Cannot Connect to Dockerized Express HTTPS Server - node.js

Question

I'm trying to serve my app over HTTPS so that I can use a service worker with my React app.
To do this, I added https.createServer() to my Express startup script
#!/usr/bin/env node
/**
* Module dependencies.
*/
var app = require('../app');
var debug = require('debug')('robotapp:server');
var http = require('http');
var fs = require('fs');
var https = require('https');
/**
* Get port from environment and store in Express.
*/
var port = normalizePort(process.env.PORT || '8000');
app.set('port', port);
console.log('Listening on localhost:', port);
/**
* Create HTTP server.
*/
var server = http.createServer(app);
/**
* Add HTTPS server
*/
if (process.env.NODE_ENV === 'prod') {
https
.createServer(
{
key: fs.readFileSync('sslcerts/server.key', 'utf8'),
cert: fs.readFileSync('sslcerts/server.pem', 'utf8')
},
app
)
.listen(443, function() {
console.log('HTTPS listening on PORT 443');
});
}
/**
* Listen on provided port, on all network interfaces.
*/
server.listen(port);
server.on('error', onError);
server.on('listening', onListening);
/**
* Normalize a port into a number, string, or false.
*/
function normalizePort(val) {
var port = parseInt(val, 10);
if (isNaN(port)) {
// named pipe
return val;
}
if (port >= 0) {
// port number
return port;
}
return false;
}
/**
* Event listener for HTTP server "error" event.
*/
function onError(error) {
if (error.syscall !== 'listen') {
throw error;
}
var bind = typeof port === 'string' ? 'Pipe ' + port : 'Port ' + port;
// handle specific listen errors with friendly messages
switch (error.code) {
case 'EACCES':
console.error(bind + ' requires elevated privileges');
process.exit(1);
break;
case 'EADDRINUSE':
console.error(bind + ' is already in use');
process.exit(1);
break;
default:
throw error;
}
}
/**
* Event listener for HTTP server "listening" event.
*/
function onListening() {
var addr = server.address();
var bind = typeof addr === 'string' ? 'pipe ' + addr : 'port ' + addr.port;
debug('Listening on ' + bind);
}
When I build the Docker container and start the app, both the HTTP and HTTPS server start up (I can see the "Listening on localhost:8000" and "HTTPS listening on PORT 443" messages). I can successfully access the HTTP version of my app on PORT 8000, but when I go to access PORT 443 on my server I get a "This site cannot be reached" error.
At first I thought maybe I mapped my container ports wrong, but I checked and nothing seems out of ordinary
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
16d0013eec8a robotapp:2.1 "npm start" 4 seconds ago Up 3 seconds 0.0.0.0:443->443/tcp, 0.0.0.0:8000->8000/tcp silly_tesla
If anyone has any suggestions as to what I'm doing wrong, please let me know :)