Generate HCL code for Terraform/OpenTofu

[mloskot]

The website says:

First, I've failed to find out in the documentation how I can trigger any transformation and output declarative code from the IaC in PKL. Is it possible to output the declarative code, code that simply shows desired state?

Second, it it looks like formae could quite easily, with using plugins, output IaC in other languages like JSON, HCL or even Bicep.
IMHO, it would be a significant selling point especially for users considering transition from Terraform/OpenTofu to formae.
Then, users could terraform plan using code generate by formae as a part of evaluation and double-check if their formae project is equivalent, what changes and actions to expect, etc.

[pavlobaron]

@mloskot thanks for opening this discussion!

Regarding the first topic: it reads like the extract command is what you are looking for. I suggest to look at its docs and the formae 101, it explains how we fit in different workflows.

Regarding the second topic: yes, this input/output schema flexibility is like that by design. I am very curious to explore your idea regarding transitioning from tf/Tofu.

We have not enabled JSON/YAML output schema on extract, since we consider extract an intermediate step - people extract resources as code, modify them to their liking and apply them back. Or update their own code from the reality, and then do a full reconcile.

Since we aren't supporting JSON or YAML as input schemas either (yet), the only available option in extract right now is Pkl. I can tell you that I know some community members already experiment with tasking Copilots / AI agents to translate our Pkl into something else. Pkl, especially flat Pkl the extract command generates, is totally simple for an LLM to digest / learn on the spot. And proper LLMs have tons of knowledge about tf and its AWS provider. So transitioning form our Pkl to HCL for AWS only using LLM could be a relatively straightforward path.

Maybe worth exploring for you?

Another option would be to look at the machine output of the inventory command. This one would give you some "raw" JSON and YAML that doesn't have the requirement to be re-applicable into formae, it's rather thought to output what will be processed by other tools. Maybe this is enough for that use case? I am still thinking it will need a strong middle man to translate from our inventory output into HCL, which brings us back to those LLMs..

Let us know if we are thinking in the right direction here, happy to continue the discussion!

[mloskot]

@pavlobaron

Regarding the first topic: it reads like the extract command is what you are looking for. I suggest to look at its docs and the formae 101, it explains how we fit in different workflows.

Yesterday, I spent almost an hour reading through the formae docs.

I had a feeling the extract command may be the one, but its documentation does not mention the word declarative or code anywhere. The docs just say it can be used for "extraction of a stack as forma". Although the docs explain what is stack and forma are, documentation of the forma concept does not even mention the word declarative. IMHO, it is not easy to connect the dots between the pitching slogans and the actual features. If documentation gives a room for interpretation, that is not helpful 🤷

If I come from the Terraform/OpenTofu world where declarative code was my daily bread and you sell me a new kind of bread, I need to be presented, explicitly and visually, with correspondence between the old bread and the new bread in order to grasp concepts of the new one. Otherwise, I cannot evaluate flavours of the new bread before I invest time to eat it. 😊

[pavlobaron]

@mloskot that is awesome, point totally taken! There is definitely room for improvement. Maybe once we have the maturity of other players who are in the business for like 8+ years we will have all the dots connected between messaging and the docs :)

"Declarative" might be also a hair split too often and too far from my point of view, as all terms in use have a fair amount of overlap anyway. But we will improve this one, thanks for the explanation 🙌

[mloskot]

@pavlobaron Thank you for the discussion and clarifications so far.

On the transitioning Terraform/OpenTofu-based IaC, I myself will have to wait with experiments until the formae can talk to Azure which is the only cloud provider I currently use. However, I will watch this space :)