fix: print consistent json/yaml output

[devholic]

What

Print consistent output for commands.

Why

Currently, some commands (e.g. k3d cluster list or k3d cluster get) prints differently per output option (json / yaml). This behavior may break interoperability and can make users hard to figure out the difference between outputs.

Changes

Replace gopkg.in/yaml.v2 with sigs.k8s.io/yaml, which converts the json-encoded struct to yaml.

(sigs.k8s.io/yaml is a wrapper for gopkg.in/yaml.v2 - https://github.com/kubernetes-sigs/yaml/blob/b5bdf49df8aeb9756eee686adc7b4a6b3640bc14/yaml.go#L30-L38)

Implications

Commands will print same struct for both json / yaml output options.

This change may breaks previous behavior, since this commit removes yaml tag from structs.

Open Questions

I think it would be better to use either gopkg.in/yaml.v2 or sigs.k8s.io/yaml only across the repository for consistency, and there is an advantage that we don't have to add yaml tags to struct fields. WDYT?

[iwilltry42]

Hi @devholic , thanks for opening this PR! 👍
I agree with your observation and it sounds like a good idea to consistently use sigs.k8s.io/yaml all over the repo.
Would you mind extending your PR to cover this? :)

[devholic]

Sure 🙂

[devholic]

@iwilltry42 I squashed commit, but you can check changelogs at devholic/k3d@main...devholic:k3d:cluster-list-consistent-output-patch 🙂

[iwilltry42]

LGTM

[iwilltry42]

Thank you very much!
While code-wise it looked good to me, it seems to break cluster creation during tests:
ERRO[2022-07-01T11:47:23Z] Failed Cluster Start: error during post-start cluster preparation: error while rewriting /var/lib/rancher/k3s/server/manifests/coredns.yaml in k3d-registrytest-server-0: error splitting yaml: error marshaling into JSON: json: unsupported type: map[interface {}]interface {}

[devholic]

@iwilltry42

Thank you very much!
While code-wise it looked good to me, it seems to break cluster creation during tests:

I found that gopkg.in/yaml.v2 uses map[interface{}]interface{} internally, so it breaks SplitYAML and callers. Here is the patch for this issue (squashed) 🙏

devholic/k3d@b11130a...devholic:k3d:cluster-list-consistent-output-patch

[iwilltry42]

LGTM! Tests passed ✔️

[iwilltry42]

Sorry for the late review! Thanks for this addition :)

[iwilltry42]

@all-contributors please add @devholic for code

[allcontributors]

@iwilltry42

I've put up a pull request to add @devholic! 🎉