fix: adding support for opt-in regions and arm architecture

[stefano-franco]

Description of the change

This module cannot currently be used in opt-in regions (e.g. Zurich eu-central-2) where the Spacelift AMIs are not replicated.
Also when using a custom AMI via var.ami_id the module fails as the data source data.aws_ami.this always fails if there is no Spacelift AMI in the Spacelift AWS account (643313122712). Using data.aws_ami_ids.spacelift avoids this problem as the data source returns an empty list if the AMI does not exist. A lifecycle postcondition checks that an AMI was provided either with var.ami_id or by the data source.

When choosing an arm based instance type via var.ec2_instance_type the data source data.aws_ami.this will return a x86_64 AMI because it's hardcoded into the name_regex and filter. By adding the data.aws_ec2_instance_type.spacelift data source we can dynamically get the correct architecture for the Spacelift AMI. This allows to use the latest arm based Spacelift AMIs by default.

Type of change

• Bug fix (non-breaking change that fixes an issue);
• New feature (non-breaking change that adds functionality);
• Breaking change (fix or feature that would cause existing functionality to not work as expected);
• Documentation (a documentation or example fix not affecting the infrastructure managed by this module);

Checklists

Development

• All necessary variables have been defined, with defaults if applicable;
• The code is formatted properly;

Code review

• The module version is bumped accordingly;
• Spacelift tests are passing;
• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached;
• This pull request is no longer marked as "draft";
• Reviewers have been assigned;
• Changes have been reviewed by at least one other engineer;