By devcshort
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
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Hi there,
Based on the output, it looks like that the DigitalOcean Load Balancer health checks are not reaching your application correctly, which is why it’s showing your droplets as “down”. Here are some potential issues and solutions:
-
Health check path and port: In your DigitalOcean Load Balancer configuration, your health check is set to
http://0.0.0.0:3000/health. The0.0.0.0should be replaced with the private IP of the droplet or simply/healthif the load balancer and the droplet are in the same VPC network. -
Check if the firewall is allowing incoming connections: Ensure that your firewall is configured to allow incoming connections to port 3000 (the port on which your Node.js application is running) from the IP address of the Load Balancer. This also applies to any security group rules if you’re using VPC networks.
-
Check if the application is running and accessible from the outside: You can SSH into your droplet and use a tool like
curlto test if your health check endpoint is accessible. Runcurl http://localhost:3000/healthto check this. -
Trust proxy setting: In Express.js,
app.set('trust proxy', true);tells the app to trust the headers set by the proxy (in this case, the load balancer). This is generally required when you want to access protocol (HTTP/HTTPS) or get the real client IP address in your application. -
Use a process manager: If you are running your application directly using
node app.js, it will stop as soon as the terminal session is closed. It’s recommended to use a process manager likepm2which will ensure that your app keeps running even after the terminal session is closed or the server is restarted. -
Use HTTPS for health checks: If your server is set to redirect all HTTP to HTTPS, then your health check also needs to be in HTTPS, not HTTP. Ensure your load balancer is setup with an SSL certificate (either from DigitalOcean or a custom one) and change the health check to
https://localhost:3000/health.
Best,
Bobby
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