feat(controller): expose controller IG and named ports for LB integration

[mangal390]

Description

This PR enhances the schedmd-slurm-gcp-v6-controller module by natively exposing the Managed Instance Group (MIG) and its named ports, allowing users to seamlessly integrate the controller with Google Cloud Load Balancers (such as Internal Passthrough or Internal Application LBs).

Changes made:

1. Added named_ports variable: Added an optional named_ports list variable to variables_controller_instance.tf which applies directly to the underlying google_compute_instance_group_manager / google_compute_region_instance_group_manager.
2. Updated Controller MIGs: Added a dynamic "named_port" block iterating over the new variable so users can expose ports (example: slurm-restapi: 6820) for Load Balancer backend discovery.
3. Exposed MIG Outputs: Added standard outputs to outputs.tf (controller_instance_group, controller_mig_name, controller_mig_id, and controller_instance_names) that output the self-links and IDs of the deployed MIG when HA is enabled.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the schedmd-slurm-gcp-v6-controller module by providing native support for named ports on the controller's Managed Instance Group. This change enables seamless integration with various Google Cloud Load Balancer configurations. Additionally, it exposes several key infrastructure identifiers as outputs, improving the observability and manageability of the deployed controller resources.

Highlights

• Named Ports Configuration: Introduced a new named_ports variable to allow users to define named ports for the controller Managed Instance Group (MIG), facilitating easier integration with Google Cloud Load Balancers.
• MIG Integration: Updated both zonal and regional controller MIG configurations to dynamically apply the named_ports settings.
• Enhanced Outputs: Exposed new outputs including controller_instance_group, controller_mig_name, controller_mig_id, and controller_instance_names to improve visibility into the deployed infrastructure.

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[gemini-code-assist]

Code Review

This pull request introduces a new named_ports input variable to the Slurm GCP v6 controller module, dynamically applying these ports to both zonal and regional controller managed instance groups. It also adds several outputs to expose details about the controller instance groups. The review feedback recommends replacing the try() function in the new outputs with one(concat(...)) to avoid masking configuration errors, and adding input validation to the named_ports variable to ensure valid port numbers and RFC 1035 compliant names.

[arpit974]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a new named_ports input variable to the Slurm GCP v6 controller module, enabling the configuration of named ports on the controller's zonal and regional Managed Instance Groups (MIGs). It also adds several outputs to expose MIG details and updates the module's documentation. The review feedback recommends referencing the MIG resources directly in the controller_mig_name output to preserve Terraform's dependency graph, and adding a validation rule to ensure all named port names are unique to prevent API errors.

[mangal390]

@arpit974 - I have resolved the conflicts and update the validation block.