How can we avoid existing EBS volumes from being deleted? - amazon-web-services

Question

I'm using Terraform 1.1.3 with aws provider 3.75.2 to create TF code for the existing 2-node infra. The code snippet is like below:
module:
resource "aws_ebs_volume" "backend-logs" {
count = var.create_ebs_log_volumes ? var.backend_nodes_qty : 0
availability_zone = element(data.aws_subnet.backend.*.availability_zone, count.index)
size = var.volume_log_size
type = var.ebs_volume_type
encrypted = var.ebs_enable_encryption
kms_key_id = var.ebs_encryption_key_id
}
resource "aws_volume_attachment" "backend-logs" {
count = var.backend_nodes_qty
device_name = "/dev/sdf"
volume_id = element(module.xyz.backend_ebs_volume_log_ids, count.index)
instance_id = element(module.xyz.backend_instance_ids, count.index)
}
and I've imported the instance/volume/attachment resources successfully.
terraform import module.xyz.aws_ebs_volume.backend-logs[0] vol-0123456789abcedf0
terraform import module.xyz.aws_ebs_volume.backend-logs[1] vol-0123456789abcedf1
terraform import aws_volume_attachment.backend-logs[0] /dev/sdf:vol-0123456789abcedf0:i-0123456789abcedf0
terraform import aws_volume_attachment.backend-logs[1] /dev/sdf:vol-0123456789abcedf1:i-0123456789abcedf1
When I run terraform plan, the plan tells me that the volumes are going to be destroyed. How can we avoid that? thanks
# aws_volume_attachment.backend-logs[0] must be replaced
-/+ resource "aws_volume_attachment" "backend-logs" {
~ id = "vai-1993905001" -> (known after apply)
~ volume_id = "vol-0123456789abcedf0" -> (known after apply) # forces replacement
# (2 unchanged attributes hidden)
}
# aws_volume_attachment.backend-logs[1] must be replaced
-/+ resource "aws_volume_attachment" "backend-logs" {
~ id = "vai-1955292002" -> (known after apply)
~ volume_id = "vol-0123456789abcedf1" -> (known after apply) # forces replacement
# (2 unchanged attributes hidden)
}
# module.xyz.aws_ebs_volume.backend-logs[0] must be replaced
-/+ resource "aws_ebs_volume" "backend-logs" {
~ arn = "arn:aws:ec2:us-west-2:1234567890:volume/vol-0123456789abcedf0" -> (known after apply)
~ availability_zone = "us-west-2a" -> (known after apply) # forces replacement
~ id = "vol-0123456789abcedf0" -> (known after apply)
~ iops = 150 -> (known after apply)
+ kms_key_id = (known after apply)
- multi_attach_enabled = false -> null
+ snapshot_id = (known after apply)
~ throughput = 0 -> (known after apply)
# (3 unchanged attributes hidden)
}
# module.xyz.aws_ebs_volume.backend-logs[1] must be replaced
-/+ resource "aws_ebs_volume" "backend-logs" {
~ arn = "arn:aws:ec2:us-west-2:1234567890:volume/vol-0123456789abcedf1" -> (known after apply)
~ availability_zone = "us-west-2b" -> (known after apply) # forces replacement
~ id = "vol-0123456789abcedf1" -> (known after apply)
~ iops = 150 -> (known after apply)
+ kms_key_id = (known after apply)
- multi_attach_enabled = false -> null
+ snapshot_id = (known after apply)
~ throughput = 0 -> (known after apply)
# (3 unchanged attributes hidden)
}

Answer 1

It seems that the issue relates to AZ stuff. You can try the workaround by adding these lines in aws_instance block.
lifecycle {
ignore_changes = [ availability_zone ]
}