Azure 函数/事件中心和 Blob 输出绑定。 如何有效地保存消息（Python）

Question

I'm stuck with Azure Functions connected to Event Hub and I don't find that the documentation is very relevant for this.

If I take the small python example to make a loop for existing events in order to save them manually to a blob storage:

from typing import List
import logging
import azure.functions as func


def main(events: List[func.EventHubEvent], outputBlob: func.Out[func.InputStream]):
    for event in events:
        logging.info('Python EventHub trigger processed an event: %s', event.get_body().decode('utf-8'))
        outputBlob.set(event.get_body().decode('utf-8')) # Save to storage.

and for the function.json:

"bindings": [ ..., 
{
  "type": "blob",
  "direction": "out",
  "name": "outputBlob",
  "path": "outcontainer/{rand-guid}",
  "connection": "storage_STORAGE"
}

It works... but not correctly: if 3 messages are in the events, the first and the third are saved... but never the second. Any way to improve this, and to save each event with a name depending of the content of the message, or something else by providing the filename depending of some value of the event and managed in the loop by example?

Thanks,

Answer 1

Using storage output binding does cause such a problem, you can use storage SDK as an alternative solution, please refer to the following code:

Code:

from typing import List
import logging, time
import azure.functions as func
import os, uuid
from azure.storage.blob import BlobServiceClient, BlobClient, ContainerClient, __version__
import tempfile


def main(events: List[func.EventHubEvent]):
    connect_str = '<your-storage-connection-string>'
    blob_service_client = BlobServiceClient.from_connection_string(connect_str)
    container_name = '<your-container-name>'
    container_client = blob_service_client.get_container_client(container_name)
    for event in events:
        logging.info('Python EventHub trigger processed an event: %s', event.get_body().decode('utf-8'))

        temp_path = tempfile.gettempdir()

        # Create a file in the local data directory to upload and download
        local_file_name = str(uuid.uuid4()) + ".txt"
        upload_file_path = os.path.join(temp_path, local_file_name)

        # Write text to the file
        file = open(upload_file_path, 'w')
        file.write(event.get_body().decode('utf-8'))
        file.close()

        # Create a blob client using the local file name as the name for the blob
        blob_client = blob_service_client.get_blob_client(container=container_name, blob=local_file_name)

        print("\nUploading to Azure Storage as blob:\n\t" + local_file_name)

        # Upload the created file
        with open(upload_file_path, "rb") as data:
            blob_client.upload_blob(data)

Function.json:

{
  "scriptFile": "__init__.py",
  "bindings": [
    {
      "type": "eventHubTrigger",
      "name": "events",
      "direction": "in",
      "eventHubName": "frankhub",
      "connection": "frankeventhub_RootManageSharedAccessKey_EVENTHUB",
      "cardinality": "many",
      "consumerGroup": "$default",
      "dataType": "binary"
    }
  ]
}

You can refer to the following tutorial:

https://docs.microsoft.com/en-us/azure/storage/blobs/storage-quickstart-blobs-python