xdr-terraform-modules/base/teleport-single-instance/alb-internal.tf

#----------------------------------------------------------------------------
# EXTERNAL APPLICATION LB
#----------------------------------------------------------------------------

resource "aws_alb" "internal" {
  name               = "${var.instance_name}-alb-internal-${var.environment}"
  security_groups    = [ aws_security_group.alb_server_internal.id ]
  internal           = true 
  subnets            = var.subnets
  load_balancer_type = "application"

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

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

# Create a new target group
resource "aws_alb_target_group" "internal" {
  # use name_prefix instead of name and create-before-destroy on security groups and alb target groups to make future changes easier,
  # otherwise, you get stuck in `destroying` during routine changes.
  name_prefix          = substr(var.instance_name, 0, 6)
  port                 = 3080
  protocol             = "HTTPS"
  #deregistration_delay = "${local.lb_deregistration_delay}"
  vpc_id               = var.vpc_id

  health_check {
    protocol = "HTTPS"
    port     = "3080"
    path     = "/web/login"
    matcher  = "200-400"
    timeout  = "4"
    interval = "5"
  }

  stickiness {
    type    = "lb_cookie"
    enabled = true 
  }

  tags = merge(var.standard_tags, var.tags)
  lifecycle {
    create_before_destroy = true
  }
}

resource "aws_lb_target_group_attachment" "internal" {
  target_group_arn = aws_alb_target_group.internal.arn
  target_id        = aws_instance.instance.id
  port             = 3080
}

# Create a new alb listener
resource "aws_alb_listener" "https_internal" {
  load_balancer_arn = aws_alb.internal.arn
  port              = "443"
  protocol          = "HTTPS"
  ssl_policy        = "ELBSecurityPolicy-FS-1-2-Res-2019-08" # PFS, TLS1.2, most "restrictive" policy (took awhile to find that)
  certificate_arn   = aws_acm_certificate.cert_internal.arn

  default_action {
    target_group_arn = aws_alb_target_group.internal.arn
    type             = "forward"
  }
}

resource "aws_alb_listener" "alb_3080_internal" {
  load_balancer_arn = aws_alb.internal.arn
  port              = "3080"
  protocol          = "HTTPS"
  ssl_policy        = "ELBSecurityPolicy-FS-1-2-Res-2019-08" # PFS, TLS1.2, most "restrictive" policy (took awhile to find that)
  certificate_arn   = aws_acm_certificate.cert_internal.arn

  default_action {
    target_group_arn = aws_alb_target_group.internal.arn
    type             = "forward"
  }
}

resource "aws_lb_listener" "http_internal" {
  load_balancer_arn = aws_alb.internal.arn
  port              = "80"
  protocol          = "HTTP"

  default_action {
    type             = "redirect"

    redirect {
      port        = "443"
      protocol    = "HTTPS"
      status_code = "HTTP_301"
    }
  }
}

# #########################
# # DNS Entry
module "private_alb_dns_record" {
  source = "../../submodules/dns/private_CNAME_record"

  name = "${var.instance_name}-alb.${var.dns_info["private"]["zone"]}"
  target_dns_names = [ aws_alb.internal.dns_name ]
  dns_info = var.dns_info

  providers = {
    aws.c2 = aws.c2
  }
}

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

resource "aws_security_group" "alb_server_internal" {
  vpc_id      = var.vpc_id
  # use name_prefix instead of name and create-before-destroy on security groups and alb target groups to make future changes easier,
  # otherwise, you get stuck in `destroying` during routine changes.
  name_prefix = "${var.instance_name}-alb-sg-internal"
  description = "Teleport LB SG"
  tags = merge(var.standard_tags, var.tags)
  lifecycle {
    create_before_destroy = true
  }
}

#----------------------------------------------------------------------------
# INGRESS
#----------------------------------------------------------------------------
resource "aws_security_group_rule" "alb-internal-http-in" {
  description = "HTTPS In"
  type = "ingress"
  from_port = "80"
  to_port = "80"
  protocol = "tcp"
  cidr_blocks = [ "10.0.0.0/8" ]
  security_group_id = aws_security_group.alb_server_internal.id
}

resource "aws_security_group_rule" "alb-internal-https-in" {
  description = "HTTPS In"
  type = "ingress"
  from_port = "443"
  to_port = "443"
  protocol = "tcp"
  cidr_blocks = [ "10.0.0.0/8" ]
  security_group_id = aws_security_group.alb_server_internal.id
}

resource "aws_security_group_rule" "alb-internal-3080-in" {
  description = "3080 In"
  type = "ingress"
  from_port = "3080"
  to_port = "3080"
  protocol = "tcp"
  cidr_blocks = [ "10.0.0.0/8" ]
  security_group_id = aws_security_group.alb_server_internal.id
}

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

resource "aws_security_group_rule" "alb_internal-to_server" {
  type              = "egress"
  from_port         = 3080
  to_port           = 3080
  protocol          = "tcp"
  source_security_group_id = aws_security_group.instance.id
  description       = "Allows the ALB to talk to the Sensu servers"
  security_group_id = aws_security_group.alb_server_internal.id
}