I'm trying to manually set up a load balanced environment using EC2. My instances are reachable via SSH and ping. However, as soon as I put them inside a load balancer, the instances are not able to pass the load balancer's health checks.

  • I've tried following the Troubleshooting Elastic Load Balancing guide. Connecting to any instance via telnet from another instance inside the same VPC does not work.
  • Executing telnet localhost 25 inside an instance seems to work.
  • The instances run Amazon Linux.
  • The health check happens via TCP to port 80.
  • The load balancer and the instances are in the same security group.
  • I've already loosened up all security group settings and allowed communication via all ports, all members of all groups are able to ssh / ping each other.
  • The problems appear right after launch, no matter if I've set up the instances with the software I want them to run or left them untouched.

What else should I try? Thanks!

  • Do you have your web server running on your instance? Can you confirm that the instance responds with status code 200 on port 80 if you connect to it directly using a web browser or curl? Jul 14 '15 at 16:01
  • Thanks. I got it working by directing the health check to port 22.
    – zerodot
    Jul 14 '15 at 20:02

Got it working by directing the health check to port 22.

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