CODEWITHSUNDEEP
amazon-web-servicesamazon-ec2syntaxterraformamazon-elb
Mahela Wickramasekara
Mahela Wickramasekara

Reputation: 733

Terraform syntax help to include instance ids from two instances to a single array

This is how my code looks,

module "alb_api" {
  source = "./modules/load-balancer"
  env = "${lower(var.env)}"
  project = "api"
  vpc_id = "${data.aws_vpc.main.id}"
  public_subnet1_id = "${var.public_subnet1_id}"
  public_subnet2_id = "${var.public_subnet2_id}"
  health_check_target_group_path = "/status"
  certificate_arn = "${var.certificate_arn}"
  alb_target_group_port = "1984"
  current_ec2_instance_ids = "${aws_instance.ec2[*].id}"
  next_ec2_instance_ids = "${aws_instance.next_ec2[*].id}"
}

I need to be able to combine instances Ids from two instances to a single array

Expectation

ec2_instance_ids = "${aws_instance.ec2[*].id},${aws_instance.next_ec2[*].id}"

This give me a syntax error, Is it possible to achieve this ? what would be the proper syntax is so ?

Inside the module I'm registering these instances to a load-balancer, code below

resource "aws_alb_target_group_attachment" "alb_target_group_attachment" {
  count = length("${var.current_ec2_instance_ids}")
  target_group_arn = "${aws_alb_target_group.alb_target_group.arn}"
  target_id = "${var.current_ec2_instance_ids[count.index]}"
  port = "${var.alb_target_group_port}"
}

resource "aws_alb_target_group_attachment" "next_alb_target_group_attachment" {
  count = length("${var.next_ec2_instance_ids}")
  target_group_arn = "${aws_alb_target_group.alb_target_group.arn}"
  target_id = "${var.next_ec2_instance_ids[count.index]}"
  port = "${var.alb_target_group_port}"
}

I need to combine these to a single as well

resource "aws_alb_target_group_attachment" "alb_target_group_attachment" {
  count = length("${var.ec2_instance_ids}")
  target_group_arn = "${aws_alb_target_group.alb_target_group.arn}"
  target_id = "${var.ec2_instance_ids[count.index]}"
  port = "${var.alb_target_group_port}"
}

Current version of code

module "alb_example-backend" {
  source = "./modules/load-balancer"
  env = "${lower(var.env)}"
  project = "example-backend"
  vpc_id = "${data.aws_vpc.main.id}"
  public_subnet1_id = "${var.public_subnet1_id}"
  public_subnet2_id = "${var.public_subnet2_id}"
  health_check_target_group_path ="/status"
  certificate_arn = "${var.certificate_arn}"
  alb_target_group_port = "2010"
  ec2_instance_ids = concat(aws_instance.ec2[*].id,aws_instance.next_ec2[*].id)
}

resource "aws_alb_target_group_attachment" "alb_target_group_attachment" {
  count = length("${var.ec2_instance_ids}")
  target_group_arn = "${aws_alb_target_group.alb_target_group.arn}"
  target_id = "${var.ec2_instance_ids[count.index]}"
  port = "${var.alb_target_group_port}"
}

Upvotes: 0

Views: 379

Answers (1)

Marcin
Marcin

Reputation: 238319

To join two lists, aws_instance.ec2[*].id and aws_instance.next_ec2[*].id you can use concat. Since your syntax is for 0.11, then it would be:

ec2_instance_ids = "${concat(aws_instance.ec2.*.id, aws_instance.next_ec2.*.id)}"

For TF 0.12+:

ec2_instance_ids = concat(aws_instance.ec2[*].id, aws_instance.next_ec2[*].id)

Upvotes: 1

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