Version bump, Style guide, dns records updates optional, and input validation

data.linode_domain.this.tf

@@ -1,3 +1,4 @@
 data "linode_domain" "this" {
+  count  = var.create_dns_record ? 1 : 0
   domain = var.domain_name
 }

output.domain_records.tf

@@ -0,0 +1,7 @@
+output "domain_records" {
+  description = "The DNS records created for the instance, if create_dns_record is true."
+  value = {
+    ipv4 = try(linode_domain_record.this_ipv4[0], null)
+    ipv6 = try(linode_domain_record.this_ipv6[0], null)
+  }
+}

output.fqdn.tf

@@ -0,0 +1,4 @@
+output "fqdn" {
+  description = "The fully qualified domain name of the Linode instance."
+  value       = "${var.host_name}.${var.domain_name}"
+}

output.instance.tf

@@ -1,3 +1,4 @@
 output "instance" {
-  value = linode_instance.this
+  description = "The entire linode_instance.this resource."
+  value       = linode_instance.this
 }

resource.linode_domain_record.this_ipv4.tf

@@ -1,5 +1,6 @@
 resource "linode_domain_record" "this_ipv4" {
-  domain_id   = data.linode_domain.this.id
+  count       = var.create_dns_record ? 1 : 0
+  domain_id   = data.linode_domain.this[0].id
   name        = var.host_name
   record_type = "A"
   target      = linode_instance.this.ip_address

resource.linode_domain_record.this_ipv6.tf

@@ -1,5 +1,6 @@
 resource "linode_domain_record" "this_ipv6" {
-  domain_id   = data.linode_domain.this.id
+  count       = var.create_dns_record ? 1 : 0
+  domain_id   = data.linode_domain.this[0].id
   name        = var.host_name
   record_type = "AAAA"
   target      = element(split("/", linode_instance.this.ipv6), 0)

resource.linode_instance.this.tf

@@ -2,11 +2,17 @@ resource "linode_instance" "this" {
   authorized_keys  = var.authorized_keys
   backups_enabled  = var.backups_enabled
   booted           = var.booted
-  label            = "${var.host_name}.${var.domain_name}"
   image            = var.image
+  label            = "${var.host_name}.${var.domain_name}"
   private_ip       = var.private_ip
+  region           = var.region
   tags             = var.tags
   type             = var.type
-  region           = var.region
   watchdog_enabled = var.watchdog_enabled
+
+  lifecycle {
+    ignore_changes = [
+      image,
+    ]
+  }
 }

terraform.tf

@@ -2,7 +2,7 @@ terraform {
   required_providers {
     linode = {
       source  = "linode/linode"
-      version = ">= 4.2.0"
+      version = ">= 4.3.0"
     }
   }
   required_version = ">= 1.11.5"

variable.authorized_keys.tf

@@ -1,4 +1,10 @@
 variable "authorized_keys" {
-  default = []
+  default     = []
-  type    = list(string)
+  description = "A list of SSH public keys to deploy for the root user on the newly created Linode instance."
+  type        = list(string)
+
+  validation {
+    condition     = alltrue([for key in var.authorized_keys : can(regex("^(ssh-rsa|ssh-ed25519|ecdsa-sha2-nistp256|ssh-dss)", key))]) || length(var.authorized_keys) == 0
+    error_message = "All authorized keys must be valid SSH public keys starting with ssh-rsa, ssh-ed25519, ecdsa-sha2-nistp256, or ssh-dss."
+  }
 }

variable.backups_enabled.tf

@@ -1,4 +1,5 @@
 variable "backups_enabled" {
-  default = true
+  default     = true
-  type    = bool
+  description = "If this field is set to true, the created Linode will automatically be enrolled in the Linode Backup service."
+  type        = bool
 }

variable.booted.tf

@@ -1,4 +1,5 @@
 variable "booted" {
-  default = true
+  default     = true
-  type    = bool
+  description = "If true, then the instance is kept or converted into a running state."
+  type        = bool
 }

variable.create_dns_record.tf

@@ -0,0 +1,5 @@
+variable "create_dns_record" {
+  default     = true
+  description = "If true, the module will look up the domain_name and create A and AAAA records for the instance."
+  type        = bool
+}

variable.domain_name.tf

@@ -1,4 +1,10 @@
 variable "domain_name" {
-  default = "example.com"
+  default     = "example.com"
-  type    = string
+  description = "The domain name for the Linode instance and domain records."
+  type        = string
+
+  validation {
+    condition     = can(regex("^[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}$", var.domain_name))
+    error_message = "The domain name must be a valid fully-qualified domain name (e.g., example.com)."
+  }
 }

variable.host_name.tf

@@ -1,4 +1,10 @@
 variable "host_name" {
-  default = "hello-world"
+  default     = "hello-world"
-  type    = string
+  description = "The host name for the Linode instance."
+  type        = string
+
+  validation {
+    condition     = can(regex("^[a-zA-Z0-9-]+$", var.host_name))
+    error_message = "The host name can only contain alphanumeric characters and hyphens."
+  }
 }

variable.image.tf

@@ -1,4 +1,10 @@
 variable "image" {
-  default = "linode/fedora38"
+  default     = "linode/fedora44"
-  type    = string
+  description = "An Image ID to deploy the Disk from."
+  type        = string
+
+  validation {
+    condition     = can(regex("^[a-zA-Z0-9-]+/[a-zA-Z0-9.-]+$", var.image))
+    error_message = "The image must be a valid Linode image ID (e.g., linode/fedora44)."
+  }
 }

variable.private_ip.tf

@@ -1,4 +1,5 @@
 variable "private_ip" {
-  default = true
+  default     = true
-  type    = bool
+  description = "If true, the created Linode will have private networking enabled."
+  type        = bool
 }

variable.region.tf

@@ -1,4 +1,10 @@
 variable "region" {
-  default = "us-central"
+  default     = "us-central"
-  type    = string
+  description = "The region where the Linode will be located."
+  type        = string
+
+  validation {
+    condition     = can(regex("^[a-z]{2}-[a-z]+(-[a-z]+)?$", var.region))
+    error_message = "The region must be a valid Linode region format (e.g., us-central, ap-south)."
+  }
 }

variable.tags.tf

@@ -1,4 +1,10 @@
 variable "tags" {
-  default = []
+  default     = []
-  type    = list(string)
+  description = "A list of tags applied to this object."
+  type        = list(string)
+
+  validation {
+    condition     = alltrue([for t in var.tags : can(regex("^[a-zA-Z0-9-_]+$", t))]) || length(var.tags) == 0
+    error_message = "Tags must only contain alphanumeric characters, hyphens, and underscores."
+  }
 }

variable.type.tf

@@ -1,4 +1,10 @@
 variable "type" {
-  default = "g6-nanode-1"
+  default     = "g6-nanode-1"
-  type    = string
+  description = "The Linode type defines the pricing, CPU, disk, and RAM specs of the instance."
+  type        = string
+
+  validation {
+    condition     = can(regex("^g[0-9]+-[a-zA-Z0-9-]+$", var.type))
+    error_message = "The type must be a valid Linode instance type (e.g., g6-nanode-1, g6-standard-2)."
+  }
 }

variable.watchdog_enabled.tf

@@ -1,4 +1,5 @@
 variable "watchdog_enabled" {
-  default = true
+  default     = true
-  type    = bool
+  description = "The watchdog, named Lassie, is a Shutdown Watchdog that monitors your Linode and will reboot it if it powers off unexpectedly."
+  type        = bool
 }