aws_db_parameter_group parameter updates not working in v2

[jamesmharvey]

Note: this is the same issue as #13551 . This is a request to add it the fix, #12112 , as a point release in the v2.x.x series, due to the number of breaking changes in v3.0.0

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Terraform CLI and Terraform AWS Provider Version

Terraform v0.12.26

• provider.aws 2.70.0

Affected Resource(s)

• aws_db_parameter_group

Terraform Configuration Files

resource "aws_db_parameter_group" "postgres_10" {
  name        = "psql-pg-test-10"
  family      = "postgres10"
  description = "Postgres parameter group test"

  lifecycle {
    create_before_destroy = true
  }

  parameter {
    name         = "rds.pg_stat_ramdisk_size"
    value        = 256
    apply_method = "pending-reboot"
  }
}

Debug Output

Panic Output

N/A

Expected Behavior

Parameter group value is updated

Actual Behavior

Parameter group remains the same

The plan output looks like this:

      - parameter {
          - apply_method = "pending-reboot" -> null
          - name         = "rds.pg_stat_ramdisk_size" -> null
          - value        = "0" -> null
        }
      + parameter {
          + apply_method = "pending-reboot"
          + name         = "rds.pg_stat_ramdisk_size"
          + value        = "256"
        }

Reading the code, it sees this a removal of an old parameter and the addition of a new parameter, and then modifies the parameter group with the new value, and then resets the old parameter back to the existing value. Even swapping the order of those two operations would likely fix this issue

Steps to Reproduce

1. Create an empty parameter group using terraform
2. Update the parameter group to use rds.pg_stat_ramdisk_size = 256

Important Factoids

This has already been fixed in v3.3.0, but due to the number of breaking changes in v3.0.0, it's difficult to migrate from 2.70.0 to 3.0.0. This is a request to release a pointfix to 2.70.0 with the fix to this issue.

I realize this is a long shot, but I figured it's worth asking.

References

[sutharshan-sharma]

As @amesmharvey said upgrading to v3.3.0 cause many breaks + not all the modules are supported v.3.3.0
Better if this get fixed in 2.70.0 provider version

[sulabhk]

We use provider v2.62 currently and do not want to unnecessarily migrate to 3.x given the added preparation and analysis required to get there. This should ideally have been working for 2.x too.

[gdavison]

Hi @jamesmharvey, @sutharshan-sharma, @sulabhk. In general, our policy is to make fixes and add new features to the current version. We understand this isn't ideal, but unfortunately we don't currently have the capacity to maintain multiple versions of the provider at the same time. We've recently updated our FAQ to capture this.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!