Docker image name over 3 layers caused kubenab replace instead of add private registry

Describe the bug When docker image name over 3 layers, it caused kubenab replace instead of add private registry to pod（flag REPLACE_REGISTRY_URL=false）.

Attach relevant code：if (len(imageParts) < 3) || repRegUrl（Not quite reasonable here）

func handleContainer(container *v1.Container, dockerRegistryUrl string) bool {
    log.Println("Container Image is", container.Image)

    if !containsRegisty(whitelistedRegistries, container.Image) {
        message := fmt.Sprintf("Image is not being pulled from Private Registry: %s", container.Image)
        log.Printf(message)

        imageParts := strings.Split(container.Image, "/")
        newImage := ""

        // pre-pend new Docker Registry Domain
        repRegUrl, _ := strconv.ParseBool(replaceRegistryUrl) // we do not need to check for errors here, since we have done this already in checkArguments()
        if (len(imageParts) < 3) || repRegUrl {
            newImage = dockerRegistryUrl + "/" + container.Image
        } else {
            imageParts[0] = dockerRegistryUrl
            newImage = strings.Join(imageParts, "/")
        }
        log.Printf("Changing image registry to: %s", newImage)

        container.Image = newImage
        return true
    } else {
        log.Printf("Image is being pulled from Private Registry: %s", container.Image)
    }
    return false
}

To Reproduce Steps to reproduce the behavior:

Install kubenab with those Settings: https://github.com/jfrog/kubenab/tree/master/deployment

apiVersion: apps/v1
kind: Deployment
metadata:
name: kubenab
namespace: kube-system
labels:
app: kubenab
spec:
replicas: 3
selector:
matchLabels:
  app: kubenab
template:
metadata:
  labels:
    app: kubenab
spec:
  priorityClassName: system-cluster-critical
  nodeSelector:
    role: master
  affinity:
    podAntiAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
          - key: app
            operator: In
            values:
            - kubenab
        topologyKey: kubernetes.io/hostname
  containers:
  - name: kubenab
    image: kubenab:0.3.2
    imagePullPolicy: IfNotPresent
    env:
      - name: DOCKER_REGISTRY_URL
        value: "100.2.0.115:8088"
      - name: REGISTRY_SECRET_NAME
        value: 'regsecret'
      - name: WHITELIST_NAMESPACES
        value: "kube-system,default"
      - name: WHITELIST_REGISTRIES
        value: "100.2.0.115:8088"
      - name: REPLACE_REGISTRY_URL
        value: "false"
    ports:
      - containerPort: 443
        name: https
    volumeMounts:
    - name: tls
      mountPath: /etc/admission-controller/tls
    resources: {}
  volumes:
    - name: tls
      secret:
        secretName: kubenab-certs

Create a new Pod with image name over 3 layers

kind: Deployment
apiVersion: apps/v1
metadata:
name: nfs-client-provisioner
namespace: repo
spec:
replicas: 1
strategy:
type: Recreate
selector:
matchLabels:
  app: nfs-client-provisioner
template:
metadata:
  labels:
    app: nfs-client-provisioner
spec:
  nodeSelector:
    role: master
  serviceAccountName: nfs-client-provisioner
  containers:
    - name: nfs-client-provisioner
      image: repo/external_storage/nfs-client-provisioner:v3.1.0
      imagePullPolicy: Always
      volumeMounts:
        - name: nfs-client-root
          mountPath: /persistentvolumes
      env:
        - name: PROVISIONER_NAME
          value: fuseim.pri/ifs
        - name: NFS_SERVER
          value: 100.2.0.5
        - name: NFS_PATH
          value: /opt/share/test
  volumes:
    - name: nfs-client-root
      nfs:
        server: 100.2.0.5
        path: /opt/share/test

Check status with kubectl describe [POD]

Events:
Type     Reason          Age                  From               Message
----     ------          ----                 ----               -------
Normal   Scheduled       119s                 default-scheduler  Successfully assigned repo/nfs-client-provisioner-65cff57884-d7dlq to node3
Normal   SandboxChanged  104s (x2 over 111s)  kubelet, node3     Pod sandbox changed, it will be killed and re-created.
Warning  Failed          45s (x5 over 105s)   kubelet, node3     Error: ImagePullBackOff
Normal   Pulling         33s (x4 over 112s)   kubelet, node3     Pulling image "100.2.0.115:8088/external_storage/nfs-client-provisioner:v3.1.0"
Warning  Failed          33s (x4 over 112s)   kubelet, node3     Failed to pull image "100.2.0.115:8088/external_storage/nfs-client-provisioner:v3.1.0": rpc error: code = Unknown desc = Error response from daemon: pull access denied for 100.2.0.115:8088/external_storage/nfs-client-provisioner, repository does not exist or may require 'docker login'
Warning  Failed          33s (x4 over 112s)   kubelet, node3     Error: ErrImagePull
Normal   BackOff         20s (x6 over 105s)   kubelet, node3     Back-off pulling image "100.2.0.115:8088/external_storage/nfs-client-provisioner:v3.1.0"

Expected behavior kubenab add private registry to pod.

Should be 100.2.0.115:8088/repo/external_storage/nfs-client-provisioner:v3.1.0

Logs

kubectl logs -f -n kube-system kubenab-5ccbd84cdb-lsbdx

2019/10/15 01:04:14 AdmissionReview Namespace is: repo
2019/10/15 01:04:14 Container Image is repo/external_storage/nfs-client-provisioner:v3.1.0
2019/10/15 01:04:14 Image is not being pulled from Private Registry: repo/external_storage/nfs-client-provisioner:v3.1.0
2019/10/15 01:04:14 Changing image registry to: 100.2.0.115:8088/external_storage/nfs-client-provisioner:v3.1.0
2019/10/15 01:04:14 Serving request: /validate
2019/10/15 01:04:14 {"kind":"AdmissionReview","apiVersion":"admission.k8s.io/v1beta1","request":{"uid":"ae07f519-604e-4a51-879c-58d684eae321","kind":{"group":"","version":"v1","kind":"Pod"},"resource":{"group":"","version":"v1","resource":"pods"},"requestKind":{"group":"","version":"v1","kind":"Pod"},"requestResource":{"group":"","version":"v1","resource":"pods"},"namespace":"repo","operation":"CREATE","userInfo":{"username":"system:serviceaccount:kube-system:replicaset-controller","uid":"b7c19393-6ec2-47a2-8855-d511bfcdede0","groups":["system:serviceaccounts","system:serviceaccounts:kube-system","system:authenticated"]},"object":{"kind":"Pod","apiVersion":"v1","metadata":{"name":"nfs-client-provisioner-65cff57884-d7dlq","generateName":"nfs-client-provisioner-65cff57884-","namespace":"repo","uid":"046c4978-cc0c-4214-b714-e30f2bbc011f","creationTimestamp":"2019-10-15T01:04:14Z","labels":{"app":"nfs-client-provisioner","pod-template-hash":"65cff57884"},"ownerReferences":[{"apiVersion":"apps/v1","kind":"ReplicaSet","name":"nfs-client-provisioner-65cff57884","uid":"577716ce-c3a1-48d0-8246-006da6b68acf","controller":true,"blockOwnerDeletion":true}]},"spec":{"volumes":[{"name":"nfs-client-root","nfs":{"server":"100.2.0.5","path":"/opt/share/test"}},{"name":"nfs-client-provisioner-token-2sgsx","secret":{"secretName":"nfs-client-provisioner-token-2sgsx","defaultMode":420}}],"containers":[{"name":"nfs-client-provisioner","image":"100.2.0.115:8088/external_storage/nfs-client-provisioner:v3.1.0","env":[{"name":"PROVISIONER_NAME","value":"fuseim.pri/ifs"},{"name":"NFS_SERVER","value":"100.2.0.5"},{"name":"NFS_PATH","value":"/opt/share/test"}],"resources":{},"volumeMounts":[{"name":"nfs-client-root","mountPath":"/persistentvolumes"},{"name":"nfs-client-provisioner-token-2sgsx","readOnly":true,"mountPath":"/var/run/secrets/kubernetes.io/serviceaccount"}],"terminationMessagePath":"/dev/termination-log","terminationMessagePolicy":"File","imagePullPolicy":"Always"}],"restartPolicy":"Always","terminationGracePeriodSeconds":30,"dnsPolicy":"ClusterFirst","nodeSelector":{"role":"master"},"serviceAccountName":"nfs-client-provisioner","serviceAccount":"nfs-client-provisioner","securityContext":{},"imagePullSecrets":[{"name":"regsecret"}],"schedulerName":"default-scheduler","tolerations":[{"key":"node.kubernetes.io/not-ready","operator":"Exists","effect":"NoExecute","tolerationSeconds":300},{"key":"node.kubernetes.io/unreachable","operator":"Exists","effect":"NoExecute","tolerationSeconds":300}],"priority":0,"enableServiceLinks":true},"status":{"phase":"Pending","qosClass":"BestEffort"}},"oldObject":null,"dryRun":false,"options":{"kind":"CreateOptions","apiVersion":"meta.k8s.io/v1"}}}

Additional context None

Versions

Kubernetes Cluster Version: v1.15.2
kubenab Version: 0.3.2

jfrog / kubenab

Docker image name over 3 layers caused kubenab replace instead of add private registry #27

Versions