Consistent YAML formatting

[frankfarzan]

kpt needs to consistently format resources. Previously, there was kpt cfg fmt which is now removed in favor of having a global flag that controls styling/formatting as a cross-cutting feature.

As part of this, all examples in /package-examples (highest priority) and test data should be pre-formatted (Unless testing formatting logic itself). For example, eval comand on the nginx package in the Quickstart produces formatting changes which creates unnecessary noise:

https://kpt.dev/book/01-getting-started/02-quickstart

What's worse, there's no way to automatically preformat the example. We should also reconsider removing fmt command.

[frankfarzan]

cc @phanimarupaka @droot @mortent

[droot]

I think having a dedicated command to format resources sounds useful to me. Which subcommand group we should bring it in ?

[frankfarzan]

kpt pkg format is consistent with kpt pkg view (fka tree), etc. In english: "I want to format my package".

[phanimarupaka]

How about having it as a format function instead ? By default any such functionality should be a function unless there is a great need to include it as part of cli. kpt pkg tree/kpt pkg view/kpt pkg desc qualifies to be a cli command as will be frequently used and is the first thing a consumer would do.

[phanimarupaka]

GoogleContainerTools/kpt-functions-catalog#242

[mengqiy]

It seems we start to format the resources in kpt fn render (#1813).
@phanimarupaka Is there a reason not doing it for kpt fn eval?

[phanimarupaka]

Yes. eval can be invoked on validator functions as well. Mutating resources in such scenarios looks awkward. If users want to format resources, they can invoke explicit format image.

[mengqiy]

Thanks for clarification!