How to define execution order without trigger option in terraform

Question

Does it make sense to understand that it runs in the order defined in main.tf of terraform?

I understand that it is necessary to describe the trigger option in order to define the order on terraform.

but if it could not be used trigger option like this data "external" , How can I define the execution order?

For example, I would like to run in order as follows.

get_my_public_ip -> ec2 -> db -> test_http_status

main.tf is as follows

data "external" "get_my_public_ip" {
  program = ["sh", "scripts/get_my_public_ip.sh"]
}

module "ec2" {
  ...
}

module "db" {
  ...
}


data "external" "test_http_status" {
  program = ["sh", "scripts/test_http_status.sh"]
}

Solution

I can only provide feedback on the code you provided but one way to ensure the test_status command is run once the DB is ready is to use a depends_on within a null_resource

resource "null_resource" "test_status" {
  depends_on = ["module.db.id"] #or any output variable
  provisioner "local-exec" {
    command = "scripts/test_http_status.sh"
  }
}

But as @JimB already mentioned terraform isn't procedural so ensuring order isn't possible.

Comments

[JimB]

Terraform configuration is declarative, not procedural. The order the resources are declared has no bearing on the order that are executed. The only resource with a 'triggers" attribute is the null_resource, but an reference between resources created a dependency.

[Rıfat Erdem Sahin]

depends_on works with any resource ? or does it have to be a module ?

[Stephen]

it works with any resource - terraform.io/intro/getting-started/…