Modules and Remote State (Terraform v0.12.10)

Terraform
1

Hi, I want to build a basic stack on AWS using terraform-aws-modules, I write an network/main.tf to start a network stack, this is my tf file:

Hi, I want to build a basic stack on AWS using terraform-aws-modules, I write an network/main.tf to start a network stack, this is my tf file:

provider "aws" {
  region = "us-west-1"
  profile = "dev"
}

terraform {
  backend "s3" {
    bucket = "my-state-bucket"
    key = "DR/network/terraform.tfstate"
    encrypt = true
    region = "us-east-1"
    }
}
module "vpc" {
  source = "terraform-aws-modules/vpc/aws"

  name = "my-vpc"
  cidr = "10.1.0.0/16"

  azs             = ["us-west-1a", "us-west-1b"]
  private_subnets = ["10.1.1.0/19", "10.1.32.0/19"]
  public_subnets  = ["10.1.96.0/19", "10.1.128.0/19"]

  enable_nat_gateway = true
  enable_vpn_gateway = true

  tags = {
    Terraform = "true"
    Environment = "DR"
  }
}

output "vpc_id" {
  description = "The ID of the VPC"
  value      = "${module.vpc.vpc_id}"
}

output "private_subnets" {
  description = "List of IDs of private subnets"
  value       = "${module.vpc.*.private_subnets}"
}
output "public_subnets" {
  description = "List of IDs of public subnets"
  value       = "${module.vpc.*.public_subnets}"
}

and here my ec2 instance tf file

provider "aws" {
  region = "us-west-1"
  profile = "dev"
}

terraform {
  backend "s3" {
    bucket = "
    key = "DR/instances/terraform.tfstate"
    encrypt = true
    region = "us-east-1"
    }
}

data "terraform_remote_state" "network" {
	backend = "s3"
	config = {
		bucket = "my-state-bucket"
		key = "DR/network/terraform.tfstate"
		region = "us-east-1"
	}
}

data "terraform_remote_state" "misc" {
	backend = "s3"
	config = {
		bucket = "my-state-bucket"
		key = "DR/misc/terraform.tfstate"
		region = "us-east-1"
	}
}

variable "ami_base" {
    default = "ami-0245d318c6788de52"
}

variable "instance_type" {
    default = "t2.micro"
}

module "ec2_cluster" {
  source                 = "terraform-aws-modules/ec2-instance/aws"
  version                = "~> 2.0"

  name                   = "My EC2"
  instance_count         = 1

  ami                    = var.ami_base
  instance_type          = var.instance_type
  key_name               = data.terraform_remote_state.misc.outputs.keypair
  monitoring             = true
  vpc_security_group_ids = ["sg-12345678"]
  subnet_id              = element(data.terraform_remote_state.network.outputs.private_subnets, 0)
  tags = {
    Terraform   = "true"
    Environment = "DR"
  }
}

but when I run terraform plan I got this error:

Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.

data.terraform_remote_state.misc: Refreshing state...
data.terraform_remote_state.network: Refreshing state...

Error: Invalid value for module argument

  on ec2.tf line 53, in module "ec2_cluster":
  53:   subnet_id              = element(data.terraform_remote_state.network.outputs.private_subnets, 0)

The given value is not suitable for child module variable "subnet_id" defined
at
.terraform/modules/ec2_cluster/terraform-aws-modules-terraform-aws-ec2-instance-9fe491f/variables.tf:75,1-21:
string required.

how can I select one of this two private subnets to my instance in Terraform 0.12.10? I’d like to use this with remote state.

Thanks

2

@ [orelhinhas] Have you found a solution? I’m running into exactly same problem.