Lua support is NOT being added for templating. It's being added to enable extensions in charts (a new thing) and for cross platform plugins. Existing style plugins will still work. This is providing some extras to help enable more cross platform work.
There are a couple reasons Lua was chosen and documentation has been written up as well.
1. There are go packages for this so we can do it in a cross platform manner (mac/win/linux/bsd/etc). Helm is used on many platforms. 2. Security issues, especially with extensions to charts, have a path forward to address. In a similar way to how we opt-in for apps to use features on cell phones we can do that for features used in extensions.
The people who did the analysis has embedded JS engines in applications recently. They are aware of the benefits, pitfalls, and how it all works.
Why are you suggesting jsonnet then?
Not exactly. Two things to know...
First, a little history.
Only a tiny amount of people have asked for it. A prototype was created and no one, not even the ksonnet devs, were up for taking the work forward from the prototype phase. The code is still up on GitHub and Helm was built with the intent of more engines being used.
Second, ksonnet is going through some major changes right now. We can all come back and look on it again when it's ready.
Helm 3 is working to make it easier to bring your own tools, like jsonnet. It's just not likely to be baked in or replace YAML. People really aren't asking for it much.
