Add required_version functionality like tfenv

[BrianMusson]

Hi, can you add support for required_version like https://github.com/tfutils/tfenv#min-required

Thanks!

[tdorrodt]

@BrianMusson, not sure this repo is getting much attention from its owner. However, I'm attempting to keep it moving forward under my own fork.

I'm currently making updates to my fork to catch up with the latest changes in tfenv and was looking at the min-required feature.

I don't believe what you are requesting is currently possible until terragrunt supports a required_version feature or something similar. You might considering weighing in on that linked issue (#182) to express support.

I'm currently using terraform 0.12.2 and terragrunt 0.19.2, and thought I'd run a quick test to see what I might be able to get away with. I attempted to set an arbitrary argument, terragrunt_version = ">=0.19.4" (consistent with the most recent comments in the issue linked above), in my terragrunt.hcl file and then ran the terragrunt executable. Unfortunately, it complained: "Unsupported argument; An argument named "terragrunt_version" is not expected here".

If you have any thoughts on how to implement your request, I'm willing to consider and take a crack at it under my fork. Otherwise, its a waiting game on terragrunt and, unfortunately, I don't have the cycles to contribute to that #182 issue at the moment.

Cheers.

[ruionwriting]

I'm currently making updates to my fork to catch up with the latest changes in tfenv and was looking at the min-required feature.

On my use case I simply want to auto-detect terraform_version.

So tfenv min-required equivalent tgenv min-required might not be a bad name for it. Open for discussion and contributing even Bash not being my thing :D.