Add Blacklisting to aws_availability_zones Data Source

[bflad]

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Description

The aws_availability_zones data source is great for creating reusable Terraform configurations across AWS Regions. There are a few use cases where it might make sense to purposefully blacklist certain Availability Zones by name or zone ID.

Use Case 1: New Availability Zone Launches

When AWS adds a new Availability Zone, there is an increasing possibility that all services and functionality might not be available from day 1. Providing a blacklist is a quick way to prevent initial provisioning issues until all functionality can be verified.

Use Case 2: Known Missing Availability Zone Features

While all Availability Zones across a Region are generally similar, there have been observed cases where this is not true. Many AWS service APIs do not have a query for whether specific functionality exists per Availability Zone. e.g.

• Missing EC2 Instance types
• No EC2 Transit Gateway support

Use Case 3: Colocation of Services

Infrastructures may be using Availability Zone IDs to colocate networking for speed or reduction in inter-AZ data transfer costs.

Use Case 4: Purchased Availability Zone Reserved Capacity

Certain AWS services allow purchasing reserved capacity at a discounted price. Some of these reservations are based on Availability Zone.

Affected Data Source

• aws_availability_zones

Potential Terraform Configuration

data "aws_availability_zones" "by_name" {
  blacklisted_names = ["us-west-2d"]
}

data "aws_availability_zones" "by_zone_id" {
  blacklisted_zone_ids = ["usw2-az4"]
}

[nywilken]

The enhancement to the aws_availability_zones data source has been merged and will be released with version 2.9.0 of the Terraform AWS provider.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!