Finalize valkey config

- Optimal node size for cpu utilization
- Configurable replica count
- Include engine logs for deeper insight

Author: TheOneFromNorway

terraform/app/env/preview.tfvars

@@ -23,4 +23,6 @@ appspec_bucket       = "nhse-mavis-appspec-bucket-preview"
 minimum_web_replicas = 2
 maximum_web_replicas = 4
 
-valkey_node_type = "cache.t4g.micro"
+valkey_node_type          = "cache.t4g.micro"
+valkey_log_retention_days = 3
+valkey_failover_enabled   = false

terraform/app/env/sandbox-alpha.tfvars

@@ -23,4 +23,5 @@ good_job_replicas    = 1
 
 valkey_node_type          = "cache.t4g.micro"
 valkey_log_retention_days = 3
+valkey_failover_enabled   = false
 sidekiq_replicas          = 1

terraform/app/env/sandbox-beta.tfvars

@@ -24,4 +24,5 @@ good_job_replicas    = 1
 # Valkey serverless configuration - minimal settings for sandbox
 valkey_node_type          = "cache.t4g.micro"
 valkey_log_retention_days = 3
+valkey_failover_enabled   = false
 sidekiq_replicas          = 1

terraform/app/env/test.tfvars

@@ -21,4 +21,6 @@ appspec_bucket       = "nhse-mavis-appspec-bucket-test"
 minimum_web_replicas = 2
 maximum_web_replicas = 4
 
-valkey_node_type = "cache.t4g.micro"
+valkey_node_type          = "cache.t4g.micro"
+valkey_log_retention_days = 3
+valkey_failover_enabled   = false

terraform/app/env/training.tfvars

@@ -25,4 +25,6 @@ appspec_bucket       = "nhse-mavis-appspec-bucket-training"
 minimum_web_replicas = 2
 maximum_web_replicas = 4
 
-valkey_node_type = "cache.t4g.micro"
+valkey_node_type          = "cache.t4g.micro"
+valkey_log_retention_days = 3
+valkey_failover_enabled   = false

terraform/app/valkey.tf

@@ -35,38 +35,42 @@ resource "aws_elasticache_subnet_group" "valkey" {
   }
 }
 
-# ElastiCache Replication Group (cluster mode disabled for Sidekiq compatibility)
 resource "aws_elasticache_replication_group" "valkey" {
   replication_group_id = "mavis-cache-${var.environment}"
-  description          = "Valkey cluster for Sidekiq (cluster mode disabled)"
+  description          = "Valkey cluster for Sidekiq"
 
   engine               = "valkey"
   engine_version       = var.valkey_engine_version
   node_type            = var.valkey_node_type
   port                 = var.valkey_port
   parameter_group_name = aws_elasticache_parameter_group.valkey.name
 
-  # Cluster configuration (disabled for Sidekiq compatibility)
-  automatic_failover_enabled  = true
-  num_cache_clusters          = 2
+  automatic_failover_enabled  = var.valkey_failover_enabled
+  num_cache_clusters          = length(local.valkey_cache_availability_zones)
   subnet_group_name           = aws_elasticache_subnet_group.valkey.name
   security_group_ids          = [aws_security_group.valkey.id]
-  preferred_cache_cluster_azs = [aws_subnet.private_subnet_a.availability_zone, aws_subnet.private_subnet_b.availability_zone]
+  preferred_cache_cluster_azs = local.valkey_cache_availability_zones
   snapshot_retention_limit    = var.valkey_snapshot_retention_limit
   snapshot_window             = var.valkey_snapshot_window
   maintenance_window          = var.valkey_maintenance_window
 
   at_rest_encryption_enabled = true
   transit_encryption_enabled = true
 
-  # Logging
   log_delivery_configuration {
     destination      = aws_cloudwatch_log_group.valkey_slow_log.name
     destination_type = "cloudwatch-logs"
     log_format       = "text"
     log_type         = "slow-log"
   }
 
+  log_delivery_configuration {
+    destination      = aws_cloudwatch_log_group.valkey_engine_log.name
+    destination_type = "cloudwatch-logs"
+    log_format       = "json"
+    log_type         = "engine-log"
+  }
+
   tags = {
     Name    = "mavis-cache-${var.environment}"
     Purpose = "sidekiq-job-processing"
@@ -80,7 +84,7 @@ resource "aws_elasticache_parameter_group" "valkey" {
   # Optimize for Sidekiq workload
   parameter {
     name  = "maxmemory-policy"
-    value = "noeviction" #TODO: Optimize for sidekiq
+    value = "noeviction"
   }
 
   tags = {
@@ -96,3 +100,12 @@ resource "aws_cloudwatch_log_group" "valkey_slow_log" {
     Name = "mavis-cache-slow-log-${var.environment}"
   }
 }
+
+resource "aws_cloudwatch_log_group" "valkey_engine_log" {
+  name              = "/aws/elasticache/valkey/${var.environment}/engine-log"
+  retention_in_days = var.valkey_log_retention_days
+
+  tags = {
+    Name = "mavis-cache-engine-log-${var.environment}"
+  }
+}

terraform/app/variables.tf

@@ -354,8 +354,15 @@ variable "valkey_engine_version" {
 
 variable "valkey_node_type" {
   type        = string
-  default     = "cache.t2.medium"
-  description = "ElastiCache node type for Valkey (use cache.t3.micro for sandbox, cache.r6g.large+ for production)"
+  default     = "cache.m7g.large"
+  description = "ElastiCache node type for Valkey (use cache.t3.micro for sandbox, cache.m7g.large+ for production)"
+  nullable    = false
+}
+
+variable "valkey_failover_enabled" {
+  type        = bool
+  default     = true
+  description = "Enable automatic failover for Valkey cluster"
   nullable    = false
 }
 
@@ -372,14 +379,14 @@ variable "valkey_snapshot_retention_limit" {
 
 variable "valkey_snapshot_window" {
   type        = string
-  default     = "03:00-05:00"
+  default     = "00:00-02:00"
   description = "Daily snapshot window for Valkey (HH:MM-HH:MM format, UTC)"
   nullable    = false
 }
 
 variable "valkey_maintenance_window" {
   type        = string
-  default     = "sun:05:00-sun:06:00"
+  default     = "sun:02:00-sun:04:00"
   description = "Weekly maintenance window for Valkey (ddd:HH:MM-ddd:HH:MM format, UTC)"
   nullable    = false
 }
@@ -396,6 +403,7 @@ variable "valkey_log_retention_days" {
 }
 
 locals {
-  ecs_initial_lb_target_group = var.active_lb_target_group == "green" ? aws_lb_target_group.green.arn : aws_lb_target_group.blue.arn
-  ecs_sg_ids                  = [module.web_service.security_group_id, module.good_job_service.security_group_id, module.sidekiq_service.security_group_id]
+  ecs_initial_lb_target_group     = var.active_lb_target_group == "green" ? aws_lb_target_group.green.arn : aws_lb_target_group.blue.arn
+  ecs_sg_ids                      = [module.web_service.security_group_id, module.good_job_service.security_group_id, module.sidekiq_service.security_group_id]
+  valkey_cache_availability_zones = var.valkey_failover_enabled ? [aws_subnet.private_subnet_a.availability_zone, aws_subnet.private_subnet_b.availability_zone] : [aws_subnet.private_subnet_a.availability_zone]
 }