fix: address invalid count bug (#118)

Author: RoseSecurity

main.tf

@@ -1,6 +1,8 @@
 locals {
   enabled         = module.this.enabled
-  create_password = local.enabled && length(var.master_password) == 0
+  create_password = local.enabled && var.master_password == null
+
+  master_password = local.create_password ? one(random_password.password[*].result) : var.master_password
 }
 
 resource "aws_security_group" "default" {
@@ -56,7 +58,7 @@ resource "aws_security_group_rule" "ingress_cidr_blocks" {
 }
 
 resource "random_password" "password" {
-  count   = local.enabled && local.create_password ? 1 : 0
+  count   = local.create_password ? 1 : 0
   length  = 16
   special = false
 }
@@ -65,7 +67,7 @@ resource "aws_docdb_cluster" "default" {
   count                           = local.enabled ? 1 : 0
   cluster_identifier              = module.this.id
   master_username                 = var.master_username
-  master_password                 = var.master_password != "" ? var.master_password : random_password.password[0].result
+  master_password                 = local.master_password
   backup_retention_period         = var.retention_period
   preferred_backup_window         = var.preferred_backup_window
   preferred_maintenance_window    = var.preferred_maintenance_window
@@ -168,7 +170,7 @@ module "ssm_write_db_password" {
   parameter_write = [
     {
       name        = format("%s%s", var.ssm_parameter_path_prefix, module.this.id)
-      value       = var.master_password != "" ? var.master_password : random_password.password[0].result
+      value       = local.master_password
       type        = "SecureString"
       description = "Master password for ${module.this.id} DocumentDB cluster"
     }

variables.tf

@@ -95,7 +95,7 @@ variable "master_username" {
 
 variable "master_password" {
   type        = string
-  default     = ""
+  default     = null
   description = "(Required unless a snapshot_identifier is provided) Password for the master DB user. Note that this may show up in logs, and it will be stored in the state file. Please refer to the DocumentDB Naming Constraints"
 }