Fix cluster mode elasticache ignore values (#378)

Author: morozRed

aws/elasticache/README.md

@@ -43,6 +43,13 @@ module "elasticache" {
   # Compulsory for Cluster Mode
   shard_count = 2
   replicas_per_node_group = 1 # if set to 0, must disable multi-AZ
+
+  # Ignore engine version changes since AWS will auto-update minor version changes
+  lifecycle {
+    ignore_changes = [
+      engine_version,
+    ]
+  }
 }
 ```
 
@@ -62,7 +69,30 @@ Sidekiq does not work with cluster mode. The recommended setup is to have:
 * ca-central-1
 * sa-east-1
 
-As of July 2022. Also, you **must** use Reds `6.2` or later.
+As of July 2025. Also, you **must** use following versions of elasticache:
+
+- Redis `7.1` or later
+- Valkey `8.0` or later
+
+
+## Migration from Redis 6.2.6
+
+> 💡 We highly recommned migrating to a desired  engine and version right away to save time.
+
+If you're trying to migrate from <7 Redis version to any new version, you'll likely get an error like this:
+
+```
+Transit encryption mode is not supported for engine version 6.2.6. Please use engine version 7.0.5 or higher.
+```
+
+In order to successfully migrate you'll have to explicitly set this param to `null`:
+
+```
+# this will ensure that you'll update engine version successfully
+transit_encryption_mode = null
+```
+
+Once migrated you can enable `transit_encryption_mode` without replacing resource
 
 ## Outputs
 

aws/elasticache/elasticache.tf

@@ -75,13 +75,6 @@ resource "aws_elasticache_replication_group" "cluster_mode" {
     Project     = var.project
     Environment = var.environment
   }
-
-  # Ignore engine version changes since AWS will auto-update minor version changes
-  lifecycle {
-    ignore_changes = [
-      engine_version,
-    ]
-  }
 }
 
 locals {

aws/stack/app/elasticache.tf

@@ -14,6 +14,7 @@ module "elasticache" {
   ])))
 
   # optional
+  engine                     = var.elasticache_engine
   name                       = var.elasticache_name
   major_version              = var.elasticache_major_version
   node_type                  = var.elasticache_node_type

aws/stack/app/variables.tf

@@ -185,12 +185,24 @@ variable "elasticache_node_type" {
   default = "cache.t3.micro"
 }
 
+variable "elasticache_engine" {
+  type    = string
+  default = "redis"
+  validation {
+    condition     = contains(["redis", "valkey"], var.elasticache_engine)
+    error_message = "elasticache engine must be either 'redis' or 'valkey'"
+  }
+}
+
+locals {
+  major_version_bounds = var.elasticache_engine == "valkey" ? [7, 8] : [6, 7]
+}
 variable "elasticache_major_version" {
   type    = number
   default = 7
   validation {
-    condition     = var.elasticache_major_version >= 6 && var.elasticache_major_version <= 7
-    error_message = "elasticache major_version must be 6 or 7"
+    condition     = var.elasticache_major_version >= local.major_version_bounds[0] && var.elasticache_major_version <= local.major_version_bounds[1]
+    error_message = "elasticache_major_version must be ${local.major_version_bounds[0]} or ${local.major_version_bounds[1]}"
   }
 }