* docs: update json jobs docs
Did you know that Nomad has not 1 but 2 JSON formats for jobs? 2½ if you
want to acknowledge that sometimes our JSON job representations have a
Job top-level wrapper and sometimes do not.
The 2½ formats are:
```
1. HCL JSON
2. Input API JSON (top-level Job field)
2.5. Output API JSON (lacks top-level Job field)
```
`#2` is what our docs consider our API JSON. `#2.5` seems to be an
accident of history we can't fix with breaking API compatibility.
`#1` is an even more interesting accident of history: the `jobspec2`
package automatically detects if the input to Parse is JSON and switches
to a JSON parser. This behavior is undocumented, the format is
unspecified, and there is no official HashiCorp tooling to produce this
JSON from HCL. The plot thickens when you discover popular third party
tools like hcl2json.com and https://github.com/tmccombs/hcl2json seem to
produce JSON that `nomad run` accepts!
Since we have no telemetry around whether or not anyone passes HCL JSON
to `nomad run`, and people don't file bugs around features that Just
Work, I'm choosing to leave that code path in place and *acknowledged
but not suggested* in documentation.
See https://github.com/hashicorp/hcl/issues/498 for a more comprehensive
discussion of what officially supporting HCL JSON in Nomad would look
like.
(I also added some of the missing fields to the (Input API flavor) JSON
Job documentation, but it still needs a lot of work to be
comprehensive.)
Co-authored-by: Tim Gross <tgross@hashicorp.com>
Custom variable validation is a useful feature that is supported by
Nomad and not just Terraform. As such it should be documented on the
input variable page.
I've cribbed the content from the terraform docs so this should be
consistent across projects
HCL2 locals don't have type constraints, and the map syntax is interpreted as
an object. So users may need to explictly convert to map for some functions.
The `convert` function documentation was missing the required type constructor
parameter for collections.
Block labels are not expressions so they can't be interpolated without hacks
like `dynamic` blocks. Clarify this so that we don't confuse users who
shouldn't need to dig into the subtle nuances between expressions and blocks.
