Support .terraform-version for Terraform

[suzuki-shunsuke]

Feature Overview

Support .terraform-version for Terraform.

Why is the feature needed?

• To make it easy to migrate other version managers to aqua.
• To enable developers to use aqua and other version managers

.terraform-version is a common version file for Terraform.

Workaround

No response

Example Code

No response

Note

• https://github.com/aquaproj/aqua/issues/3061
• https://github.com/aquaproj/aqua/issues/3183

[suzuki-shunsuke]

One of issues is where aqua gets the information about Terraform. aqua usually gets it from registry, but .terraform-version doesn't have any reference to aqua registry. There are some options.

1. Hardcode to aqua: If aqua-registry setting for Terraform is unstable, every time it is changed we need to release aqua. It's undesirable
2. Hardcode aqua-registry version in aqua: This is really same with the option 1
3. Use the latest installed aqua-registry : This is implicit and depends on the state of the machine. This is not declarative
4. Find aqua.yaml and get aqua-registry from it: This doesn't work if aqua.yaml isn't found

I guess many Terraform version managers don't have the concept registry and accept the option 1. I think Terraform setting is stable and would not be changed so frequently.

But there are several version files like .terraform-version.

• .terraform-version
• .node-version
• .nvmrc
• etc

Do we need to hardcode all of them into aqua? It's undesirable.

[suzuki-shunsuke]

• aqua i finds .terraform-version and install Terraform
• If terraform executes, aqua searches aqua.yaml and .terraform-version. If aqua finds .terraform-version first or Terraform isn'f found in aqua.yaml, aqua uses .terraform-version
• aqua list -i outputs terraform if .terraform-version exists