ELB is generally configured with 3 subnets in 3 AZs
Actual behavior
Only a single subnet in a single AZ was configured
Events as seen from ECS:
The individual tasks were terminating with a SIGTERM: 7 error. That alone didn't tell me much, but the ECS event logs showed the real issue:
(instance i-038db12314955a4d7) is unhealthy in elb l0-chunnelprod0108-Product5c5b5 due to (reason Instance is in the EC2 Availability Zone for which LoadBalancer is not configured to route traffic to.)
Expected behavior
ELB is generally configured with 3 subnets in 3 AZs
Actual behavior
Only a single subnet in a single AZ was configured
Events as seen from ECS: The individual tasks were terminating with a SIGTERM: 7 error. That alone didn't tell me much, but the ECS event logs showed the real issue:
(instance i-038db12314955a4d7) is unhealthy in elb l0-chunnelprod0108-Product5c5b5 due to (reason Instance is in the EC2 Availability Zone for which LoadBalancer is not configured to route traffic to.)
Steps to reproduce the behavior
🤷♀️ first time i have seen this.