so I am trying to do interpolation i-e with public scheme and terraform.workspace so subnets will dynamically get selected. For that tried merging terraform.workspace with elb_subnets but its throwing error that only supported key for 'terraform.X' interpolations is 'workspace'

variable "elb_scheme" {
  default = "public"

variable "prod_elb_subnets" {
  type = "map"

  default = {
    public  = "subnet-23ywe324, subnet-234hj34, subnet-cdh7868"
    private = "subnet-hj3h2323, subnet-jihi782, subnet-237dew"

variable "qa_elb_subnets" {
  type = "map"

  default = {
    public  = "subnet-234ee234, subnet-da238sdf, subnet-sd2233"
    private = "subnet-09jsdf23, subnet-hi232rf, subnet-89832w32"

  setting {
    namespace = "aws:ec2:vpc"
    name      = "ELBSubnets"

    value = "${var.(terraform.workspace_elb_subnets["${var.elb_scheme}"])}"


Error: module.ebs.aws_elastic_beanstalk_environment.beanstalk: 1 error(s) occurred:

* module.ebs.aws_elastic_beanstalk_environment.beanstalk: terraform.workspace_elb_subnets: only supported key for 'terraform.X' interpolations is 'workspace'

Terraform workspace

terraform workspace list
* qa

Can you tag your subnets? Its easier to use a datasource lookup based off environment then to hard code them in a variable.

Something like this if you just need the ids

data "aws_subnet_ids" "subnets" {

  tags {
    Env = "${terraform.workspace}"

If your subnets are tagged with the workspace then you can use them like

TO get a single subnet based on count

"${element(data.aws_subnet_ids.subnets.ids, count.index)}" 

To get them all in a list


See the following for more info


Datasources are very usefull and you should look into using them and not hard code anything.

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