber": 486099,
    "PartitionContext": {
        "IsCheckpointingAfterInvocation": True,
        "FullyQualifiedNamespace": "***",
        "EventHubName": "***",
        "ConsumerGroup": "local_func_debug",
        "PartitionId": "0"
    },
    "SystemProperties": {
        "message-id": {},
        "user-id": {
            "Length": 0,
            "IsEmpty": True
        },
        **"correlation-id": {},**
        "content-type": "text/plain",
        "x-opt-sequence-number-epoch": -1,
        "x-opt-sequence-number": 486099,
        "x-opt-offset": 1958513386000,
        "x-opt-enqueued-time": "2025-05-13T15:14:40.71+00:00",
        "SequenceNumber": 486099,
        "Offset": 1958513386000,
        "PartitionKey": None,
        "EnqueuedTimeUtc": "2025-05-13T15:14:40.71"
    },
    "TriggerPartitionContext": {
        "IsCheckpointingAfterInvocation": True,
        "FullyQualifiedNamespace": "***",
        "EventHubName": "***",
        "ConsumerGroup": "local_func_debug",
        "PartitionId": "0"
    },
    "EnqueuedTimeUtc": "2025-05-13T15:14:40.71",
    "Properties": {
        "somecustomproperty": "somevalue"
    },
    "Offset": 1958513386000
}

requirements.txt file

azure-functions>=1.20.0,<2.0.0

Where are you facing this problem?

Local - Core Tools

Additional Information

Using Python 3.11/3.12 in a Linux Function App with Runtime version ~4.

[hallvictoria]

Hi @MihailV1989, this looks to be the same issue as #931, so I will transfer to the extensions repo.

In late May, we will be announcing support for SDK-type bindings for EventHub, which will allow you to bind to the EventData object from azure-eventhub. That may help your scenario