Content of registries.yaml is not correct

[bk201]

rancherd version: v0.0.1-alpha13

To Reproduce

Init a cluster with the following config:

# cat /etc/rancher/rancherd/config.yaml
role: cluster-init
token: somethingrandom
kubernetesVersion: v1.21.8+k3s1
rancherVersion: stable

registries:
  mirrors:
    docker.io:
      endpoint:
        - "http://192.168.2.106:5000"
    k8s.gcr.io:
      endpoint:
        - "http://192.168.2.106:5001"
    quay.io:
      endpoint:
        - "http://192.168.2.106:5002"

The generated registries.yaml file has content:

# cat /etc/rancher/k3s/registries.yaml
Auths: null
Configs: null
Mirrors:
  docker.io:
    Endpoints: null
    Rewrites: null
  k8s.gcr.io:
    Endpoints: null
    Rewrites: null
  quay.io:
    Endpoints: null
    Rewrites: null

If I changed the field endpoint to endpoints in the /etc/rancher/rancherd/config.yaml file, the generated file will be:

# cat /etc/rancher/k3s/registries.yaml
Auths: null
Configs: null
Mirrors:
  docker.io:
    Endpoints:
    - http://192.168.2.106:5000
    Rewrites: null
  k8s.gcr.io:
    Endpoints:
    - http://192.168.2.106:5001
    Rewrites: null
  quay.io:
    Endpoints:
    - http://192.168.2.106:5002
    Rewrites: null

This seems to be correct but k3s only accepts the key endpoint, not endpoints
https://rancher.com/docs/k3s/latest/en/installation/private-registry/#mirrors

Some investigation

The Endpoints field has no json field tag: https://github.com/rancher/wharfie/blob/efd07c927031e0b324f5ce56211eea0c4a13ca06/pkg/registries/types.go#L9

And package "sigs.k8s.io/yaml" is used to marshal the registry, which uses json.marshal and converts the result to yaml

rancherd/pkg/registry/registry.go

Line 18 in 7e9f0fe

data, err := yaml.Marshal(registry)

This might be the reason the generated file has key endpoint"s".