r/aws_emr_cluster: bootstrap_action.args empty string value not sent to AWS

[ewbankkit]

terraform apply this configuration:

resource "aws_emr_cluster" "test" {
  bootstrap_action {
    path = "s3://${aws_s3_object.testobject.bucket}/${aws_s3_object.testobject.key}"
    name = "test"

    args = ["1",
      "",
      "3"
    ]
  }
}

A subsequent terraform plan shows a diff:

~ bootstrap_action {
          ~ args = [ # forces replacement
                "1",
              + "",
                "3",
            ]

terraform-provider-aws/internal/flex/flex.go

Lines 23 to 32 in 5c820cd

	func ExpandStringList(configured []interface{}) []*string {
	vs := make([]*string, 0, len(configured))
	for _, v := range configured {
	val, ok := v.(string)
	if ok && val != "" {
	vs = append(vs, aws.String(v.(string)))
	}
	}
	return vs
	}

[github-actions]

Community Note

Voting for Prioritization

• Please vote on this issue by adding a 👍 reaction to the original post to help the community and maintainers prioritize this request.
• Please see our prioritization guide for information on how we prioritize.
• Please do not leave "+1" or other comments that do not add relevant new information or questions, they generate extra noise for issue followers and do not help prioritize the request.

Volunteering to Work on This Issue

• If you are interested in working on this issue, please leave a comment.
• If this would be your first contribution, please review the contribution guide.

[ewbankkit]

Testing a modified version of the resource that does send the empty string ("") values to the AWS API still results in a diff as the DescribeCluster call returns the bootstrap action arguments without the empty string.
I have verified that if an empty string really does need to be passed to the bootstrap script

    args = ["1",
      "\"\"",
      "3"
    ]

works.

[YakDriver]

Terraform takes the empty string in the args []interface{} as nil. In other words, an empty args in the config becomes a nil that is !ok in if v, ok := v.(string); ok {.

[github-actions]

This functionality has been released in v5.12.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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 have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.