improvement: Introduce wg_tags to handle default_tags on provider level

[kbcz1989]

PR o'clock

closes: #1578, #1455(?), #1248(?)

Description

When default_tags are used on aws provider level, and the same tags are defined as input to this module, we end up with this issue:
default_tags always shows an update

If "tags" var is not set, no tags will be applied to resources which defines tag_specification.

So, either we have default_tags and do not set "tags". which leaves us with "empty" tag_specifications or we don't use default_tags.

This PR introduces new variable "wg_tags", which will be used on resources which define dynamic tags/tag_specifications if "tags" is not set. Backward compatibility is therefore fully retained.

There will be changes only if wg_tags is set, otherwise the module works the same as before.

Checklist

• README.md has been updated after any changes to variables and outputs. See https://github.com/terraform-aws-modules/terraform-aws-eks/#doc-generation

[daroga0002]

what is difference between input_wg_tags and arleady existing tags input?

[kbcz1989]

what is difference between input_wg_tags and arleady existing tags input?

Hello @daroga0002. If you have default_tags set on provider level, those will be applied to all resources, except for the "tag_spefications" and "dynamic "tag"" attributes of certain resources, where they rely on having "tags" set. Currently there is no way to apply "default_tags" and "tags" to this module without ending up with everlasting changes detected.

wg_tags would only be applied to "tag_specifications" and dynamic "tag" resources, which are otherwise unmanaged by default_tags, if they are set.

There actually should be no difference between wg_tags and tags in most situations. But if you want to move tags to default_tags on provider level, there is a discrepancy.

[daroga0002]

there is a discrepancy.

what exactly? could you show plan diff here?

[kbcz1989]

  # module.eks_main.aws_autoscaling_group.workers[0] will be updated in-place
  ~ resource "aws_autoscaling_group" "workers" {
        id                        = "<REDACTED>"
        name                      = "<REDACTED>"
        # (24 unchanged attributes hidden)

      - tag {
          - key                 = "some_key" -> null
          - propagate_at_launch = true -> null
          - value               = "some_value" -> null
        }
        # (4 unchanged blocks hidden)
    }
  # module.eks_main.aws_launch_template.workers_launch_template[0] will be updated in-place
  ~ resource "aws_launch_template" "workers_launch_template" {
        id                      = "<REDACTED>"
      ~ latest_version          = 12 -> (known after apply)
        name                    = "<REDACTED>"
      ~ tag_specifications {
          ~ tags          = {
              - "some_key" = "some_value" -> null
                # (1 unchanged element hidden)
            }
            # (1 unchanged attribute hidden)
        }
      ~ tag_specifications {
          ~ tags          = {
              - "some_key" = "some_value" -> null
                # (1 unchanged element hidden)
            }
            # (1 unchanged attribute hidden)
        }
        # (7 unchanged blocks hidden)
    }

if you want to use default_tags, in simplest case you would move anything you currently use in var.tags to default_tags.
Next TF run will apply default_tags on provider level to all resources, except in these dynamically-set attributes.
In these attributes, tags will be removed because var.tags is not set.

If you do set var.tags with same values as in default_tags, there will be changes detected on each run.

[daroga0002]

seems be common provider error, for example:
hashicorp/terraform-provider-aws#19188
hashicorp/terraform-provider-aws#19387

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[hatemosphere]

@antonbabenko this is actually quite important with the current behaviour of the AWS provider's default tags. we had to disable the usage of default tags in TF state with this module due to not having the ability to set non-default tags only on tag_specifications and dynamic tag resources

[antonbabenko]

If anyone wants to work on this one, please check this PR (around data source aws_default_tags) - https://github.com/terraform-aws-modules/terraform-aws-autoscaling/pull/169/files#diff-dc46acf24afd63ef8c556b77c126ccc6e578bc87e3aa09a931f33d9bf2532fbbR1

[kbcz1989]

The solution proposed by @antonbabenko is much better. I will close this PR and try to implement the proposed solution when I find some time.

[github-actions]

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