Variable reference to "self" or "this"?

[Cameron Stokes]

I'm looking at using Terraform to manage Route53 records and am having to duplicate name values over and over. Is it possible to not do this? Perhaps with a ${this.name} macro or something?

In the example below, I'd like to avoid duplicating the corresponding www value for each and every record.

resource "aws_route53_zone" "example" {

   name = "example.com"

}

resource "aws_route53_record" "www" {

   zone_id = "${aws_route53_zone.example.zone_id}"

   name = "www.${aws_route53_zone.example.name}"

   type = "A"

   ttl = "60"

   records = ["127.0.0.1"]

}

Is something like below possible?

resource "aws_route53_zone" "example" {

   name = "example.com"

}

resource "aws_route53_record" "www" {

   zone_id = "${aws_route53_zone.example.zone_id}"

   name = "${this.name}.${aws_route53_zone.example.name}"

   type = "A"

   ttl = "60"

   records = ["127.0.0.1"]

}

[Armon Dadgar]

Hey Cameron,

I think this is interesting but I think there is a balance of syntactic sugar vs language complexity.

Curious to hear others chime in.

Best Regards,

Armon Dadgar

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[Dave Dash]

I’m not sure if *that* is what I want, but I do know that I want something that lets me in a single definition create a route53 record for *all* the instances I’ve created in terraform following a specific pattern.

e.g.

${aws_instance.*.tag.Name}.mysite.net

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[Cameron Stokes]

I've not yet started managing instances with Terraform, but I could see this being valuable with instances as well.

Using the example from the docs:

resource "aws_instance" "HelloWorld" {

    ami = "ami-1234"

    instance_type = "m1.small"

    tags {

        Name = "${this.name}"

    }

}

[William Valadez]

This would be extremely useful. We set the name tag for AWS instances, and use the name as part of our provisioning script as well. Currently we write out the resource name at least 3 times for every new AWS resource created. It would be much easier to self reference the name with a variable.

[David Cunningham]

It would be useful to get the Terraform name of a resource from inside that resource.  With GCP you end up duplicating the name of instances, as there is a GCP name and a Terraform name, and at least in my scripts they are always the same.  I could avoid that with something as simple as ${resource_name}.  Trivial example:

resource "google_compute_address" "test" {

    name = "test"

}

becomes 

resource "google_compute_address" "test" {

    name = "${resource_name}"

}

It would actually be enough for this case if the name attribute could default to the resource name.  However I'm not sure if that's possible within the existing provider model, and it also doesn't allow interpolation, so doesn't cover these AWS cases where you want to build a string out of the name.

I don't understand why you'd want to call it ${this.name} though.  I'd expect ${this.name} to return the name attribute of this, so the original example would be a self-referential infinite loop.  Is it suggested that all attributes be visible from this?  E.g. ${this.instance_type} ?

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