How can I set up a Load Balancer for my Expressjs based application?

I’ve set up a load balancer that is picking up my droplets by tag, however, they are always showing as a status of “down”.

I am pointing the load balancer directly to my nodejs APIs, without Nginx or anything sitting in front. I also have an endpoint set up called “/health” which simply returns a status of 200, and the load balancer set to use that endpoint.

Below is the configuration for my Expressjs server.

app.set('trust proxy', true);

app.use(helmet());
app.use(cors());
app.use(passport.initialize());
app.get('/health', (req, res) => res.sendStatus(200));
app.use('/api', routes);

app.listen(PORT, () => {
    console.log(
        chalk.yellow(`Listening on *:${PORT}`)
    );
});

My load balancer configuration is as follows

Forwarding rules 
HTTP on port 80  HTTP on port 3000
HTTPS on port 443  HTTP on port 3000

Algorithm
Least Connections

Health checks 
http://0.0.0.0:3000/health

Sticky sessions 
Off

SSL
Redirect HTTP to HTTPS

Proxy Protocol
Enabled