Why do Azure functions report success if HTTP 500 is returned?

Donald Carnegie 6

Using Python 3.9 and function runtime 3.

The following code results in a HTTP 500 being returned, but the portal reports this as success. Why? Surely this should be a failure?

   except:  
               logging.exception("The error message i want to appear in my logs")  
               return func.HttpResponse(  
                   f"The error message I want the user to see.",  
                   status_code=500,  
               )

1 answer

Stanislav Zhelyazkov 21,411 Reputation points MVP

2021-08-11T11:57:42.93+00:00

Hi,
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2 people found this answer helpful.
Donald Carnegie 6 Reputation points

2021-08-11T12:05:08.73+00:00

Okay, thanks. I'm not sure this is the right thing to do but I suppose it is what it is.

So if I want the execution to be marked as a failure I have to raise an exception and not return a HTTP response - I can work with this. Is there any way I can raise an exception and have the exception message returned to the user in the response? The following code results in an empty response body:

except: logging.exception("The error message i want to appear in my logs") raise Exception("The error message I want the user to see")

Ideally I would like the function execution to be marked as a failure, but also pass a user friendly error message back in the response.

Stanislav Zhelyazkov 21,411 Reputation points MVP

2021-08-12T07:50:42.053+00:00

Hi,
The status show that the execution of the function was successful no matter that the end result of the HTTP error. When the execution is successful and the status code is something like 500 the end user who invokes the API will get the correct HTTP error code. So if it is 500 it will be failure. You will get "Error" (instead of Success) only when the function encounters some unhandled exception. With unhandled exception the user will not get any error as well. What you should strive is to handle any error as possible. I am not expert on Python but you can use the standard logging there. I believe if you use the error() method you will probably achieve what you want. Keep in mind that logs are logged to Application Insights and you can use Kusto query language to track the details of these. What you see in monitor that is actually data from requests table and Success column is based on success column in request table. The value can be either true or false. Unhandled exceptions and messages from error() method should go to exceptions table.
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