Import resources from module into state file

[ldelossa01]

Unless I'm missing something it seems that when creating a 'module' you must use output variables to export information from the module into the state using the module. This becomes cumbersome when you're not exactly sure which attributes you may need in the state you are writing.

Is it possible to export the entire resource to using state? For example:

I create a module called sandbox. The main.tf looks like this:

resource "aws_vpc" "sandbox-vpc" {
    ...
}

In my tf state file I could do the following:

module "sandbox" {
    source = "./sandbox"
}

resource "aws_internet_gateway" "ig01" {
    vpc_id = "${module.sandbox.aws_vpc.sandbox-vpc.id}"
}

Now I understand that I could make a output variable in the module called "aws_vpc.sandbox-vpc.id" However this only gives me ID, if I use a resource with many exported attributes, my code becomes very bloated with output variable declarations.

I searched the docs and I don't see any other usage. Also played around a little and got a bunch of errors trying to do what I'm stating.

[PetaPetaPeta]

I am not aware of any functionality to export entire resources.
I do understand your worry of your code becoming bloated. To reduce this issue I split each module into at least three files for to maintain structure:

1. main.tf: The purpose of this file is to instantiate all resources. Can be split across several files if necessary.
2. variables.tf: Contains the variables used in the main.tf file
3. output.tf: Contains all the output variables of the module

By only defining output variables in your module you define a nice "interface" to your module that makes it easy to work with. Think of it as a class in a programming language. You do not want to expose every part of the class, but only a subset.

[apparentlymart]

This is not an immediate-term solution, but once #6819 is added this could be written something like this:

(THIS WILL NOT WORK YET, SINCE THAT PR ISN'T MERGED)

module "sandbox" {
    source = "./sandbox"
}

data "aws_vpc" "sandbox" {
    id = "${module.sandbox.aws_vpc.sandbox-vpc.id}"
}

resource "aws_internet_gateway" "ig01" {
    # This is of course pointless since you already knew the id,
    # but you could also use any other attribute of the `aws_vpc`
    # data source.
    vpc_id = "${data.aws_vpc.sandbox.id}"
}

This is not 100% ideal since it will cause Terraform to re-read a redundant copy of the VPC data from the EC2 API, rather than just exposing what was already created inside the module. However, it would allow you achieve what you want to achieve here.

[ldelossa01]

@PetaPetaPeta Do you have an example of your structure on github?

[jen20]

Hi @ldelossa01! This isn't supported right now - @apparentlymart's workaround is probably closest to being implementable. However, some changes made to the remote state data source in 0.7rc2 mean that this is not beyond the realms of possibility - previously it couldn't be done because of subtleties around the interaction of the helper/schema library. I'm going to go ahead and close this issue for now, but will circle back around to it once we have the RTM of 0.7 out the door, since I don't think it's a bad idea.

[ghost]

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