Suppport -backend-config and/or optional script dir with terraform workspace commands

[benfortuna]

Current Terraform Version

$ terraform -v
Terraform v0.12.0

Use-cases

Currently I can run terraform init -backend-config=<path> [dir] that allows me to separate the local state/backend config vars from the terraform provisioning scripts (including partial backend config).

However I cannot use terraform workspaces with this configuration as (I believe) it currently requires the state/backend config vars to be in the same directory as the terraform scripts. If I do use terraform workspace new it will give the error:

Backend reinitialization required..
Reason: Unsetting the previously set backend..

Attempted Solutions

I've explore available environment variables but there doesn't seem to be any global way to set additional backend-config. Also I think the optional directory for terraform scripts should be explicitly added to the command itself.

Other commands such as terraform state allow state to exist in another directory via: terraform state <subcommand> -state <path>, however this option is already used to copy old state to a new workspace, and it also may not work considering workspaces are using multiple state files.

Many commands support optional directory for terraform scripts, which may be easiest to implement for the workspace commands: e.g. terraform plan <scripts_dir>.

Proposal

Add the -backend-config and/or optional scripts directory to terraform workspace commands to allow separation of state/config: terraform workspace new -backend-config <path> [dir]

References