Getting an ALB to map port 80 to port 3000 on a node server

Question

The node server is running on port 3000 and has a react front end and an express backend. I am trying to use an AWS ALB so that I can get port 80 requests to be served by the node server on port 3000. I am not running nginx or apache or any other reverse proxy service.

The ec2 and ALB are in the same VPC and subnet, ports 80 and 3000 are open on the alb and ec2. I can surf to the URL on port 3000 but the health checks, set to / and port 3000, fail and I cannot surf to the URL on port 80.

How do I make the health checks work and is there anything else I am missing that would stop me from surfing to the URL on port 80?

Answer 1

You cannot check the website on port 80 because the instance has been removed by the load balancer due to health check. You should be able to access once the health check is fixed.

Fixing the health check

Method 1 make sure :3000/ returns status code 200 if you have defined the health check so

Method 2 change the health check to TCP and port 3000 temporarily, it should fix the healthcheck. Please wait for the instances to become healthy. You should be able to browse the website through port 80 after that. Change the url back to your desired health check url once you get everything else working.

troubleshoot Checklist

• EC2 instance accepts port 80 traffic from application load balancer
• Application load balancer port 80 is open
• Application load balancer health check URL is configured correctly