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

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

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

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

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

# Create a new target group
resource "aws_alb_target_group" "external" {
  # 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     = "/"
    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" "external" {
  target_group_arn = aws_alb_target_group.external.arn
  target_id        = aws_instance.instance.id
  port             = 3080
}

# Create a new alb listener
resource "aws_alb_listener" "https_external" {
  load_balancer_arn = aws_alb.external.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.arn

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

resource "aws_lb_listener" "http_external" {
  load_balancer_arn = aws_alb.external.arn
  port              = "80"
  protocol          = "HTTP"

  default_action {
    type             = "redirect"

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

# #########################
# # DNS Entry
module "public_dns_record_for_alb" {
  source = "../../submodules/dns/public_ALIAS_record"

  name = var.instance_name
  target_dns_name = aws_alb.external.dns_name
  target_zone_id  = aws_alb.external.zone_id
  dns_info = var.dns_info

  providers = {
    aws.mdr-common-services-commercial = aws.mdr-common-services-commercial
  }
}

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

resource "aws_security_group" "alb_server_external" {
  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-external"
  description = "Teleport LB SG"
  tags = merge(var.standard_tags, var.tags)
  lifecycle {
    create_before_destroy = true
  }
}

#----------------------------------------------------------------------------
# INGRESS
#----------------------------------------------------------------------------
resource "aws_security_group_rule" "alb-http-in" {
  description = "HTTPS In"
  type = "ingress"
  from_port = "80"
  to_port = "80"
  protocol = "tcp"
  cidr_blocks = [ "0.0.0.0/0" ]
  security_group_id = aws_security_group.alb_server_external.id
}

resource "aws_security_group_rule" "alb-https-in" {
  description = "HTTPS In"
  type = "ingress"
  from_port = "443"
  to_port = "443"
  protocol = "tcp"
  cidr_blocks = [ "0.0.0.0/0" ]
  security_group_id = aws_security_group.alb_server_external.id
}

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

resource "aws_security_group_rule" "alb_to_server" {
  type              = "egress"
  from_port         = 443
  to_port           = 443
  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_external.id
}