Expected imageRepository field to be validated

[randomvariable]

What keywords did you search in kubeadm issues before filing this one?

validate
imageRepository

Is this a BUG REPORT or FEATURE REQUEST?

Bug report

Versions

kubeadm version (use kubeadm version): v1.25.0

Environment:

• Kubernetes version (use kubectl version): N/A
• Cloud provider or hardware configuration: N/A
• OS (e.g. from /etc/os-release): N/A
• Kernel (e.g. uname -a): N/A
• Container runtime (CRI) (e.g. containerd, cri-o): N/A
• Container networking plugin (CNI) (e.g. Calico, Cilium): N/A
• Others: N/A

What happened?

I modified a kind kubeadm configuration as follows:

apiServer:
  certSANs:
  - localhost
  - 127.0.0.1
  extraArgs:
    runtime-config: ""
apiVersion: kubeadm.k8s.io/v1beta3
clusterName: kind
controlPlaneEndpoint: kind-control-plane:6443
dns:
  imageRepository: |
    registry.contoso.com/kubernetes
      s

the key bit being

dns:
  imageRepository: |
    registry.contoso.com/kubernetes
      s

This was then passed into kubeadm init --config blah.yaml, and kubeadm proceeded until preflight with

[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
error execution phase preflight: [preflight] Some fatal errors occurred:
        [ERROR ImagePull]: failed to pull image registry.contoso.com/kubernetes
  s
/coredns:v1.9.3: output: E0921 13:07:35.156113    6667 remote_image.go:238] "PullImage from image servic
e failed" err="rpc error: code = Unknown desc = failed to parse image reference \"registry.contoso.com/kubernetes\\n  s\\n/coredns:v1.9.3\": invalid reference format" image=<
        registry.contoso.com/kubernetes
          s
        /coredns:v1.9.3
 >

What you expected to happen?

kubeadm to throw a validation error.

See also kubernetes-sigs/cluster-api#7257

How to reproduce it (as minimally and precisely as possible)?

See above.

Anything else we need to know?

[SataQiu]

Is there a common way/util to verify the imageRepository format for different image runtimes?
This seems to be an implementation based on regular expressions https://github.com/distribution/distribution/blob/main/reference/reference.go#L7

[neolit123]

not sure if a good idea to import the distribution package in kubeadm, might be fine though....can we use the go url stdlib instead? this is mentioned in kubernetes-sigs/cluster-api#7257

[pacoxu]

refer to kubernetes/kubernetes#103849, we plan to migrate to distribution v3, but it is pending due to many new transitive dependencies.

[neolit123]

my vote is to just do some golang stdlib url validation

[SataQiu]

kubelet and kubectl currently uses github.com/docker/distribution/reference to validate image format.
I think kubeadm better keep consistent behavior with kubelet/kubectl.

If k/k migrate to distribution v3, we should also keep up to date.

https://github.com/kubernetes/kubernetes/blob/master/pkg/kubelet/images/image_manager.go#L23

https://github.com/kubernetes/kubernetes/blob/cac53883f4714452f3084a22e4be20d042a9df33/staging/src/k8s.io/kubectl/pkg/cmd/debug/debug.go#L266-L269

[neolit123]

I think kubeadm better keep consistent behavior with kubelet.

ok, +1