Replace null_resource with terraform_data

[janfrederik]

As from Terraform 1.4, the doc suggests to use terraform_data instead of null_resource. See https://registry.terraform.io/providers/hashicorp/null/latest/docs/resources/resource.

To avoid destroy and recreation of these resources, terraform>=1.9 allows the moved statement to do exactly this refactoring. Works like a charm :-)

For details, see https://registry.terraform.io/providers/hashicorp/null/latest/docs/guides/terraform-migration#migrating-existing-configurations.

[mysticaltech]

@janfrederik Your issue has been accepted last week, so great job! Going to review in-depth.

[mysticaltech]

Code Review

Overall, this PR cleanly replaces null_resource with the new terraform_data resource. The approach is consistent throughout, using triggers_replace to force a new evaluation when relevant data changes. The added moved blocks ensure a smooth migration of state, and the mapping from null_resource to terraform_data looks thoughtfully handled.

Key Observations

1. terraform_data Resource Semantics: The terraform_data resource is designed for ephemeral data or orchestration placeholders. Using it as a direct replacement for null_resource is valid, and the usage looks consistent with typical patterns of triggers and provisioning logic.
2. State & Orchestration: You are storing some relatively large sets of triggers (like checksums) in yamlencode(...). That is typical for null_resource migrations but keep in mind that changes in large dynamic strings can lead to more frequent replacements. This is expected, but be sure that is the intended orchestration flow.
3. Use of Moved Blocks: Excellent approach to preserve state (moved { from = null_resource.foo to = terraform_data.foo }) so existing resources do not get recreated inadvertently.
4. No Obvious Performance or Security Gaps: The code remains consistent with prior state. The references to sets, triggers, and inline provisioning look properly aligned.

Recommendation: The changes look good overall. Great work on systematically replacing these resources!

[mysticaltech]

I'm ready to merge when you are, let me know @janfrederik

[janfrederik]

I'm ready to merge when you are, let me know @janfrederik

Hi @mysticaltech
I just updated with the latest code from main and fixed a null_resource that I had forgotten.

Still waiting for the release of opentofu 1.10 with the support for moving null_resource to terraform_data. The code has already been committed to opentofu's main branch (see PR opentofu/opentofu#2481), so now we just need a little patience for the release.

[mysticaltech]

Ok wonderful, thanks