How to share code between Netlify lambda functions

Question

I have 3 separate functions each in their own folders. All of them make use of a Twilio client and Apollo Client for dealing with SMS and GraphQL server respectively.

Rather than having all the code to instantiate each client (get keys from env etc.) in each file, can it be put somewhere and required in?

I've tried putting the code into a .js file in the top level functions/ folder and requiring it in the function code as below and this works fine locally on netlify dev but errors with Module not found '../twilioClient' when the function is called in live environment.

/functions
  apolloClient.js
  twilioClient.js
  package.json - specifying deps used by above files
  /auth
    auth.js - require('../apolloClient')
    ...
  /trails
    trails.js - require('../twilioClient') etc.
    ...

Answer 1

I had success with this approach.

Short answer:

Create a utils file in your functions folder and require it in your function files.

Long answer:

My netlify.toml file looks like this:

[build] 
    functions = "./functions"

And functions folder:

/functions
 function-1.js
 function-2.js
 utils.js

And utils.js:

exports.helloWorld = () => {
    console.log('hello world')
}

And function-1.js:

const {helloWorld} = require('./utils')

exports.handler = async (event) => {
  helloWorld()
}

To test it:

Run netlify dev or deploy it. Your Functions logs or terminal should say 'hello world'.

My netlify site deploys from GitHub.