xdr-terraform-modules/base/sensu/private_elb.tf

# lb ports
locals {
  alb_listener_ports = {
    ui    = "8000"
    api   = "8080"
    agent = "8081"
  }
}

#----------------------------------------------------------------------------
# INTERNAL LB
#----------------------------------------------------------------------------

resource "aws_alb" "sensu_internal" {
  name                       = "sensu-alb-internal-${var.environment}"
  security_groups            = [aws_security_group.sensu_alb_server_internal.id]
  internal                   = true
  subnets                    = var.private_subnets
  load_balancer_type         = "application"
  drop_invalid_header_fields = true

  access_logs {
    bucket  = "xdr-elb-${var.environment}"
    enabled = true
  }

  tags = merge(local.standard_tags, var.tags, { Name = "sensu-alb-internal-${var.environment}" })
}

resource "aws_alb_target_group" "sensu_internal" {
  for_each = local.alb_listener_ports
  name     = "sensu-alb-targets-${each.key}"
  port     = each.value
  protocol = "HTTPS"
  #deregistration_delay = "${local.lb_deregistration_delay}"
  vpc_id = var.vpc_id

  health_check {
    protocol = "HTTPS"
    port     = "8080"
    path     = "/health"
    matcher  = "200"
    timeout  = "4"
    interval = "5"
  }

  stickiness {
    type    = "lb_cookie"
    enabled = false
  }

  tags = merge(local.standard_tags, var.tags)
}

resource "aws_lb_target_group_attachment" "sensu_internal" {
  for_each         = local.alb_listener_ports
  target_group_arn = aws_alb_target_group.sensu_internal[each.key].arn
  target_id        = aws_instance.instance.id
  port             = each.value
}

# Create a new alb listener
resource "aws_alb_listener" "sensu_internal" {
  for_each          = local.alb_listener_ports
  load_balancer_arn = aws_alb.sensu_internal.arn
  port              = each.value
  protocol          = "HTTPS"
  ssl_policy        = "ELBSecurityPolicy-FS-1-2-Res-2020-10" # PFS, TLS1.2, and GCM; most "restrictive" policy
  certificate_arn   = aws_acm_certificate.cert.arn

  default_action {
    target_group_arn = aws_alb_target_group.sensu_internal[each.key].arn
    type             = "forward"
  }
}

#DNS Alias for the LB ( the CNAME was required. an Alias did NOT work due to aws/bug. )
resource "aws_route53_record" "sensu_internal" {
  zone_id  = var.dns_info["private"]["zone_id"]
  name     = var.instance_name
  type     = "CNAME"
  records  = [aws_alb.sensu_internal.dns_name]
  ttl      = "60"
  provider = aws.c2
}

#----------------------------------------------------------------------------
# ALB Security Group
#----------------------------------------------------------------------------

resource "aws_security_group" "sensu_alb_server_internal" {
  vpc_id      = var.vpc_id
  name        = "sensu-alb-sg-internal"
  description = "Sensu Internal LB SG"
  tags        = merge(local.standard_tags, var.tags)
}

#----------------------------------------------------------------------------
# INGRESS
#----------------------------------------------------------------------------


resource "aws_security_group_rule" "sensu_from_vpc" {
  for_each          = local.alb_listener_ports
  type              = "ingress"
  from_port         = each.value
  to_port           = each.value
  protocol          = "tcp"
  cidr_blocks       = ["10.0.0.0/8"]
  description       = "Sensu ${each.key}"
  security_group_id = aws_security_group.sensu_alb_server_internal.id
}

#----------------------------------------------------------------------------
# EGRESS
#----------------------------------------------------------------------------

resource "aws_security_group_rule" "sensu_from_alb" {
  for_each                 = local.alb_listener_ports
  type                     = "egress"
  from_port                = each.value
  to_port                  = each.value
  protocol                 = "tcp"
  source_security_group_id = aws_security_group.instance_security_group.id
  description              = "Sensu ${each.key}"
  security_group_id        = aws_security_group.sensu_alb_server_internal.id
}