feat: add custom cluster endpoints

[cageyv]

Description

• Add cluster custom endpoints aws_rds_cluster_endpoint

Motivation and Context

• Using custom endpoints will help maintain the cluster
  • exclude the node from the custom endpoint
  • wait for all connections drained
  • maintain node without connections
  • add the node back to the endpoint

Aurora.Endpoints.Custom

How Has This Been Tested?

• I have tested and validated these changes using one or more of the provided examples/* projects

Additional info

READER type will be empty in case we run a single node cluster.
Because there are no readers. Just one writer node.

Endpoints will have enabled the option "Attach future instances added to this cluster" by default
Because there are no static_members and we ignore them for now

Future improvments

• static_members and excluded_members lists

[cageyv]

READER type will be empty in case we run a single node cluster.
Because there are no readers. Just one writer node.

Endpoints will have enabled the option "Attach future instances added to this cluster" by default
Because there are no static_members and we ignore them for now

[cageyv]

For outputs, I took the same design as for the VPC module

[cageyv]

@bryantbiggs @antonbabenko Anything else we need to add or describe?

[bryantbiggs]

I don't yet know what the ramifications of this are. we don't have these attributes set here, and yet we are ignoring them from future changes. we generally try to avoid the use of the ignore_changes lifecycle hook because it cannot be parameterized. I will have to do some tests to see what makes the most sense for this

[cageyv]

I'll do a couple of tests on my own. I am currently using this version and will check the behavior without ignoring

[cageyv]

We can use static_members for case then we need include only instances created by Terraform (by this module)
If we need reader endpoints only with nodes managed from iac.

And we can use excluded_members for case then we need exclude all instances created by this module.

By default both will be empty

var.cluster_custom_endpoints_only_static_members = false
var.cluster_custom_endpoints_all_excluded_members = false

[github-actions]

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