Deploy Multiple full-stack React + Express applications with path routing on ELB - amazon-web-services

Question

I currently have four containerized React + Express applications (port 3001 exposed) sitting on four individual ECS instances with four different CNAMEs. They each sit behind their own nginx service as a reverse proxy.
Given that the number of applications may increase, I'm hoping to re-deploy this on ECS with an ELB, but I'm running into problems with the path routing. My goal is to have a system where <url_name>/service-1 will route traffic to the container referenced in service-1 and so on.
Currently, the services are all in a running state, but the routing provides a bunch of console errors saying the static js and css files produced by the react build command cannot be found at <url_name>/. Has anyone found a way to run multiple full-stack React + Express applications with path routing on ELB or a workaround of adding in an Nginx service or updating the React homepage to a fixed value?
# container_definition
[
{
"name": "service-1",
"image": "<image-name>:latest",
"cpu": 256,
"memory": 256,
"portMappings": [
{
"containerPort": 3001,
"hostPort": 3001
}
],
"essential": true
}
]
# rule.json
{
"ListenerArn": "placeholder",
"Conditions": [
{
"Field": "path-pattern",
"Values": [
"/service-1*"
]
}
],
"Priority": 1,
"Actions": [
{
"Type": "forward",
"TargetGroupArn": "placeholder"
}
]
}
# server.js
const express = require('express'),
path = require('path');
const createServer = function () {
const port = 3001;
// Create a new Express server
const app = express(),
subpath = express();
// Ensure every api route is prefixed by /api
app.use('/api', subpath);
// All routes related to access points
const users = require('./routes/users');
subpath.get('/users/:id', users.getUserById);
// serve up static assets, i.e. HTML, CSS, and JS from /build
app.use(express.static('build'));
if (process.env.NODE_ENV)
app.get('*', (req, res) => res.sendFile(path.join(__dirname + '/build/index.html')));
// Start the HTTP listener using the given port
return app.listen(port, () => console.log(`Express server (HTTP) listening on port ${port}`))
};
module.exports = createServer;