main.tf

data "aws_vpc" "vpc" {
  id = var.vpc_id
}

resource "random_id" "salt" {
  byte_length = 8
}

resource "aws_elasticache_replication_group" "redis" {
  replication_group_id       = format("${var.format_length}", "${var.name}-${var.env}")
  description                = "Terraform-managed ElastiCache replication group for ${var.name}-${var.env}"
  num_cache_clusters         = var.redis_clusters
  node_type                  = var.redis_node_type
  automatic_failover_enabled = var.redis_failover
  engine_version             = var.redis_version
  port                       = var.redis_port
  parameter_group_name       = aws_elasticache_parameter_group.redis_parameter_group.id
  subnet_group_name          = aws_elasticache_subnet_group.redis_subnet_group.id
  security_group_ids         = compact([aws_security_group.redis_security_group.id, var.enable_vpn_sg ? var.vpn_sg_id : ""])
  apply_immediately          = var.apply_immediately
  maintenance_window         = var.redis_maintenance_window
  snapshot_window            = var.redis_snapshot_window
  snapshot_retention_limit   = var.redis_snapshot_retention_limit
  tags                       = merge({ "Name" = format("tf-elasticache-%s", var.name) }, var.tags)
  transit_encryption_enabled = var.transit_encryption_enabled
  at_rest_encryption_enabled = var.at_rest_encryption_enabled
  auth_token                 = var.transit_encryption_enabled ? var.auth_token : null
}

resource "aws_elasticache_parameter_group" "redis_parameter_group" {
  name = replace(format("%.255s", lower(replace("tf-redis-${var.name}-${var.env}-${random_id.salt.hex}", "_", "-"))), "/\\s/", "-")

  description = "Terraform-managed ElastiCache parameter group for ${var.name}-${var.env}"

  # Strip the patch version from redis_version var
  family = "redis${replace(var.redis_version, "/\\.[\\d]+$/", "")}"
  dynamic "parameter" {
    for_each = var.redis_parameters
    content {
      name  = parameter.value.name
      value = parameter.value.value
    }
  }

  lifecycle {
    create_before_destroy = true
  }
  tags = merge({ "Name" = format("tf-elasticache-%s", var.name) }, var.tags)
}

resource "aws_elasticache_subnet_group" "redis_subnet_group" {
  name       = replace(format("%.255s", lower(replace("tf-redis-${var.name}-${var.env}", "_", "-"))), "/\\s/", "-")
  subnet_ids = var.subnets
  tags       = merge({ "Name" = format("tf-elasticache-%s", var.name) }, var.tags)
}