Merge pull request #59 from isovalent/pr/fgiloux/azs

feat: Make it possible to select availability zones

README.md

@@ -47,17 +47,18 @@ An opinionated Terraform module that can be used to create and manage an VPC in
 | Name | Description | Type | Default | Required |
 |------|-------------|------|---------|:--------:|
 | <a name="input_additional_private_subnet_tags"></a> [additional\_private\_subnet\_tags](#input\_additional\_private\_subnet\_tags) | Additional tags for the private subnets | `map(string)` | `{}` | no |
-| <a name="input_additional_private_subnets"></a> [additional\_private\_subnets](#input\_additional\_private\_subnets) | Additional private subnets to create. | <pre>list(object({<br>    availability_zone = string<br>    cidr              = string<br>    tags              = map(string)<br>  }))</pre> | `[]` | no |
+| <a name="input_additional_private_subnets"></a> [additional\_private\_subnets](#input\_additional\_private\_subnets) | Additional private subnets to create. | <pre>list(object({<br/>    availability_zone = string<br/>    cidr              = string<br/>    tags              = map(string)<br/>  }))</pre> | `[]` | no |
 | <a name="input_additional_public_subnet_tags"></a> [additional\_public\_subnet\_tags](#input\_additional\_public\_subnet\_tags) | Additional tags for the public subnets | `map(string)` | `{}` | no |
-| <a name="input_additional_public_subnets"></a> [additional\_public\_subnets](#input\_additional\_public\_subnets) | Additional public subnets to create. | <pre>list(object({<br>    availability_zone = string<br>    cidr              = string<br>    tags              = map(string)<br>  }))</pre> | `[]` | no |
+| <a name="input_additional_public_subnets"></a> [additional\_public\_subnets](#input\_additional\_public\_subnets) | Additional public subnets to create. | <pre>list(object({<br/>    availability_zone = string<br/>    cidr              = string<br/>    tags              = map(string)<br/>  }))</pre> | `[]` | no |
+| <a name="input_availability_zones"></a> [availability\_zones](#input\_availability\_zones) | List of availability zone names that subnets can get deployed into.<br/>  If not provided, defaults to all AZs for the region. | `list(string)` | `[]` | no |
 | <a name="input_bastion_host_ami_id"></a> [bastion\_host\_ami\_id](#input\_bastion\_host\_ami\_id) | The ID of the AIM to use for the instance. Setting this will ignore `bastion_host_ami_name_filter` and `bastion_host_ami_owners`. | `string` | `null` | no |
 | <a name="input_bastion_host_ami_name_filter"></a> [bastion\_host\_ami\_name\_filter](#input\_bastion\_host\_ami\_name\_filter) | The AMI filter to use for the bastion host's AMI. | `string` | `"amzn2-ami-hvm-2.*-x86_64-ebs"` | no |
-| <a name="input_bastion_host_ami_owners"></a> [bastion\_host\_ami\_owners](#input\_bastion\_host\_ami\_owners) | The list of owners used to select the AMI. | `list(string)` | <pre>[<br>  "amazon"<br>]</pre> | no |
+| <a name="input_bastion_host_ami_owners"></a> [bastion\_host\_ami\_owners](#input\_bastion\_host\_ami\_owners) | The list of owners used to select the AMI. | `list(string)` | <pre>[<br/>  "amazon"<br/>]</pre> | no |
 | <a name="input_bastion_host_assign_public_ip"></a> [bastion\_host\_assign\_public\_ip](#input\_bastion\_host\_assign\_public\_ip) | Whether to assign a public IP address to the bastion host. | `bool` | `false` | no |
 | <a name="input_bastion_host_enabled"></a> [bastion\_host\_enabled](#input\_bastion\_host\_enabled) | Whether to create an EC2 instance in the VPC that can be used as a bastion host. | `bool` | `false` | no |
 | <a name="input_bastion_host_extra_security_groups"></a> [bastion\_host\_extra\_security\_groups](#input\_bastion\_host\_extra\_security\_groups) | A list of extra security groups to associate with the bastion host. | `list(string)` | `[]` | no |
 | <a name="input_bastion_host_instance_type"></a> [bastion\_host\_instance\_type](#input\_bastion\_host\_instance\_type) | The instance type to use for the bastion host. | `string` | `"t2.micro"` | no |
-| <a name="input_bastion_host_security_group_rules"></a> [bastion\_host\_security\_group\_rules](#input\_bastion\_host\_security\_group\_rules) | A list of security group rules to apply to the bastion host. | `list(any)` | <pre>[<br>  {<br>    "cidr_blocks": [<br>      "0.0.0.0/0"<br>    ],<br>    "description": "Allow all outbound traffic",<br>    "from_port": 0,<br>    "protocol": -1,<br>    "to_port": 0,<br>    "type": "egress"<br>  },<br>  {<br>    "cidr_blocks": [<br>      "0.0.0.0/0"<br>    ],<br>    "description": "Allow all inbound to SSH",<br>    "from_port": 22,<br>    "protocol": "tcp",<br>    "to_port": 22,<br>    "type": "ingress"<br>  }<br>]</pre> | no |
+| <a name="input_bastion_host_security_group_rules"></a> [bastion\_host\_security\_group\_rules](#input\_bastion\_host\_security\_group\_rules) | A list of security group rules to apply to the bastion host. | `list(any)` | <pre>[<br/>  {<br/>    "cidr_blocks": [<br/>      "0.0.0.0/0"<br/>    ],<br/>    "description": "Allow all outbound traffic",<br/>    "from_port": 0,<br/>    "protocol": -1,<br/>    "to_port": 0,<br/>    "type": "egress"<br/>  },<br/>  {<br/>    "cidr_blocks": [<br/>      "0.0.0.0/0"<br/>    ],<br/>    "description": "Allow all inbound to SSH",<br/>    "from_port": 22,<br/>    "protocol": "tcp",<br/>    "to_port": 22,<br/>    "type": "ingress"<br/>  }<br/>]</pre> | no |
 | <a name="input_bastion_host_ssh_public_key"></a> [bastion\_host\_ssh\_public\_key](#input\_bastion\_host\_ssh\_public\_key) | If specified, will be used as the public SSH key for the bastion host. | `string` | `""` | no |
 | <a name="input_bastion_host_user_data"></a> [bastion\_host\_user\_data](#input\_bastion\_host\_user\_data) | The user data to use for the bastion host. | `list(string)` | `[]` | no |
 | <a name="input_bastion_host_user_data_base64"></a> [bastion\_host\_user\_data\_base64](#input\_bastion\_host\_user\_data\_base64) | The user data to use for the bastion host, base64 encoded. | `string` | `""` | no |

locals.tf

@@ -1,3 +1,4 @@
 locals {
   bastion_host_key_pair_name = "${var.name}-bastion"
+  availability_zones         = length(var.availability_zones) > 0 ? var.availability_zones : data.aws_availability_zones.available.names
 }

main.tf

@@ -22,16 +22,16 @@ module "vpc" {
   source  = "terraform-aws-modules/vpc/aws"
   version = "5.0.0"
 
-  azs                     = data.aws_availability_zones.available.names // Use all availability zones.
-  cidr                    = var.cidr                                    // Use the CIDR specified as a variable.
-  enable_dns_hostnames    = true                                        // Enable DNS hostnames (required by EKS).
-  enable_nat_gateway      = true                                        // Enable NAT gateway to enable outbound internet traffic from instances in a private subnet.
-  name                    = var.name                                    // Use the name specified as a variable.
-  one_nat_gateway_per_az  = false                                       // Use a single NAT gateway as that's the simplest and also all we need.
-  secondary_cidr_blocks   = var.secondary_cidr_blocks                   // Define secondary CIDR blocks.
-  single_nat_gateway      = true                                        // Use a single NAT gateway as that's the simplest and also all we need.
-  tags                    = var.tags                                    // Use the tags specified as a variable.
-  map_public_ip_on_launch = var.map_public_ip_on_launch                 // Map public IP on launch for instances in public subnets.
+  azs                     = local.availability_zones    // Use selected availability zones.
+  cidr                    = var.cidr                    // Use the CIDR specified as a variable.
+  enable_dns_hostnames    = true                        // Enable DNS hostnames (required by EKS).
+  enable_nat_gateway      = true                        // Enable NAT gateway to enable outbound internet traffic from instances in a private subnet.
+  name                    = var.name                    // Use the name specified as a variable.
+  one_nat_gateway_per_az  = false                       // Use a single NAT gateway as that's the simplest and also all we need.
+  secondary_cidr_blocks   = var.secondary_cidr_blocks   // Define secondary CIDR blocks.
+  single_nat_gateway      = true                        // Use a single NAT gateway as that's the simplest and also all we need.
+  tags                    = var.tags                    // Use the tags specified as a variable.
+  map_public_ip_on_launch = var.map_public_ip_on_launch // Map public IP on launch for instances in public subnets.
 
   enable_ipv6                                    = var.enable_ipv6 // this will provide Amazon-provided IPv6 CIDR block which is a /56 block
   public_subnet_assign_ipv6_address_on_creation  = var.enable_ipv6 // this will help the EC2 to get the IPV6 address when it boots
@@ -40,7 +40,7 @@ module "vpc" {
   // Create one private subnet per AZ (e.g. "10.1.0.0/24", "10.1.1.0/24", "10.1.2.0/24", ...).
   // This could surely have been made differently (possibly even sourced from a variable), but it suffices for the time being.
   private_subnets = [
-    for i, v in data.aws_availability_zones.available.names :
+    for i, v in local.availability_zones :
     cidrsubnet(var.cidr, 8, i)
   ]
   // Tag the private subnets adequately.
@@ -56,7 +56,7 @@ module "vpc" {
   // Create one public subnet per AZ (e.g. "10.1.100.0/24", "10.1.101.0/24", "10.1.102.0/24", ...).
   // This could surely have been made differently (possibly even sourced from a variable), but it suffices for the time being.
   public_subnets = [
-    for i, v in data.aws_availability_zones.available.names :
+    for i, v in local.availability_zones :
     cidrsubnet(var.cidr, 8, 100 + i)
   ]
   // Tag the public subnets adequately.
@@ -69,11 +69,11 @@ module "vpc" {
   )
   //This is needed when enabling the IPV6 but will not hurt when the IPV6 is not enabled.
   private_subnet_ipv6_prefixes = [
-    for i, v in data.aws_availability_zones.available.names :
+    for i, v in local.availability_zones :
     i
   ]
   public_subnet_ipv6_prefixes = [
-    for i, v in data.aws_availability_zones.available.names :
+    for i, v in local.availability_zones :
     10 + i
   ]
 

variables.tf

@@ -12,6 +12,16 @@
 //  See the License for the specific language governing permissions and
 //  limitations under the License.
 
+variable "availability_zones" {
+  # Usage: -var 'availability_zones=["us-east-1a"]'
+  description = <<-EOT
+    List of availability zone names that subnets can get deployed into.
+      If not provided, defaults to all AZs for the region.
+  EOT
+  type        = list(string)
+  default     = []
+}
+
 variable "additional_private_subnet_tags" {
   description = "Additional tags for the private subnets"
   type        = map(string)
@@ -168,4 +178,4 @@ variable "map_public_ip_on_launch" {
   default     = false
   description = "Whether to map public IPs on launch."
   type        = bool
-}
+}