Helm from Jsonnet

This repository is a proof of concept for building simplified Helm charts from Jsonnet libraries. It only supports string variables.

values.yaml

The values.yaml file is constructed using the top level _config hidden object that is common to most Kubernetes Jsonnet libraries such as cortex-jsonnet.

A dummy _config object is used in the Tanka/Jsonnet evaluation process to put the appropriate Go template strings in place for Helm templating. For more detail see the environments/cortex/main.jsonnet file.

See the Makefile to view the targets involved. To reconstruct all the files and view the resulting helm chart

$ make -B
$ helm template helm/cortex --generate-name

The dummy helm config is constructed using the template function in lib/helm.libsonnet;

Helm uses Go templates which can cause issues when Jsonnet libraries have Go templates themselves like in the prometheus-ksonnet library. This is an issue with helm (helm/helm#2798). To work around this, an escape function has been written that has Helm render raw strings. For an example, see the environments/prometheus-ksonnet/main.jsonnet file.

Dependencies

For nixos:

$ nix-shell

or if you have Lorri and direnv:

$ direnv allow

Otherwise, you need tanka, jsonnet-bundler, helm, and jsonnet