fix: update parameter group to fix name vs. name_prefix

[bryantbiggs]

Description

• remove 2nd resource in parameter_group sub-module and instead use a variable flag to determine whether or not to use a unique prefix on the name; this matches what was done in the option_group sub-module
• remove use of var.identifier from sub-module and instead rely on var.parameter_group_name provided
• update example/option-groups -> option/groups to test/validate changes to option and parameter groups outside of creating RDS instances

Motivation and Context

• working towards consistent use of name versus name_prefix for the sub-modules as well as the root module (subnet group will be next and last update required now that option group is done + this PR)

Relates to #121

Breaking Changes

yes; albeit minor since again, parameter groups can be re-created without disruption (create_before_destroy is used here)

For users who are looking to upgrade, they will need to perform the following changes if they wish to forgo the re-creation:

If using without the name-prefix for parameter groups:

• terraform state mv module.<your_module_name>.db_parameter_group.this_no_prefix module.<your_module_name>.db_parameter_group.this

How Has This Been Tested?

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

[antonbabenko]

v2.25.0 has been just released.

[atrakic]

I didn't have much time to see why CI failed all of sudden so as quick fix, I've ended up to pin version = "2.23.0". Hope it helps to somebody.

[atrakic]

BTW: Just tried to bump to latest version with option: create_db_option_group = false but after removing state:

terraform get
terraform state rm "module.rds.module.db_option_group.aws_db_option_group.this[0]"

my run ends with:

Error: Error in function call

  on .terraform/modules/rds/main.tf line 8, in locals:
   8:   option_group           = var.engine != "postgres" ? coalesce(module.db_option_group.this_db_option_group_id, var.option_group_name) : null
    |----------------
    | module.db_option_group.this_db_option_group_id is ""
    | var.option_group_name is ""

Call to function "coalesce" failed: no non-null, non-empty-string arguments.


Error: first character of parameter group "name_prefix" must be a letter

  on .terraform/modules/rds/modules/db_parameter_group/main.tf line 12, in resource "aws_db_parameter_group" "this":
  12:   name_prefix = local.name_prefix

Comment: coalesce() supports default values, maybe should be used here?

[bryantbiggs]

hi @atrakic, I have opened a PR that should do two things that have been identified:

• if you do not provide a name for the option group or parameter group, it will default back to the previous default of ${var.identifier}-
• if you elect to not create an option group or parameter group, nor provide a name of an existing option/parameter group - it will default to pulling the default groups provided by AWS

I've updated the two examples to show and validate this
#308

[atrakic]

@bryantbiggs Yes, after second attempt I was able to bump to latest with:

...
create_db_subnet_group = true ## already created and runs, leave it as it is
  parameters = [
    {
      name  = "character_set_client"
      value = "utf8"
    },
    {
      name  = "character_set_server"
      value = "utf8"
    }
  ]

  options = [
    {
      option_name = "MARIADB_AUDIT_PLUGIN"

      option_settings = [
        {
          name  = "SERVER_AUDIT_EVENTS"
          value = "CONNECT"
        },
        {
          name  = "SERVER_AUDIT_FILE_ROTATIONS"
          value = "37"
        },
      ]
    },
  ]

[github-actions]

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