Terraform 0.12 + vpc module v2.2 (Inappropriate value for attribute "subnet_ids": element 0: string required.)

[marcincuber]

I am trying to upgrade my terraform but I am stuck at the following;

resource "aws_eks_cluster" "cluster" {
  enabled_cluster_log_types = ["api", "audit", "authenticator", "controllerManager", "scheduler"]
  name                      = "${var.cluster_name}-${var.environment}"
  role_arn                  = aws_iam_role.cluster.arn
  version                   = var.eks_version

  vpc_config {
    subnet_ids              = [module.vpc.public_subnets, module.vpc.private_subnets]
    security_group_ids      = [aws_security_group.cluster.id]
    endpoint_private_access = "true"
    endpoint_public_access  = "true"
  }
}

I am getting the error Inappropriate value for attribute "subnet_ids": element 0: string required.

Could someone advise what is the current way of referencing all subnets and passing them into subnet_ids variable?

Thanks

[marcincuber]

Found the solution to be subnet_ids = flatten([module.vpc.public_subnets, module.vpc.private_subnets]).

[saravana-code]

We are facing the same issue, is it related to any particular terraform version or the OS of the system where we run the "terraform plan/apply"?

[antonbabenko]

It can be also like this - subnet_ids = concat(module.vpc.public_subnets, module.vpc.private_subnets)

[sonianara]

I'm getting the same error doing something like this:

subnet_ids = ["${aws_subnet.priv_subnet.*.id}"]

Anyone have any idea how to resolve this?

[antonbabenko]

@sonianara You can always unwrap value between [ and ] to make it like this:

subnet_ids = "${aws_subnet.priv_subnet.*.id}"

[ammartaj53]

@antonbabenko it worked like a charm

[ozgiat]

@antonbabenko You saved me hours...
Can you explain whats the difference with [] and without ?

[antonbabenko]

[] - this adds a wrapping type list, so the type of the produced variable becomes list of lists.

[JPalmerGithub]

--- antonbabenko commented Nov 8, 2019
--- [] - this adds a wrapping type list, so the type of the produced variable becomes list of lists.
One big Thank You from here too, Sir

[AdeOpe]

OMG! i cannot say thank you enough for this page!

[demisx]

Should the docs be updated? I was running into the same error trying to create a NLB: https://www.terraform.io/docs/providers/aws/r/lb.html

This worked:

resource "aws_lb" "node_port" {
  ...
  subnets = data.aws_subnet_ids.private.ids
  ...

[sikemullivan]

I needed a combination of the answers above.

subnet_ids = concat("${aws_subnet.private.*.id}", "${aws_subnet.public.*.id}")

[vaibhavjpr]

I'm getting the same error doing something like this:

subnet_ids = ["${aws_subnet.priv_subnet.*.id}"]

Anyone have any idea how to resolve this?

I tried like this.

resource "aws_db_subnet_group" "dbsubnet" {
name = "testcluster"
subnet_ids = flatten(["${aws_subnet.private.*.id}"]) -- this one
tags = {
Name = "My DB subnet group"
}
}

[antonbabenko]

Try this syntax: subnet_ids = aws_subnet.priv_subnet.*.id

[alxsbn]

Error still prevalent in v0.14.5 with aws_vpc_endpoint

[andrewrotherham]

Removing the brackets has done the trick, but I'm still wondering why one is a list here but the other is a string. Shouldn't they both be stings? This code does work...but why does security_group_ids need the square brackets but subnet_ids doesn't?
vpc_config {
security_group_ids = ["${aws_security_group.demo-cluster.id}"]
subnet_ids = "${aws_subnet.demo.*.id}"

[Jonas-Noh]

i really want to found this problem, thank a lot.

[pete198016]

Hello,

#terraform provider 3.55.0

resource "aws_vpc_endpoint" "example" {
service_name = aws_vpc_endpoint_service.example.service_name
#subnet_ids = [module.vpc.natgwsub_subnets.*.id]
subnet_ids = module.vpc.natgwsub_subnets
vpc_endpoint_type = aws_vpc_endpoint_service.example.service_type
vpc_id = module.vpc.vpc_id
}

With subnet_ids i need to choose one subnet only - gateway load balancer requirement.
Tried many ways and i can't choose just one.

Example error:

Error: Incorrect attribute value type
on hub-eu/asg.hub-eu.tf line 117, in resource "aws_vpc_endpoint" "example":
subnet_ids = module.vpc.natgwsub_subnets[0]
Inappropriate value for attribute "subnet_ids": set of string required.

Anyone can help ?

[mkatajah]

Hello,

#terraform provider 3.55.0

resource "aws_vpc_endpoint" "example" {
service_name = aws_vpc_endpoint_service.example.service_name
#subnet_ids = [module.vpc.natgwsub_subnets.*.id]
subnet_ids = module.vpc.natgwsub_subnets
vpc_endpoint_type = aws_vpc_endpoint_service.example.service_type
vpc_id = module.vpc.vpc_id
}

With subnet_ids i need to choose one subnet only - gateway load balancer requirement.
Tried many ways and i can't choose just one.

Example error:

Error: Incorrect attribute value type
on hub-eu/asg.hub-eu.tf line 117, in resource "aws_vpc_endpoint" "example":
subnet_ids = module.vpc.natgwsub_subnets[0]
Inappropriate value for attribute "subnet_ids": set of string required.

Anyone can help ?

I encountered similar issue. You can try this: subnet_ids = toset([element(module.vpc.natgwsub_subnets.*.id,0)])

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