How to extract particular indexes from within a list?

Terraform
1

I’m trying to extract only particular indexes from the list.

Module Block

module "app_sg" {
  source        = "../modules/sg/sg_rules"
  ingress_rules = var.app_ingress_rules
  egress_rules  = var.app_egress_rules
  ingress_sg    = var.app_ingress_sg
  egress_sg     = var.app_egress_sg
  src_sg_id     = ["module.app_sgs.sg_id[0]", "module.app_sgs.sg_id[2]"]
  sg_id         = module.app_sgs.sg_id[0]
  depends_on    = [module.app_sgs]
}

Resource Block

# Application security group rules creation
resource "aws_security_group_rule" "ingress_cidr" {
  for_each          = var.ingress_rules != "" ? var.ingress_rules : {}
  type              = "ingress"
  from_port         = each.key
  to_port           = each.key
  protocol          = "tcp"
  security_group_id = var.sg_id
  cidr_blocks       = each.value
}

resource "aws_security_group_rule" "egress_cidr" {
  for_each          = var.egress_rules != "" ? var.egress_rules : {}
  type              = "egress"
  from_port         = each.key
  to_port           = each.key
  protocol          = "tcp"
  security_group_id = var.sg_id
  cidr_blocks       = each.value
}

resource "aws_security_group_rule" "ingress_sg" {
  for_each                 = var.ingress_sg != "" ? var.ingress_sg : {}
  type                     = "ingress"
  from_port                = each.key
  to_port                  = each.key
  protocol                 = "tcp"
  security_group_id        = var.sg_id
  source_security_group_id = var.src_sg_id
}

resource "aws_security_group_rule" "egress_sg" {
  for_each                 = var.egress_sg != "" ? var.egress_sg : {}
  type                     = "egress"
  from_port                = each.key
  to_port                  = each.key
  protocol                 = "tcp"
  security_group_id        = var.sg_id
  source_security_group_id = var.src_sg_id
}

While running terraform apply it throws an error like below

Error: Incorrect attribute value type

  on ../modules/sg/sg_rules/main.tf line 29, in resource "aws_security_group_rule" "ingress_sg":
  29:   source_security_group_id = var.src_sg_id
    |----------------
    | var.src_sg_id is tuple with 2 elements

Inappropriate value for attribute "source_security_group_id": string required.

Could someone please provide me a solution for this scenario? Eventually I need to pass multiple source_security_group_id within the security group rule. I have tried slice function, but it can extract only the start and end indexes.