How to use value from bash script when creating resource via terraform

Question

This is a generic workflow terraform question (I am a terraform beginner).

I need to create a new aws resource via terraform. The structure I have is

resource "some_aws_resource" "resource_name" {
   name = var.resource_name
   role_name = var.role_name

   another_key = another_value
}

The value another_value is derived from vars entered by the user through a bash script find_another_value.sh for example

resource "null_resource" "find_another_value" {
   provisioner "local-exec" {
      command     = "shell_scripts/find_another_value.sh"
    interpreter = ["/bin/bash"]
    working_dir = path.module

    environment = {
      DAR = var.aws_dar
      RAD = var.aws_rad
    }
   }

}

should return another_value

How do I pass the output another_value of the null_resource to the first resource and make sure that the non null resource waits until the null_resource returns the value?

The find_another_value.sh script will use the input variables to query aws via the aws cli to find the value it needs to return.

If there is a better/easier way that would also be good to know.

You can't do this. null_resource is not for returning anything to TF. I think you have to re-thing your design as Marko suggested. — Marcin
– Marcin, Commented Oct 2, 2022 at 10:46
@MarkoE I have to execute complicated logic in find_another_value.sh: retrieve some values using the aws cli. — user2175783
– user2175783, Commented Oct 2, 2022 at 22:30
@MarkoE In one use case it is the organizational unit where I want to place a new account — user2175783
– user2175783, Commented Oct 3, 2022 at 14:39

eliya · Accepted Answer · 2022-10-02 11:37:52Z

1

For waiting you will use depends_on = []

resource "some_aws_resource" "resource_name" {
   depends_on =[null_resource.find_another_value]
   name = var.resource_name
   role_name = var.role_name
   another_key = another_value.value
}

To extract value from a resource We will write a resource out We will add value Edit the resource then the name and then the line we want its value

output "another_value" {

  description = "another_value from null resource find_another_value ."

  value = null_resource.find_another_value.provisioner "local-exec"
}

edited Oct 2, 2022 at 11:37

answered Oct 2, 2022 at 9:23

eliya

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1 Comment

Alex Over a year ago

The syntax is not correct for this line: value = null_resource.find_another_value.provisioner "local-exec" "local-exec" is not expected there

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