Natgateway doesn't have failover at availability zone level #16
Description
NatGateway is not a regional service when we create an environment using cloudlift, It creates a single nat gateway in one availability zone and uses the same route table for two subnets created in different az's.
so incase the az which host the single nat goes down, the entire VPC goes down and the instances in 2nd az will not be able to access the internet because nat gateway is down.
from amazon documentation:
If you have resources in multiple Availability Zones and they share one NAT gateway, and if the NAT gateway’s Availability Zone is down, resources in the other Availability Zones lose internet access. To create an Availability Zone-independent architecture, create a NAT gateway in each Availability Zone and configure your routing to ensure that resources use the NAT gateway in the same Availability Zone
.
https://docs.aws.amazon.com/vpc/latest/userguide/vpc-nat-gateway.html