jsonnet

https://jsonnet.org/

A configuration language for app and tool developers

• Generate config data
• Side-effect free
• Organize, simplify, unify
• Manage sprawling config

A simple extension of JSON

• Open source (Apache 2.0)
• Familiar syntax
• Reformatter, linter
• Editor & IDE integrations
• Formally specified

here's a good article arguing for its usage, "Why are we templating YAML?"

firstly, let's define some jsonnet:

{
  image: std.extVar('image'),
}

Then, we can generate it using the Jsonnet command line tool, passing in the external variable as we need to:

jsonnet image.jsonnet -V image="my-image"
{
   "image": "my-image"
}

I might try this out as a command-line template language