fix: add variable to exclude ai zones from available zones

[lennydong-rogo]

As noted in: hashicorp/terraform-provider-google#25914

It seems the GCP API for returning compute zones began returning ai zones, as a result of the recent introduction of AI zones on 16th Jan in us-central1

This PR adds a variable to allow users to exclude AI zones when using the GKE module

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[gemini-code-assist]

Summary of Changes

Hello @lennydong-rogo, 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 introduces a new optional variable, exclude_ai_zones, to the GKE module. This variable allows users to explicitly filter out newly introduced AI-specific compute zones from the list of available zones dynamically fetched from Google Cloud. This ensures that GKE deployments can maintain expected zone configurations and avoid unintended interactions with AI zones, addressing a recent change in the GCP API's zone enumeration.

Highlights

• New Configuration Variable: Introduced an optional boolean variable exclude_ai_zones (default false) to control the inclusion of AI-specific zones when fetching available Google Compute Zones.
• Conditional Zone Filtering: Implemented logic in main.tf to conditionally filter out zones matching the regex pattern -ai\d+[a-z]$ from the list of available zones if exclude_ai_zones is set to true.
• Addressing GCP API Changes: This change addresses a recent issue where the GCP API began returning AI zones, which could inadvertently affect GKE module deployments by including unintended zones.

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[gemini-code-assist]

Code Review

This pull request introduces a new variable exclude_ai_zones to filter out AI-specific zones from the list of available zones, which is a good fix for the issue described.

However, the changes have been applied to auto-generated files (main.tf and variables.tf) instead of their source templates in the autogen/main/ directory. This is a critical issue as the changes will be lost during the next code generation. I've left comments on the respective files with instructions on how to apply the changes to the correct template files.

I've also included a suggestion to improve the clarity of the filtering logic.

[gemini-code-assist]

This file is auto-generated from a template. Your changes will be overwritten. Please apply your changes to the template file autogen/main/main.tf.tmpl instead.

You should replace the random_shuffle.available_zones resource in autogen/main/main.tf.tmpl with the logic you've added.

While you're at it, I'd also suggest using regexall for better readability. The !can(regex(...)) pattern works, but it's a bit of a trick that relies on regex erroring on no match. Using length(regexall(...)) == 0 is more explicit about the intent.

Here is the suggested replacement for the random_shuffle resource in autogen/main/main.tf.tmpl:

resource "random_shuffle" "available_zones" {
  count        = local.zone_count == 0 ? 1 : 0

  input = var.exclude_ai_zones ? [
    for zone in data.google_compute_zones.available[0].names : zone
    if length(regexall("-ai\\d+[a-z]$", zone)) == 0
  ] : data.google_compute_zones.available[0].names
  result_count = 3
}

[gemini-code-assist]

This file is auto-generated from a template. Your changes will be overwritten. Please add the new exclude_ai_zones variable to the template file autogen/main/variables.tf.tmpl instead. Here is the suggested addition for autogen/main/variables.tf.tmpl:

variable "exclude_ai_zones" {
  description = "(Optional) Controls whether to exclude AI zones from the dynamically fetched google_compute_zones"
  type        = bool
  default     = false
}