CODEWITHSUNDEEP
amazon-web-servicesterraform
Evan Gertis
Evan Gertis

Reputation: 2062

Error: Incorrect attribute value type module.network.private_subnets[0] is tuple with 3 elements

I am running into an issue while trying to upgrade from terraform 11 to terraform 12. I was previously using the following syntax to retrieve the 3rd element from a list of ids from a module. The module output is like so:

# Subnets
output "private_subnets" {
  description = "List of IDs of private subnets"
  value       = ["${aws_subnet.private.*.id}"]
}

Previously, this worked with terraform 11

subnet_id              = "${element(module.network.private_subnets,3)}"

I thought that I could use the index of 2 to get the same results, but I get the following error:

Error: Incorrect attribute value type

  on terraformfile.tf line 65, in resource "aws_instance" "myinstance":
  65:   subnet_id              = module.network.private_subnets[2]
    |----------------
    | module.network.private_subnets[2] is tuple with 3 elements

Any help with this would be greatly appreciated.

Upvotes: 3

Views: 7115

Answers (4)

Galina Kaz
Galina Kaz

Reputation: 11

I had same issue , flatten HELPED !! .

the configuration file looked like this :

resource "aws_db_subnet_group" "for-database" {
  name       = "for-database"
  description = "private subnets in different AZs"
  subnet_ids = module.vpc.private_subnets
}

got this error :

│ Error: Unsupported attribute │ │ 39: value = module.vpc.private_subnets.subnet_count │ ├──────────────── │ │ module.vpc.private_subnets is tuple with 2 elements │ │ This value does not have any attributes.

solution:

resource "aws_db_subnet_group" "for-database" {
  name       = "for-database"
  description = "private subnets in different AZs"
  subnet_ids = flatten([module.vpc.private_subnets])
}

Upvotes: 1

Mansur Ul Hasan
Mansur Ul Hasan

Reputation: 3606

it was quite difficult for me but i handled it via flatten function i took tuple and pass it to flatten function

/* Subnets group for DBs */
resource "aws_db_subnet_group" "default" {
  name       = "main"
  subnet_ids = flatten([aws_subnet.PrivateSubnets.*.id])

  tags = {
    Name = "Private Subnet group"
  }
}

Upvotes: -1

kiran01bm
kiran01bm

Reputation: 732

The answer from @Marcin holds good but I hit a very similar error in a slightly different situation and I took a different approach to resolve it.

Lets say you have a aws_security_group_rule rule and each of the data -sourced item in the list below i.e data.aws_subnet.app1_subnets.*.cidr_block and data.aws_subnet.app2_subnets.*.cidr_block are a tuple with lets say X elements - You might hit an error -

Error: Incorrect attribute value type

  on stack.tf line 44, in resource "aws_security_group_rule" "ds_security_group_ingress_rule":
  44:   cidr_blocks = [
  45:     data.aws_subnet.app1_subnets.*.cidr_block,
  46:     data.aws_subnet.app2_subnets.*.cidr_block
  47:   ]
    |----------------
    | data.aws_subnet.app1_subnets.*.cidr_block is tuple with 3 elements
    | data.aws_subnet.app2_subnets.*.cidr_block is tuple with 3 elements

Inappropriate value for attribute "cidr_blocks": element 0: string required.

I had to use the flatten function to resolve the issue which quite literally flattens the content..

Change the below:

cidr_blocks = [
data.aws_subnet.app1_subnets.*.cidr_block,
data.aws_subnet.app2_subnets.*.cidr_block
]

as

cidr_blocks = flatten([
data.aws_subnet.app1_subnets.*.cidr_block,
data.aws_subnet.app2_subnets.*.cidr_block
])

Upvotes: 3

Marcin
Marcin

Reputation: 238957

The currently used value:

 value       = ["${aws_subnet.private.*.id}"]

produces a list of lists. For example,

[
  [
    "subnet-0f5b759e80ffcf305",
    "subnet-0500c8c2a40e5b381",
  ],
]

If you want to keep using this in that form, later, when you use element you have to do following:

subnet_id  = element(module.network.private_subnets[0], 3)

Alternatively, redefine private_subnets to be:

 value       = aws_subnet.private.*.id

Upvotes: 2

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