Malformed ISO timestamps in cosmosdb input binding

[sebastianneubauer]

Investigative information

• Timestamp: 2023-10-12 20:48:19.689
• Invocation ID: 973c894ee4ea126f36f3a7f27edcc6de
• Region: West Europe

Repro steps

In a python azure function I have this comos db input binding

@app.function_name(name="UpdateChart")
@app.schedule(schedule="0 */5 * * * *", 
              arg_name="mytimer",
              run_on_startup=True)
@app.cosmos_db_input(arg_name="cosmos", 
                     database_name="particle-photon-db2",
                     container_name="weather",
                     sqlQuery="SELECT TOP 4500 * FROM c WHERE c.published_at > '2020-10-06T07:45:16.081Z' AND c.event='weather-data-v1' ORDER BY c.published_at DESC",
                     connection="MyCosmosDBConnectionString")
@app.blob_output(arg_name="outputblob",
                path="weather-app-container/chart_new.html",
                connection="MyStorageConnectionString")
def update_chart(mytimer: func.TimerRequest, cosmos: func.DocumentList, outputblob: func.Out[str]):
    dflist = []

    for i, item in enumerate(cosmos):
        # Append each item as a dictionary to list
        dict_item = dict(item['data'])
        logging.info(item['published_at'])
        dict_item['published_at'] = item['published_at']
        dflist.append(dict_item)

    df = pd.DataFrame.from_records(dflist)

    df['published_at'] = pd.to_datetime(df['published_at'])
...

Expected behavior

This worked in V1 of the azure functions just fine

Actual behavior

In V2 of azure functions with this hosts.json

{
  "version": "2.0",
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle",
    "version": "[4.0.0, 5.0.0)"
  },
  "extensions": {
      "cosmosDB": {
          "connectionMode": "Gateway"
      }
  }
}

it breaks for some data with the following exception:

Result: Failure 
Exception: ValueError: time data "2023-10-10T20:40:16Z" doesn't match format "%Y-%m-%dT%H:%M:%S.%f%z", at position 1429. You might want to try: - passing `format` if your strings have a consistent format; - passing `format='ISO8601'` if your strings are all ISO8601 but not necessarily in exactly the same format; - passing `format='mixed'`, and the format will be inferred for each element individually. You might want to use `dayfirst` alongside this. 
Stack:
 File "/azure-functions-host/workers/python/3.10/LINUX/X64/azure_functions_worker/dispatcher.py", line 479, in _handle__invocation_request call_result = await self._loop.run_in_executor( 
 File "/usr/local/lib/python3.10/concurrent/futures/thread.py", line 58, in run result = self.fn(*self.args, **self.kwargs) 
 File "/azure-functions-host/workers/python/3.10/LINUX/X64/azure_functions_worker/dispatcher.py", line 752, in _run_sync_func return ExtensionManager.get_sync_invocation_wrapper(context, 
 File "/azure-functions-host/workers/python/3.10/LINUX/X64/azure_functions_worker/extension.py", line 215, in _raw_invocation_wrapper result = function(**args) 
 File "/home/site/wwwroot/function_app.py", line 35, in update_chart df['published_at'] = pd.to_datetime(df['published_at']) 
 File "/home/site/wwwroot/.python_packages/lib/site-packages/pandas/core/tools/datetimes.py", line 1112, in to_datetime values = convert_listlike(arg._values, format) 
 File "/home/site/wwwroot/.python_packages/lib/site-packages/pandas/core/tools/datetimes.py", line 488, in _convert_listlike_datetimes return _array_strptime_with_fallback(arg, name, utc, format, exact, errors) 
 File "/home/site/wwwroot/.python_packages/lib/site-packages/pandas/core/tools/datetimes.py", line 519, in _array_strptime_with_fallback result, timezones = array_strptime(arg, fmt, exact=exact, errors=errors, utc=utc) 
 File "strptime.pyx", line 534, in pandas._libs.tslibs.strptime.array_strptime 
 File "strptime.pyx", line 355, in pandas._libs.tslibs.strptime.array_strptime

And indeed, after some debugging, I confirmed, that the timestamps in 'published_at' are malformed. Example: "2023-10-10T20:40:16Z" is wrong, when looking at the cosmos db data, there the timestamp string is: "2023-10-10T20:40:16.000Z". Note the missing trailing ".000" before the Z. I also confirmed, that all trailing 0 before the Z are stripped.

I could not find a way my code could introduce this bug. It most likely is introduced in the binding.

Summary: "2023-10-10T20:40:16Z" in 'published_at' handed into my azure function is wrong and should be "2023-10-10T20:40:16.000Z"

Known workarounds

I could to some evil string magic (fill up missing 0 before the Z), but I would rather not do it.

[bhagyshricompany]

Thanks for informing will check update this.plz share the func app name also

[sebastianneubauer]

app name is "UpdateChart", but I don't think that is relevant, you should be reproducible rather easy, just check any ISO timestamp in the results of an cosmosdb input binding. BTW: I just saw, the same is happening in the logs in the portal as well, so putting this into any function:

logging.info("2023-10-10T20:40:16.000Z")

results in this output in the azure function monitoring log:

"2023-10-15T20:10:01Z"