graduate the flag for structural output --experimental-output to just --output

[neolit123]

noticed the flag is still experimental here:
kubernetes/website#45911

the feature of structural output in kubeadm has been active for a 5+ releases.
this implies the backend works. the API is still alpha, but it's not attached to the backend usage.
we can just graduate the output API in another iteration.

https://github.com/carlory/kubernetes/blob/227c2e7c2b2c05a9c8b2885460e28e4da25cf558/cmd/kubeadm/app/util/output/output.go#L102-L108

in 1.31:

• mark --experimental-output as deprecated. add a new flag --output that also does the same thing
  TODO

in 1.32:

• remove --experimental-output
  TODO

[neolit123]

@carlory please say if you don't have the time to work on this.

[carlory]

@neolit123 I can do it 😊

[carlory]

but according to the KEP, some commands still need to be implemented. https://github.com/kubernetes/enhancements/tree/master/keps/sig-cluster-lifecycle/kubeadm/2504-kubeadm-machine-output#goals

[neolit123]

but according to the KEP, some commands still need to be implemented. https://github.com/kubernetes/enhancements/tree/master/keps/sig-cluster-lifecycle/kubeadm/2504-kubeadm-machine-output#goals

the KEP is out of date (i think0, but new commands can be added and still use --output.
we can prefix the description of --output for a particular command as EXPERIMENTAL

generally using --experimental-.... is a breaking change and not desired.

[sftim]

add a new flag --output that also does the same thing

Could we do that part in a v1.30 patch release? Any reason why we couldn't?

[neolit123]

add a new flag --output that also does the same thing

Could we do that part in a v1.30 patch release? Any reason why we couldn't?

not a bugfix, thus can't be advocated for.