Azure Function - Python Runtime - Flex Consumption - unable to get env var

Question

I thought it would be pretty simple, but I seems as if I am missing something

import os

app = func.FunctionApp(http_auth_level=func.AuthLevel.ANONYMOUS)

#for testing only
@app.route(route="get_tested", methods=["POST"])
def get_tested(req: func.HttpRequest) -> func.HttpResponse:

    logging.info("Processing 'get_tested' request")
    VAR = os.environ['VAR_NAME']
    print(VAR)
    return VAR

at the moment all I am trying to achieve is to print the "VAR" but it just comes back as None

I have verified that secret is set in the "Environmental Variables" on the left-hand panel.

when I do the tests and invoke the https request from the function portal/ postman, I get a 500 error

Edit: added tag environmental-variables, changed env var name from "secret" to "VAR" and python var from "secret" to "VAR" to get rid of confusion. I am already using keyvault for actual secrets, 2, updated script and added more information

Julian K · Accepted Answer · 2025-08-06 17:12:56Z

0

Now, I'm more familiar with Synapse but if you are simply trying to get a secret, you may want to consider using Azure Key Vault for this. It's free until like a million requests per month, so no worries there unless you need to access your secret every 2 seconds. You can easily import it using the following code:

# make sure you have these libraries installed of course
from azure.identity import DefaultAzureCredential 
from azure.keyvault.secrets import SecretClient

key_vault_url = "https://vault_name.vault.azure.net/"
secret_name = "secret_name"

credential = DefaultAzureCredential()
client = SecretClient(vault_url=key_vault_url, credential=credential)

retrieved_secret = client.get_secret(secret_name)
print(retrieved_secret.value)

Key Vault stores you secret securely and allows for separate access control, since it is a resource by itself. Meaning, this also requires your Azure User (EntraID) to have the respective permissions, but that is fairly easy to do in Azure, if you are and Admin and are able to subscribe to new resources.

Let me know if this helps! Not the environment-variable solution you may be looking for but should get the job done as well.

EDIT:
I'm a dork, should read your code properly... try adding:

from dotenv import load_dotenv

load_dotenv()

underneath your "import os" line.

edited Aug 6 at 17:12

answered Aug 6 at 17:10

Julian K

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2 Comments

lookslikeanevo Aug 6 at 18:26

Thanks, I'm actually using KV for actual secrets already. I just used the word "secrets" as the env var label

lookslikeanevo Aug 7 at 1:15

load_dotenv() was my first try. actually have it in there as part of local testing.

pets485 · Accepted Answer · 2025-08-19 13:53:35Z

0

The code itself looks correct to me. If that’s returning None it could be due to your Python version. Azure's flex consumption plan does not fully support Python 3.13 yet.

Can you confirm what Python version your Function App is set to in Configuration → General settings? At the moment, Azure Functions officially supports Python 3.10, 3.11, and 3.12. If the app is configured to use 3.13, the runtime will not load any environment variables.

Reference: Azure Functions Flex Consumption plan hosting

answered Aug 19 at 13:53

pets485

11 bronze badge

1 Comment

user31339853 Aug 23 at 22:36

ran into the same issue... back to pyhton 3.12 and it works like charm.

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