Fixed when private_ips is empty (fixed #103)

examples/basic/main.tf

@@ -67,7 +67,7 @@ module "ec2" {
   ami           = data.aws_ami.amazon_linux.id
   instance_type = "c5.large"
   subnet_id     = tolist(data.aws_subnet_ids.all.ids)[0]
-  private_ip                  = ["123.0.0.1", "123.0.0.2"]
+  //  private_ips                 = ["172.31.32.5", "172.31.46.20"]
   vpc_security_group_ids      = [module.security_group.this_security_group_id]
   associate_public_ip_address = true
   placement_group             = aws_placement_group.web.id
@@ -95,6 +95,7 @@ module "ec2_with_t2_unlimited" {
   instance_type = "t2.micro"
   cpu_credits   = "unlimited"
   subnet_id     = tolist(data.aws_subnet_ids.all.ids)[0]
+  //  private_ip = "172.31.32.10"
   vpc_security_group_ids      = [module.security_group.this_security_group_id]
   associate_public_ip_address = true
 }

main.tf

@@ -24,10 +24,7 @@ resource "aws_instance" "this" {
   iam_instance_profile   = var.iam_instance_profile
 
   associate_public_ip_address = var.associate_public_ip_address
-  private_ip = element(
-    distinct(compact(concat([var.private_ip], var.private_ips))),
-    count.index,
-  )
+  private_ip                  = length(var.private_ips) > 0 ? element(var.private_ips, count.index) : var.private_ip
   ipv6_address_count          = var.ipv6_address_count
   ipv6_addresses              = var.ipv6_addresses
 
@@ -90,7 +87,6 @@ resource "aws_instance" "this" {
     # (eg, https://github.com/terraform-providers/terraform-provider-aws/issues/2036)
     # we have to ignore changes in the following arguments
     ignore_changes = [
-      private_ip,
       root_block_device,
       ebs_block_device,
     ]
@@ -113,10 +109,7 @@ resource "aws_instance" "this_t2" {
   iam_instance_profile   = var.iam_instance_profile
 
   associate_public_ip_address = var.associate_public_ip_address
-  private_ip = element(
-    distinct(compact(concat([var.private_ip], var.private_ips))),
-    count.index,
-  )
+  private_ip                  = length(var.private_ips) > 0 ? element(var.private_ips, count.index) : var.private_ip
   ipv6_address_count          = var.ipv6_address_count
   ipv6_addresses              = var.ipv6_addresses
 
@@ -183,7 +176,6 @@ resource "aws_instance" "this_t2" {
     # (eg, https://github.com/terraform-providers/terraform-provider-aws/issues/2036)
     # we have to ignore changes in the following arguments
     ignore_changes = [
-      private_ip,
       root_block_device,
       ebs_block_device,
     ]