Terraform AWS AZ error - manually specify AZ?

Question

I'm fairly new to terraform and when creating AWS infrastructure I use the following to fetch the 'available' availability zones for my region (us-east-1) where I'm trying to create an EKS cluster.

data "aws_availability_zones" "available" {}

However when I run a 'terraform apply', it generates the following error because us-east-1a is at capacity.

aws_eks_cluster.demo: error creating EKS Cluster (test-cluster): 
UnsupportedAvailabilityZoneException: Cannot create cluster 'test-cluster' because us-east-1a, the targeted availability zone, does not 
currently have sufficient capacity to support the cluster. Retry and 
choose from these availability zones: us-east-1b, us-east-1c, us-east-1d

Is there any way I can get terraform to handle this automatically or specify that I only want to use 1b,1c,1d etc.

EDIT:

I've realised this is tied with where I create my subnets, which I do using this line:

 availability_zone = "${data.aws_availability_zones.available.names[count.index]}"

So I assume I somehow need to skip us-east-1a by doing something here?

Thanks in advance.

Answer 1

If anyone else has this issue, here's how I got around it.

Specify a variable with the availability zones you want to target

variable "zones" {
  default = ["us-east-1b", "us-east-1c", "us-east-1d"]
}

When creating your subnets, use this line

availability_zone = "${var.zones[count.index]}"

Answer 2

You could use AWS ClI for consult availability zones:

aws ec2 describe-availability-zones

With this result you could prepare a script to take the first result.

Answer 3

I know this is an old question but I came across this same issue, and solved it in a different way. Rather than hardcoding the availability zones like the accepted answer, I think it is better to filter out those availability zones that do not support EKS. This approach makes it easier to move to a new region because the data is coming from aws, and not a hardcoded list.

https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/availability_zones#exclude_names

data "aws_availability_zones" "available" {
    # List of availability zones that do not support EKS
    exclude_names = ["us-east-1e"]
}