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Comment by morelisp | Hacker News Reader

It's absolutely crazy to me how many tools are in common use for k8s templating which would all be wiped away with any decent macro system.

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I can't actually put it into production at my company, but for selfish catharsis, I ran datamodel-codegen over our cluster's jsonschema and generated Python pydantic models for all resources. I was able to rewrite all our helm using pure Python and Pydantic models, since Pydantic serializes to json and json is valid yaml. Felt pretty good

We don't have any CRD, but the approach would extend to those, plus you get auto complete. The k8s jsonachema isn't super easy to work directly with, though.

The template engine is not specific to Kubernetes but Golang. I wish they used something more adapted. https://pkg.go.dev/text/template

Not just helm. There are probably a half dozen tools for rendering manifests in our company, only some use text/template, and they all suck. Text replacements are bad. Declarative structured patches are bad. Control flow in JSON is bad. We've had a language for dealing with generating complex nested structured data for years!

Have you seen Jsonnet, Dhall, and Cue? They are configuration language that are more limited than general purpose languages, more powerful that static, and designed for config files unlike templates.

text/template is probably ok... For some version of text. ditto with jinja and most templating languages. The cardinal sin of DevOps is using text macros to produce structured data. It only exists because unfortunately there is no other lowest common denominator for every config file syntax.

Sure and that forgives its use in maybe, like, Salt and Ansible. Not in Kubernetes where everything is structured in the same way, even with API-available schemas, to begin with.

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