BREAKING CHANGE: update module to allow for control over individual cluster instances and latest features

[bryantbiggs]

Description

See UPGRADE-6.0.md for full list of changes, updates, etc.

• Added create_db_subnet_group variable to control whether a DB subnet group is created or not; previously if db_subnet_group_name was specified then an existing subnet group was used. Now the combination of create_db_subnet_group and db_subnet_group_name determine the name of the subnet group AND whether to create anew or use existing
• Minimum version of AWS provider increased to v3.63.0 to support features added
• Added random_password_length to give users control over the length of the random password that can be created; defaults to prior existing value of 10
• Local variable check added on aws_rds_cluster for attributes database_name, master_username and master_pass to support secondary clusters (global cluster, replication cluster, etc.)
• Conditional creation check for is_serverless added to aws_rds_cluster_instance, aws_appautoscaling_target, and aws_appautoscaling_policy since these are not applicable for serverless clusters
• Added availability_zone, copy_tags_to_snapshot attributes to aws_rds_cluster_instance which are now accessible via the instances map
• Removed engine_version from aws_rds_cluster_instance lifecycle ignore block now that this has been patched in upstream AWS provider
• New resource aws_rds_cluster_endpoint added to allow for creation of custom, additional endpoints
• New resource aws_rds_cluster_role_association added to allow for association IAM roles with the cluster
• Where applicable, variable default values have been set to null to use upstream AWS provider default values
• Update variable descriptions from upstream provider docs

List of backwards incompatible changes

• Coalesce of previous, default IAM enhanced monitoring role name has been removed (this was marked as a TODO to remove at next breaking change)
• Name tag removed from DB subnet group and enhanced monitoring role; the name is now set by the provider resource and this is no longer necessary
• iam_roles removed from aws_rds_cluster resource with the addition of aws_rds_cluster_role_association; per the docs this will cause conflicts and only one should be used and the role association resource contains more functionality/features
• replication_source_identifier added to aws_rds_cluster ignore lifecycle block to support secondary, replication clusters per the docs
• global_cluster_identifier added to aws_rds_clsuter ignore lifecycle block to support global clusters per the docs
• replica_countreplaced with instances; instances are now controlled by a map of maps, allowing users to create a homogenous cluster or a heterogenous cluster with fine grain control over the instances provisioned through the use of the new map attributes. This means the aws_rds_cluster_instance no longer uses count and now uses for_each for better stability and isolated change control.
• iam_roles variable has been re-purposed from a list of IAM roles to associate with the cluster via the aws_rds_cluster resource and instead is now a map of maps to associate roles via the new aws_rds_cluster_role_association resource
• aws_appautoscaling_target resource identifier changed from read_replica_count to this to follow conventions. This change requires either re-creation or a Terraform state rename to avoid disruption (see below)

Motivation and Context

Closes #105
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Breaking Changes

• Yes, see UPGRADE-6.0.md

How Has This Been Tested?

• I have tested and validated these changes using ALL of the examples in examples/*

[bryantbiggs]

@antonbabenko I still need to finish up the state move commands for the migration doc, and something seems to have changed that causes the s3 import example to not complete - but wanted to open it up a bit early to get any feedback while I finish it up

[bryantbiggs]

ok this should be ready for review if you get some time @antonbabenko 🙏🏽

[antonbabenko]

Looks pretty good. Should I merge it and cut a major release? Or is there anything else remaining to be done before the merge?

[bryantbiggs]

nothing else to add at this time, re-confirmed the examples this morning and also verified the state move commands - should be all set to cut the major release. I'll keep any eye on any issues if they pop up

[antonbabenko]

Here we go! 🎉

v6.0.0 has been just released.

[github-actions]

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