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UPGRADE-4.0.md

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Upgrade from v3.x to v4.x

If you have any questions regarding this upgrade process, please consult the examples/ projects:

If you find a bug, please open an issue with supporting configuration to reproduce.

List of backwards incompatible changes

  • Support for Terraform <=v0.12.x has been dropped; v0.13.1 is now the minimum supported version
  • Terraform AWS provider minimum version is now v4.0.0 in order to support the replacement of var.name(deprecated) for var.db_name
  • Separate RDS instance resource for MSSQL/SQLServer has been removed - all engines are supported under one resource
  • storage_encrypted is now set to true by default; was previously false
  • create_random_password is now set to true by default; was previously false
  • create_db_subnet_group is now set to false by default; was previously true; typically a shared DB subnet group will be used, most likely from the VPC module
  • random_password_length is now set to 16 by default, was previously 10
  • Random provider minimum version supported is now v3.1.0
  • final_snapshot_identifier no longer coalesces var.final_snapshot_identifier and instead relies on var.final_snapshot_identifier_prefix with a random suffix to avoid name collisions

Additional changes

Added

  • latest_restorable_time added to ignored changes
  • replica_mode support added to DB instance

Modified

  • username, password, and engine are set to null when a replicate_source_db or snapshot_identifier is provided; these values are already provided in the respective source
  • engine_version is set to null when a value is provided for replicate_source_db
  • db_subnet_group_name has been updated to use full name when prefix is enabled
  • Name tag removed from instance resource; name is set via identifier and not through tags; users can add back into the tags they provide if desired
  • Outputs have been updated to use try() syntax; local variable usage has been removed within outputs
  • engine, major_engine_version, family, password, db_subnet_group_name,db_subnet_group_description,parameter_group_name, parameter_group_description, option_group_name, option_group_description is now set to null by default; was previously ""
  • timeouts is now set to {} by default; was previously a copy+paste of default value used by provider. This is a no-op but will show up in plans as a diff

Variable and output changes

  1. Removed variables:

    • final_snapshot_identifier

  2. Renamed variables:

    • name (deprecated) -> db_name
    • master_password -> password

  3. Added variables:

    • replica_mode

  4. Removed outputs:

    • None

  5. Renamed outputs:

    • db_instance_master_password -> db_instance_password

  6. Added outputs:

    • None

Upgrade Migrations

The following examples demonstrate some of the changes that users can elect to make to avoid any potential disruptions when upgrading.

Before 3.x Example

module "rds" {
  source  = "terraform-aws-modules/rds/aws"
  version = "~> 3.0"

  master_password = "MySuperStrongPassword!"

  # Previously on read-replicas or restored from snapshot instances you needed to explicitly set these to null
  # These can now be safely removed and instead on the module to resolve these appropriately
  username = null
  password = null
  engine   = null
}

After 4.x Example

module "asg" {
  source  = "terraform-aws-modules/rds/aws"
  version = "~> 4.0"

  password               = "MySuperStrongPassword!"
  # Set random password creation to false if providing your own password as input
  create_random_password = false

  # If you did not have storage encrypted in `v3.x`, you can explicitly disable in `v4.x` to avoid disruption
  storage_encrypted = false
}

MSSQL/SQLServer

For MSSSQL/SQLServer, users will want to rename the resource in their Terraform state to align with the flattened DB instance resource module in v4.x:

terraform state mv 'module.<module-name>.module.db_instance.aws_db_instance.this_mssql[0]' 'module.<module-name>.module.db_instance.aws_db_instance.this[0]'

Where <module-name> is the name of your module definition.