Azure Functions NodeJS Express app throws Unable to determine function entry point error

Question

I am trying to create a simple hello world azure functions app using nodejs and express. But, i am getting the following error:

Exception while executing function: Functions.httpexpressapp. mscorlib: Unable to determine function entry point. If multiple functions are exported, you must indicate the entry point, either by naming it 'run' or 'index', or by naming it explicitly via the 'entryPoint' metadata property.

Here is my code:

function.json

 {
  "bindings": [
    {
      "authLevel": "anonymous",
      "type": "httpTrigger",
      "direction": "in",
      "name": "req"
    },
    {
      "type": "http",
      "direction": "out",
      "name": "res"
    }
  ],
  "entryPoint": "index",
  "disabled": false
}

index.js:

const express = require('express')
const app = express()

app.get('/', (req, res) => res.send('Express JS Hello World App!!!'))

package.json:

{
  "name": "httpexpressapp",
  "version": "1.0.0",
  "description": "sample app",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "john doe",
  "license": "ISC",
  "dependencies": {
    "express": "^4.16.3"
  }
}

Then, i have a node_modules directory under the function app

Any help is appreciated. Thanks in advance!

@Mikhail it works on my local machine if it's a non function app, only difference is that i had an app.listen() in the index.js, i am new to both node and functions, so not sure what i am doing wrong. Do you know what i am doing wrong? — aazeem
– aazeem, Commented Jul 3, 2018 at 21:42
Functions expect you to export a function with specific signature. Follow the guide for your first function. — Mikhail Shilkov
– Mikhail Shilkov, Commented Jul 3, 2018 at 21:51

Connor McMahon · Accepted Answer · 2018-07-03 21:52:52Z

5

The Azure Functions platform is rather opinionated because of its ability to do things like bindings and Triggers. Functions coded in Node in Azure Functions need to be of the form.

module.exports = function(context) {
    // function logic goes here :)
};

You can find some JavaScript tips for Azure Functions here. It looks like you are trying to do a simple HTTP-trigger function. Looking at your example, you would want something like this.

module.exports = function(context, req) {
    context.res = {
        // status defaults to 200 */
        body: "Express JS Hello World App!!!"
    };
    context.done();
};

Note that Azure Functions will be handling the routing of your HTTP requests, so you wouldn't likely want to use Express.js.

answered Jul 3, 2018 at 21:52

Connor McMahon

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Comments

Sohaib · Accepted Answer · 2020-12-30 05:15:37Z

1

Even if you want to use the Express with the Azure function you can go for this Azure AWS serverless Express

package. Its very useful.

answered Dec 30, 2020 at 5:15

Sohaib

81311 silver badges15 bronze badges

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