starlark-go VS ytt

Starlark in go https://github.com/google/starlark-go is a great way to combine the best of both, the ease of use of Python and the simplicity of go.

I have been building a platform for deploying internal web applications using this approach https://github.com/claceio/clace. Use Starlark to configure the application, the platform itself is built in go.

The big unknown is your task definition: what does user-defined logic look like? If you're expecting go code, that's gonna need some cleverness because of the compiled nature of it. There's a node runtime implemented in go if you want to provide sandboxed javascript (check the source of k6.io, it's the main one I know that uses it). If you want to provide building blocks and let them compose them, starlark might be a good choice.

Another one of those (with broader language support) is the Starlark language, which has a Go implementation: https://github.com/google/starlark-go

Every config format gets as complex to be touring complete in the end. We had similar problems and eventually got rid of that complexity and switched to starlark (the bazel config language), was a huge benefit for the tools. https://github.com/google/starlark-go "Starlark is a dialect of Python intended for use as a configuration language. Like Python, it is an untyped dynamic language with high-level data types, first-class functions with lexical scope, and garbage collection."

Direct link to the Go implementation of Starlark: https://github.com/google/starlark-go

For a Python-like syntax, https://github.com/google/starlark-go is the language used in Babel. It's very mature, but since it is used in a massive mature project with a specific purpose, it doesn't move fast or drift from the spec of its Java-based sibling. It doesn't have exception try except blocks or some other features you might expect, but for short extension logic, it might be exactly what you want with the stability you can depend upon.

Context: https://github.com/google/starlark-go/blob/cfacd890221418a2dc2c736f7b5e3476c38709b1/starlark/int_posix64.go

Thus envd is more like Dockerfile, while it uses a simplified python dialect starlark https://github.com/google/starlark-go as the build language.

Use Go (mostly for starlark-go)

YTT - YTT is a templating tool that understands YAML structure. It helps you easily configure complex software via reusable templates and user provided values using the Starlark language.

Adding https://carvel.dev/ytt/ to the list. I was happy using this tool as IMO it mixes good things from Helm and Kustomize, however the syntax is ugly and repelling my colleagues to have a closer look.

> Templating yaml is a terrible, terrible idea

I've had a good time using ytt: https://carvel.dev/ytt/. It implements language-aware templating, which is IMO the only reasonable way to do it.

`ytt` is part of the Carvel toolchain. https://carvel.dev/ytt/

I agree with you on `you will want to see just plain texts instead of a bunch of templating token with hidden logic.` Which is why I think https://carvel.dev/ytt/ would be great. We could generate these templates in pipelines, or we could just make it easier to maintain what we have.

For more advanced configuration management you might be interested in ytt ( https://carvel.dev/ytt/ ) which is a "yaml-aware" templating tool. it lets you do "patches" via an overlay mechanism to add or remove specific yaml blocks, and it also lets you use a simplified python dialect for more complicated logic. With ytt you would put your DNS IP into a "data values" file and then run ytt to render it into the configs before handing them off to the deployment tool. e.g. `ytt -f | kubectl apply`

I said this above as well: ytt (https://carvel.dev/ytt/) lets you embed starlark into valid yaml, among other cute tricks for managing biz-logic in configs.

Manifests are generated with ytt (https://carvel.dev/ytt/).

This is why you should consider https://carvel.dev/ytt/