From 1598212959b8aea004080901a0ea39ec2906d8bf Mon Sep 17 00:00:00 2001
From: Nam Nguyen <nam.nguyen@indebted.co>
Date: Sat, 9 Nov 2024 21:42:58 +1000
Subject: [PATCH] fix: ignore `tags` for `aws_appautoscaling_target`

Scalable targets created before 2023-03-20 may not have an assigned arn.
These resource cannot use tags or participate in default_tags.
To prevent terraform plan showing differences that can never be reconciled, use the lifecycle.ignore_changes meta-argument
Reference: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/appautoscaling_target
---
 main.tf      | 5 +++--
 variables.tf | 6 ++++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/main.tf b/main.tf
index 364e1dc..dcee575 100644
--- a/main.tf
+++ b/main.tf
@@ -290,9 +290,10 @@ resource "aws_appautoscaling_target" "this" {
   tags = var.tags
 
   lifecycle {
-    ignore_changes = [
+    ignore_changes = var.autoscaling_tags_ignore ? [
+      tags,
       tags_all,
-    ]
+    ] : []
   }
 }
 
diff --git a/variables.tf b/variables.tf
index 8b49969..b14c1d3 100644
--- a/variables.tf
+++ b/variables.tf
@@ -590,6 +590,12 @@ variable "autoscaling_target_connections" {
   default     = 700
 }
 
+variable "autoscaling_tags_ignore" {
+  description = "Scalable targets created before 2023-03-20 cannot use tags or default_tags. To prevent terraform plan showing differences that can never be reconciled, set this flag to true"
+  type        = bool
+  default     = false
+}
+
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