Converting Nomad Job Spec HCL to JSON and Back?

It has been very difficult to prop up some basic tooling around HCL based config files.

There are multiple projects that try to help with this issue but I have not been able to find one to do this correctly for my use case. I am hoping somebody might be able to point me in the right direction.

I have tried:

### 1. Using the `nomad` cli.

This would be the ideal way except for a few things.

- It wants to know the values of vars ahead of time so it can interpolate them. I need to keep the variable names and ${} syntax in place.

- There seems to be no way to go back to HCL once we have the JSON

### 2. Using a tool like https://github.com/hashicorp/hcl/tree/main/cmd/hcldec

This would also be ideal, but one big exception:

- It requires the creation of a spec of its own to compile down to the correct 'flavor' of HCL in JSON format. (I think?)
- I could not find any official specs for HashiCorp HCL flavors like Nomad/Terraform and I imagine it would be an effort for me to take on myself. https://hcl.readthedocs.io/en/latest/go_decoding_hcldec.html

### 3. Using third party tools like https://github.com/tmccombs/hcl2json.

This particular ones seems to work well...almost.

- It leaves my variables and their related syntax alone so that is a +1.

- It does not quite generate the right JSON format for Nomad specs. Ex. Constraints, Templates (which are key for me)

- There is no way to go back to HCL after

### 4. Another third party tool - https://github.com/kvz/json2hcl.

- This one can go to from JSON to HCL and reverse.
- Does not support HCL2 (dealbreaker)

After digging into the code a little I found https://github.com/hashicorp/nomad/blob/main/jobspec/parse_job.go but could not find where it runs or how I might be able to use it.

Does anybody have any advice? Or has taken a stab at writing a Nomad `hcldec` spec file? Does `hcldec` do the reverse conversion?

Thanks

Start by reading jobspec/parse_job.go and the linked hcldec and third-party conversion tools. Determine whether HCL2 conversion can preserve variable expressions and Nomad constraints/templates in both directions; done would require a clear supported approach or defined implementation scope.

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