main.tf

locals {
  port                 = var.port == "" ? var.engine == "aurora-postgresql" ? "5432" : "3306" : var.port
  master_password      = var.password == "" ? random_password.master_password.result : var.password
  name = "aurora-${var.name}"
}


# Random string to use as master password unless one is specified
resource "random_password" "master_password" {
  length  = 10
  special = false
}

resource "aws_db_subnet_group" "this" {

  name        = var.name
  description = "For Aurora cluster ${var.name}"
  subnet_ids  = var.subnets

  tags = merge(var.tags, {
    Name = local.name
  })
  
}

resource "aws_rds_cluster" "this" {
  global_cluster_identifier           = var.global_cluster_identifier
  cluster_identifier                  = var.name
  replication_source_identifier       = var.replication_source_identifier
  source_region                       = var.source_region
  engine                              = var.engine
  engine_mode                         = var.engine_mode
  engine_version                      = var.engine_version
  enable_http_endpoint                = var.enable_http_endpoint
  kms_key_id                          = var.kms_key_id
  database_name                       = var.database_name
  master_username                     = var.username
  master_password                     = local.master_password
  final_snapshot_identifier           = "${var.final_snapshot_identifier_prefix}-${var.name}-${random_id.snapshot_identifier.hex}"
  skip_final_snapshot                 = var.skip_final_snapshot
  deletion_protection                 = var.deletion_protection
  backup_retention_period             = var.backup_retention_period
  preferred_backup_window             = var.preferred_backup_window
  preferred_maintenance_window        = var.preferred_maintenance_window
  port                                = local.port
  db_subnet_group_name                = aws_db_subnet_group.this.name
  vpc_security_group_ids              = var.vpc_security_groups
  snapshot_identifier                 = var.snapshot_identifier
  storage_encrypted                   = var.storage_encrypted
  apply_immediately                   = var.apply_immediately
  db_cluster_parameter_group_name     = var.db_cluster_parameter_group_name
  iam_database_authentication_enabled = var.iam_database_authentication_enabled
  copy_tags_to_snapshot               = var.copy_tags_to_snapshot
  iam_roles                           = var.iam_roles

  enabled_cloudwatch_logs_exports = var.enabled_cloudwatch_logs_exports

  timeouts {
    create = var.timeouts
    update = var.timeouts
    delete = var.timeouts
  }

  dynamic "scaling_configuration" {
    for_each = length(keys(var.scaling_configuration)) == 0 ? [] : [
    var.scaling_configuration]

    content {
      auto_pause               = lookup(scaling_configuration.value, "auto_pause", null)
      max_capacity             = lookup(scaling_configuration.value, "max_capacity", null)
      min_capacity             = lookup(scaling_configuration.value, "min_capacity", null)
      seconds_until_auto_pause = lookup(scaling_configuration.value, "seconds_until_auto_pause", null)
      timeout_action           = lookup(scaling_configuration.value, "timeout_action", null)
    }
  }

  tags = var.tags
}

resource "aws_rds_cluster_instance" "this" {
  count = var.replica_scale_enabled ? var.replica_scale_min : var.replica_count

  identifier                      = "${var.name}-${count.index + 1}"
  cluster_identifier              = aws_rds_cluster.this.id
  engine                          = var.engine
  engine_version                  = var.engine_version
  instance_class                  = var.instance_type
  publicly_accessible             = var.publicly_accessible
  db_subnet_group_name            = aws_db_subnet_group.this.name
  db_parameter_group_name         = var.db_parameter_group_name
  preferred_maintenance_window    = var.preferred_maintenance_window
  apply_immediately               = var.apply_immediately
  monitoring_role_arn             = var.iam_role_enhanced_monitoring_arn
  monitoring_interval             = var.monitoring_interval
  auto_minor_version_upgrade      = var.auto_minor_version_upgrade
  promotion_tier                  = count.index + 1
  performance_insights_enabled    = var.performance_insights_enabled
  performance_insights_kms_key_id = var.performance_insights_kms_key_id
  ca_cert_identifier              = var.ca_cert_identifier
  
  timeouts {
    create = var.timeouts
    update = var.timeouts
    delete = var.timeouts
  }


  tags = var.tags
}

resource "random_id" "snapshot_identifier" {
  keepers = {
    id = var.name
  }

  byte_length = 4
}

resource "aws_appautoscaling_target" "read_replica_count" {
  count = var.replica_scale_enabled ? 1 : 0

  max_capacity       = var.replica_scale_max
  min_capacity       = var.replica_scale_min
  resource_id        = "cluster:${aws_rds_cluster.this.cluster_identifier}"
  scalable_dimension = "rds:cluster:ReadReplicaCount"
  service_namespace  = "rds"
}

resource "aws_appautoscaling_policy" "autoscaling_read_replica_count" {
  count = var.replica_scale_enabled ? 1 : 0

  name               = "target-metric"
  policy_type        = "TargetTrackingScaling"
  resource_id        = "cluster:${aws_rds_cluster.this.cluster_identifier}"
  scalable_dimension = "rds:cluster:ReadReplicaCount"
  service_namespace  = "rds"

  target_tracking_scaling_policy_configuration {
    predefined_metric_specification {
      predefined_metric_type = var.predefined_metric_type
    }

    scale_in_cooldown  = var.replica_scale_in_cooldown
    scale_out_cooldown = var.replica_scale_out_cooldown
    target_value       = var.predefined_metric_type == "RDSReaderAverageCPUUtilization" ? var.replica_scale_cpu : var.replica_scale_connections
  }

  depends_on = [aws_appautoscaling_target.read_replica_count]
}