[Azure function] using env var in function.json

Question

[Azure function] using env var in function.json

Dy Zapra, Keisha Marie 30

Sample function.json

{
  "bindings": [
    {
      "queueName": "test-queue",
      "name": "message",
      "type": "serviceBusTrigger",
      "direction": "in",
      "isSessionsEnabled": true
    }
  ],
  "scriptFile": "handler.mjs"
}

is there a way to grab the "isSessionsEnabled" value from the env var/local.settings.json? This is for node.

1 answer

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Answer 1

Sedat SALMAN 14,190 MVP

you can follow this article to get the values from local.settings.json

https://damienaicheh.github.io/azure/azure-functions/dotnet/2022/05/10/use-settings-json-azure-function-en.html

Dy Zapra, Keisha Marie 30 Reputation points

2023-05-30T11:18:09.3266667+00:00

Oh I forgot to specify but this is for node and we want the variable used inside function.json
Sedat SALMAN 14,190 Reputation points MVP

2023-05-30T21:50:20.8166667+00:00

as I know in your case it is better to use process.env to get environmental variables

but you need to check the correct file according to your deployment environment (cloud or local)

please follow this one

https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference-node?pivots=nodejs-model-v4&tabs=javascript%2Cwindows-setting-the-node-version
Dy Zapra, Keisha Marie 30 Reputation points

2023-06-01T10:14:01.9733333+00:00

Great! I see from that document that it would be trivial to do what I want for v4.x but how about for v3.x where bindings are in the function.json?
Sedat SALMAN 14,190 Reputation points MVP

2023-06-01T18:33:25.49+00:00

https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference-node?pivots=nodejs-model-v3&tabs=javascript%2Cwindows-setting-the-node-version

in this link you can select 4.x or 3.x to check the differences

also check this link for examples

https://stackoverflow.com/questions/37877609/azure-functions-can-environment-variables-be-used-in-function-json

For Azure Functions v3.x, using environment variables in function.json is already supported. This is particularly useful for handling connection strings, since you don't want those checked in with your source code. You can use an app setting name for the connection value, and it will be auto-resolved. Most of the binding properties support the %% resolution syntax, allowing you to store the actual values in app settings for both security and configurability
Dy Zapra, Keisha Marie 30 Reputation points

2023-06-01T19:51:01.7+00:00

The %% was the first thing we tried but it always gave us a "was not recognized as a valid Boolean" error even when the value in local.settings.json was a boolean.

Does isSessionsEnabled require a specific binding style?
Dy Zapra, Keisha Marie 30 Reputation points

2023-06-07T07:55:06.83+00:00

Nudging on this. Our fallback right now is to use v4 instead of having a function.json.
Henrique Donati 0 Reputation points

2025-07-24T13:39:20.9033333+00:00

I had a very similar issue as you but using Python V1. I needed a slightly different config on the environment it was being published to. Python V2 function apps have no issues, but the legacy app I was tasked with maintaining was using V1.

I ended up using GitHub secrets and replacing the values on the function.json via github actions using the sed command prior to the deployment.

This may be a route for you if you want the isSessionsEnabled set based on the deployment slot and/or environment.

I know this is old, but I just had this issue earlier this week. I thought other people could benefit in the future from this answer :D

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[Azure function] using env var in function.json

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