Error when using lifecycle rule with null values

[GusAntoniassi]

Description

When trying to use a lifecycle rule while passing null values for transition, noncurrent_version_transition and filter inputs, Terraform throws a "null value has no attributes" error. I believe this is due to how the for_each blocks are implemented:

        for_each = try(flatten([rule.value.expiration]), [])

Since there is no compact, the flatten call will return [null] which is a valid list with one value.

In my case the null values are coming from a variable with optional fields, so it would be best if the module could handle null values correctly.

• ✋ I have searched the open/closed issues and my issue is not listed.

Versions

• Module version [Required]: 4.5.0

• Terraform version: 1.7.5

• Provider version(s): 5.84.0

Reproduction Code [Required]

module "s3_bucket" {
  source = "terraform-aws-modules/s3-bucket/aws"

  bucket = "tftest-foobar-bucket"

  lifecycle_rule = [
    {
      id      = "foobar"
      enabled = true

      expiration = null

      transition = null

      noncurrent_version_expiration = null

      noncurrent_version_transition = null

      filter = {
        tags = null
      }
    }
  ]
}

Steps to reproduce the behavior:

• run terraform plan

Expected behavior

The plan to create a bucket with an empty lifecycle rule.

Actual behavior

Error:

│ Error: Attempt to get attribute from null value
│ 
│   on .terraform/modules/s3_bucket/main.tf line 281, in resource "aws_s3_bucket_lifecycle_configuration" "this":
│  281:           storage_class = transition.value.storage_class
│     ├────────────────
│     │ transition.value is null
│ 
│ This value is null, so it does not have any attributes.
╵
╷
│ Error: Attempt to get attribute from null value
│ 
│   on .terraform/modules/s3_bucket/main.tf line 302, in resource "aws_s3_bucket_lifecycle_configuration" "this":
│  302:           storage_class             = noncurrent_version_transition.value.storage_class
│     ├────────────────
│     │ noncurrent_version_transition.value is null
│ 
│ This value is null, so it does not have any attributes.
╵
╷
│ Error: Invalid function argument
│ 
│   on .terraform/modules/s3_bucket/main.tf line 317, in resource "aws_s3_bucket_lifecycle_configuration" "this":
│  317:         for_each = [for v in try(flatten([rule.value.filter]), []) : v if max(length(keys(v)), length(try(rule.value.filter.tags, rule.value.filter.tag, []))) == 1]
│ 
│ Invalid value for "inputMap" parameter: argument must not be null.
╵
╷
│ Error: Invalid function argument
│ 
│   on .terraform/modules/s3_bucket/main.tf line 337, in resource "aws_s3_bucket_lifecycle_configuration" "this":
│  337:         for_each = [for v in try(flatten([rule.value.filter]), []) : v if max(length(keys(v)), length(try(rule.value.filter.tags, rule.value.filter.tag, []))) > 1]
│ 
│ Invalid value for "inputMap" parameter: argument must not be null.

[github-actions]

This issue has been automatically marked as stale because it has been open 30 days
with no activity. Remove stale label or comment or this issue will be closed in 10 days

[GusAntoniassi]

Remove stale label

[github-actions]

This issue has been automatically marked as stale because it has been open 30 days
with no activity. Remove stale label or comment or this issue will be closed in 10 days

[GusAntoniassi]

Hi @antonbabenko any thoughts on this?

[antonbabenko]

@GusAntoniassi This looks pretty good. I currently don't have time to run the examples and verify a few cases. Hopefully, I will be able to do it in the near future.

[antonbabenko]

While we are not going to have this feature implemented in the module like you suggested in #309, you still can filter out null values like this:

locals {
  lifecycle_rule = {
      id      = "foobar"
      enabled = true

      expiration = null

      transition = null

      noncurrent_version_expiration = null

      noncurrent_version_transition = null

      filter = {
        tags = null
      }
    }

  filtered_lifecycle_rule = {
    for k, v in local.lifecycle_rule: k => v if v != null
  }
}

###

module "s3_bucket" {
  source = "terraform-aws-modules/s3-bucket/aws"

  bucket = "tftest-foobar-bucket"

  lifecycle_rule = [ local.filtered_lifecycle_rule ]
}

[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.