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.
telnet localhost 25inside 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!