Helper function to load tfvars into environment variables

[raymondbutcher]

In the workspace example it mirrors (symlinks) a tfvars file into the current directory so it will get loaded automatically (and the other files in the params dir won't get loaded).

pretf/examples/workspaces/pretf.workflow.py

Lines 25 to 27 in 77ef2f6

	created = workflow.mirror_files(
	"../stack.tf.py", f"../../params/{stack}.{workspace}.auto.tfvars"
	)

This symlink could be avoided by parsing the file and exporting TF_VAR_* environment variables for each value found in the file.

This would be a work around for Terraform not being able to load tfvars per workspace and perhaps other use cases I haven't thought of. Maybe people just prefer their params to be sitting together in a separate directory, I don't know.

Usage might be like this:

workflow.export_variables_from_file(f"{terraform.workspace}.workspace.tfvars")