Terraform Version

Terraform v1.13.4
on darwin_arm64

Use Cases

• I have an internal module that sets up our basic application infrastructure and is used by a lot of apps. Occasionally I find I want to add an output and would like a way to have all the uses of the module output it too.
• For most projects, I create local modules and have multiple environments use it with different variable files. Each env has to output the module outputs.

Attempted Solutions

Currently I create an output for each module output in each app that uses it.

For local, I put the output blocks in a file then symbolic link it to each environment sub folder.

envs/
├─ dev/
│  ├─ outputs.tf -> ../outputs.tf
├─ prod/
│  ├─ outputs.tf -> ../outputs.tf
├─ outputs.tf

Could add the whole module as the output but that would require refactoring references to it.

Could use dynamic to loop through keys but still an extra step.

Proposal

Add a way to automatically pass outputs through from a module.

module "example" {
  source = "..."
  # default to false, True for all or list of keys
  propagate_outputs = "False | True | List(string)" 
}

This would be the equivalent of

output "output_id" {
    value = module.example.output_id
}

Pitfalls would be if two modules shared an output name or a module was used twice. For that a prefix could be added propagate_outputs_prefix = "example_" which would create:

output "example_output_id" {
    value = module.example.output_id
}

Otherwise, throw an error on conflicts on the validation stage.

References

No response