Extend 'config print' command with additional options

[xmudrii]

What this PR does / why we need it:

This is an experimental approach to the config print command. I tested and confirmed it works well. The config print command is now extended to support most of the options, so someone can build a configuration file without browsing GitHub and searching for the config.yaml.dist manifest.

The idea behind this is to improve the user experience, so the user can work with our API without having to browse GitHub to find config.yaml.dist or to browse the API types. Various tools have different approaches to this, so I can believe we can find a good one too.

However, I have several concerns regarding this topic:

• All those flags can potentially confuse the user. It might make more sense to leave hosts and enableOpenIDConnect (so we have all features supported) and drop others as they're mostly like not-commonly used.
  • Instead of all flags we can put the most common ones and have a set flag that changes some property not covered by flags. That way the command is not overloaded with flags, but it's still possible to build usable configuration file.
  • Negative side of the set flag is that you still have to know the API.
• Instead of a single config print command we can split them to two commands:
  • A config create command that works like one in this PR
  • A config print command that has two "modes":
    • Print full config.yaml.dist
    • Print just example manifest like we already have without this PR
    • In this case printing full config.yaml.dist might overlap with config create, so potentially we can drop one.
• Another problem is maintainability—we need to make sure that we incorporate every API change here.
  • Using yamled is nice as we get a nice looking manifest without all the empty fields, but there is no strongly enforced type safety.
  • Using kyaml.UnmarshalStrict ensures that it'll not print invalid manifest, but in that case, there should be some unit test cases in the CI to check is it working.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
xref #254

Release note:

Extend 'config print' command with additional options

/assign @kron4eg

[kron4eg]

@xmudrii I just noticed that provider is not getting validated

$ kubeone config print -p unknown_provider
apiVersion: kubeone.io/v1alpha1
kind: KubeOneCluster
versions:
  kubernetes: 1.14.1
cloudProvider:
  name: unknown_provider

[kron4eg]

small tweaks are needed

[kron4eg]

/lgtm
/approve

[kubermatic-bot]

LGTM label has been added.

Git tree hash: 01ecf6cbdfffbd2269b5ce6f2f736a27dded1f5a

[kubermatic-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kron4eg

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[xmudrii]

/override pull-kubeone-e2e-aws-conformance-1.13.5
/override pull-kubeone-e2e-digitalocean-conformance-1.13.5
/override pull-kubeone-e2e-digitalocean-conformance-1.14.1
/override pull-kubeone-e2e-digitalocean-upgrade-1.13.5-1.14.1

[kubermatic-bot]

@xmudrii: Overrode contexts on behalf of xmudrii: pull-kubeone-e2e-aws-conformance-1.13.5, pull-kubeone-e2e-digitalocean-conformance-1.13.5, pull-kubeone-e2e-digitalocean-conformance-1.14.1, pull-kubeone-e2e-digitalocean-upgrade-1.13.5-1.14.1

In response to this:

/override pull-kubeone-e2e-aws-conformance-1.13.5
/override pull-kubeone-e2e-digitalocean-conformance-1.13.5
/override pull-kubeone-e2e-digitalocean-conformance-1.14.1
/override pull-kubeone-e2e-digitalocean-upgrade-1.13.5-1.14.1

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[xmudrii]

/test pull-kubeone-dependencies

[kubermatic-bot]

@xmudrii: The following tests failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-kubeone-e2e-digitalocean-conformance-1.14.1	cec0888	link	/test pull-kubeone-e2e-digitalocean-conformance-1.14.1
pull-kubeone-e2e-digitalocean-conformance-1.13.5	cec0888	link	/test pull-kubeone-e2e-digitalocean-conformance-1.13.5
pull-kubeone-e2e-digitalocean-upgrade-1.13.5-1.14.1	cec0888	link	/test pull-kubeone-e2e-digitalocean-upgrade-1.13.5-1.14.1
pull-kubeone-e2e-aws-conformance-1.13.5	cec0888	link	/test pull-kubeone-e2e-aws-conformance-1.13.5
pull-kubeone-e2e-aws-conformance-1.14.1	cec0888	link	/test pull-kubeone-e2e-aws-conformance-1.14.1

Full PR test history

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[xmudrii]

/override pull-kubeone-e2e-aws-conformance-1.14.1

[kubermatic-bot]

@xmudrii: Overrode contexts on behalf of xmudrii: pull-kubeone-e2e-aws-conformance-1.14.1

In response to this:

/override pull-kubeone-e2e-aws-conformance-1.14.1

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.