Support deploying some of the watson services in jp-tok region.

[vburckhardt]

Description

Use case: some customers want to deploy some of the watson services in jp-tok region.

Issue: currently, the location field is set to allow only the regions that are supported by ALL watson service.

2 approaches:

• In the location field - add all regions supported by at least one watson service. Add some static checks in the terraform logic to error out if the users selected to deploy a service in a region that is not supported
• Or, add an optional region input for each watson service

[andreainnocenti]

The cleanest way is to use this feature https://github.com/hashicorp/terraform/issues/25609 at plan time. Unfortunately terraform v1.9 is not yet available and we don't know when it will be avaliable in Schematics.

Let's do this with a check block https://developer.hashicorp.com/terraform/language/checks, do you agree?

[vburckhardt]

@andreainnocenti - here is an example of the way it is typically done with current version of terraform. https://github.com/terraform-ibm-modules/terraform-ibm-base-ocp-vpc/blob/05e504dbd0e3057171616ec98bfb9f96d7d45813/main.tf#L22

check block assertion cannot be applied here as they won't block execution (just surface a warning)

[mkrudele]

Before going ahead and implement, we must first understand if the watsonx platform works with services deployed in different regions, and which ones can be deployed in different regions.

[andreainnocenti]

Service	Regions
Watson Machine Learning	jp-tok,eu-gb,eu-de,us-south
Watson Studio	jp-tok,eu-gb,eu-de,us-south
watsonx.governance	eu-de,us-south
watsonx Assistant	au-syd,jp-tok,eu-gb,eu-de,us-south,us-east
Watson Discovery	au-syd,jp-tok,eu-gb,eu-de,us-south,us-east
watsonx.data	au-syd, jp-tok, eu-gb, eu-de, us-south
Cloud Object Storage	it must be in the same region of Watson Machine Learning
Key Protect	it must be in the same region of Watson Machine Learning

[andreainnocenti]

the final decision was to allow the regions jp-tok,eu-gb,eu-de,us-south and add a check on watsonx.governance

  lifecycle {
    precondition {
      condition     = contains(["eu-de", "us-south"], var.location)
      error_message = "watsonx.governance is only available in eu-de and us-south region."
    }
  }

in this way the plan fails