Cannot use module variables in parent .tf

[pplanel]

My folder structure:
-- proj
--- main.tf
--- vpc
---- vpc.tf
---- variables.tf
I'm trying to use the public_subnets and the default_security_group_id output variables in my main.tf.
My module declaration is this:
module "myModule" {
and in my instance im trying to use like this:
vpc_security_groups_ids = "${module.myModule.default_security_group_id}"
but when i run terraform plan
it yields the follow:
resource 'aws_instance.bastion' config: unknown module referenced: myModule

[antonbabenko]

Check source argument inside module "myModule" in your main.tf. It should be like source="./vpc".

Make sure that you run terraform get or terraform init before running plan.

If this doesn't help, please show more of your main.tf