Cannot find module in azure function written in typescript

Question

I have deployed a simple azure function written in typescript. And I keep getting this error after I deploy it. FailureException: Worker was unable to load function xyz: 'Cannot find module 'lodash'Require stack:- C:\home\site\wwwroot\dist\xyz\index.js

This is how my function.json file looks

    {
  "bindings": [
    {
      "name": "myTimer",
      "type": "timerTrigger",
      "direction": "in",
      "schedule": "0 0 10 * * *"
    }
  ],
  "scriptFile": "../dist/xyz/index.js"
}

And this is how my package.json file looks

{
  "name": "xyz",
  "version": "1.0.0",
  "description": "",
  "scripts": {
    "build": "tsc",
    "build:production": "npm run prestart && npm prune --production",
    "watch": "tsc --w",
    "prestart": "npm run build",
    "start": "func start",
    "test": "echo \"No tests yet...\""
  },
  "dependencies": {
    "@azure/functions": "^3.0.0",
    "@azure/identity": "^2.0.4",
    "@azure/keyvault-secrets": "^4.4.0",
    "@types/node": "^18.7.18",
    "axios": "^0.21.1",
    "lodash": "^4.17.21",
    "moment": "2.18.1",
    "pg-promise": "^10.10.1",
    "tslib": "^2.4.0",
    "typescript": "^4.0.0"
  },
  "devDependencies": {
    "@azure/functions": "^3.0.0",
    "@azure/identity": "^2.0.4",
    "@azure/keyvault-secrets": "^4.4.0",
    "@types/node": "^18.7.18",
    "axios": "^0.21.1",
    "azure-cli": "^0.10.20",
    "lodash": "^4.17.21",
    "pg-promise": "^10.9.5",
    "tslib": "^2.4.0",
    "typescript": "^4.0.0"
  }
}

And this is how I used it in index.ts file.

declare var require: any;
import { AzureFunction, Context } from '@azure/functions';
import {
  differenceWith, forEach, get, groupBy, isEqual, keys, map,
  set, size
} from 'lodash';
import * as moment from 'moment';
import * as pgPromise from 'pg-promise';
const axios = require('axios');
const pgp = pgPromise({});

I have tried multiple fixes from StackOverflow, but I still keep getting this error. Am I missing something here? Thanks.

Answer 1

I have observed that in your package. Json file, you have included the packages in both dependencies and devdependencies . Instead, you have to mention the packages in dependencies only.

To achieve that, you can use npm install <package-name> --save in Terminal. This will install the package in dependencies in package. Json file.

Hence you can avoid mentioning the packages in devdependencies .

Here is the steps and code I followed to create sample Azure function written in Typescript:

1. function. Json :

{
  "bindings": [
    {
      "name": "myTimer",
      "type": "timerTrigger",
      "direction": "in",
      "schedule": "0 0 10 * * *"
    }
  ],
  "scriptFile": "../dist/kpreddy/index.js"
}

2. Package.json :

{
  "name": "kpproject",
  "version": "1.0.0",
  "description": "",
  "scripts": {
    "build": "tsc",
    "watch": "tsc -w",
    "prestart": "npm run build",
    "start": "func start",
    "test": "echo \"No tests yet...\""
  },
  "dependencies": {
    "axios": "^0.27.2",
    "azure-cli": "^0.10.20",
    "lodash": "^4.17.21",
    "moment": "^2.29.4",
    "pg-promise": "^10.12.0",
    "tslib": "^2.4.0"
  },
  "devDependencies": {
    "@azure/functions": "^2.0.0",
    "@types/node": "14.x",
    "typescript": "^4.0.0"
  }
}

3. Index.ts:

declare var require: any;
import { AzureFunction, Context } from '@azure/functions';
import {
  differenceWith, forEach, get, groupBy, isEqual, keys, map,
  set, size
} from 'lodash';
import * as moment from 'moment';
import * as pgPromise from 'pg-promise';
const axios = require('axios');
const pgp = pgPromise({});

const timerTrigger: AzureFunction = async function (context: Context, myTimer: any): Promise<void> {
  var timeStamp = new Date().toISOString();
  
if (myTimer.isPastDue)
  {
      context.log('Timer function is running late!');
  }
  context.log('Timer trigger function ran!', timeStamp);   
};

export default timerTrigger;

4. Run the project with the below command in the Terminal:

• npm install
• npm start

Output:

5. Executed a local function from the workspace as mentioned in the snippet:

Output:

6. Deployed local function[kpreddy] to the Azure function [Kpravallika]:

After clicking on Deploy to function app, select Azure subscription and Azure function app. Then a pop will display to deploy to azure:

Output:

7. After the deployment,the local function has been deployed to the Azure function: