Sharing code between Firebase Functions and React - node.js

Question

I'm using Firebase functions with a React application. I have some non-trivial code that I don't want to duplicate, so I want to share it between the deployed functions and my React client. I've got this working locally in my React client (though I haven't tried deploying) - but I can't deploy my functions.
The first thing I tried was npm link. This worked locally, but the functions won't deploy (which makes sense, since this leaves no dependency in your package.json). Then I tried npm install ../shared/ - this looked promising because it did leave a dependency in package.json with a file: prefix - but Firebase still won't deploy with this (error below).
My project directory structure looks like this:
/ProjectDir
firebase.json
package.json (for the react app)
/src
* (react source files)
/functions
package.json (for firebase functions)
index.js
/shared
package.json (for the shared module)
index.js
My shared module package.json (extraneous details omitted):
{
"name": "myshared",
"scripts": {
},
"dependencies": {
},
"devDependencies": {
},
"engines": {
"node": "8"
},
"private": true,
"version": "0.0.1"
}
My firebase functions package.json (extraneous details omitted):
{
"name": "functions",
"scripts": {
},
"dependencies": {
"myshared": "file:../shared",
},
"devDependencies": {
},
"engines": {
"node": "8"
},
"private": true
}
When I try to deploy with:
firebase deploy --only functions
It's telling me it can't load the module:
Function failed on loading user code. Error message: Code in file index.js can't be loaded.
Did you list all required modules in the package.json dependencies?
And I don't think the issue is how I export/imported my code- but just in case:
The export:
exports.myFunc = () => { some code };
The import (functions/index.js)
const myFunc = require('myshared');
And in my react code:
import { myFunc } from 'myshared';
So far the searching I've done hasn't yielded anything that works. Someone did mention entering the shared module path in firebase.json, but I couldn't find any details (including in the firebase docs) that show what that would look like. Thanks for any tips to get this going.

Answer 1

I found a solution. I'm not sure if it's the only or even the best solution, but it seems to work for this scenario, and is easy. As Doug noted above, Firebase doesn't want to upload anything not in the functions directory. The solution was to simply make my shared module a subdirectory under functions (ie ./functions/shared/index.js). I can then import into my functions like a normal js file. However, my shared folder also has a package.json, for use as a dependency to the react app. I install it using:
npm install ./functions/shared
This creates a dependency in my react app, which seems to resolve correctly. I've created a production build without errors. I haven't deployed the react app yet, but I don't think this would be an issue.

Answer 2

Another solution is to create a symlink. In terminal, under /ProjectDir, execute:
ln -s shared functions/shared
cd functions
npm i ./shared