Service “kube-dns” is invalid: spec.clusterIP: Invalid value: “10.10.0.10”: field is immutable

问题

I setup my cluster by kubeadm. At the last step i exec kubeadm init --config kubeadm.conf --v=5. I get the error about the clusterIp value. Here is the part of the output:

    I0220 00:16:27.625920   31630 clusterinfo.go:79] creating the RBAC rules for exposing the cluster-info ConfigMap in the kube-public namespace
I0220 00:16:27.947941   31630 kubeletfinalize.go:88] [kubelet-finalize] Assuming that kubelet client certificate rotation is enabled: found "/var/lib/kubelet/pki/kubelet-client-current.pem"
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
I0220 00:16:27.949398   31630 kubeletfinalize.go:132] [kubelet-finalize] Restarting the kubelet to enable client certificate rotation
[addons]: Migrating CoreDNS Corefile
I0220 00:16:28.447420   31630 dns.go:381] the CoreDNS configuration has been migrated and applied: .:53 {
    errors
    health {
       lameduck 5s
    }
    ready
    kubernetes cluster.local in-addr.arpa ip6.arpa {
       pods insecure
       fallthrough in-addr.arpa ip6.arpa
       ttl 30
    }
    prometheus :9153
    forward . /etc/resolv.conf
    cache 30
    loop
    reload
    loadbalance
}
.
I0220 00:16:28.447465   31630 dns.go:382] the old migration has been saved in the CoreDNS ConfigMap under the name [Corefile-backup]
I0220 00:16:28.447486   31630 dns.go:383] The changes in the new CoreDNS Configuration are as follows:
Service "kube-dns" is invalid: spec.clusterIP: Invalid value: "10.10.0.10": field is immutable
unable to create/update the DNS service
k8s.io/kubernetes/cmd/kubeadm/app/phases/addons/dns.createDNSService
    /workspace/anago-v1.17.0-rc.2.10+70132b0f130acc/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/cmd/kubeadm/app/phases/addons/dns/dns.go:323
k8s.io/kubernetes/cmd/kubeadm/app/phases/addons/dns.createCoreDNSAddon
    /workspace/anago-v1.17.0-rc.2.10+70132b0f130acc/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/cmd/kubeadm/app/phases/addons/dns/dns.go:305
k8s.io/kubernetes/cmd/kubeadm/app/phases/addons/dns.coreDNSAddon

And my config file like this:

apiVersion: kubeadm.k8s.io/v1beta2
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 172.16.5.151
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: master02
#  taints:
#  - effect: NoSchedule
#    key: node-role.kubernetes.io/master
---
apiServer:
  certSANs:
    - "172.16.5.150"
    - "172.16.5.151"
    - "172.16.5.152"
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns:
  type: CoreDNS
etcd:
  external:
    endpoints:
    - "https://172.16.5.150:2379"
    - "https://172.16.5.151:2379"
    - "https://172.16.5.152:2379"
    caFile: /etc/k8s/pki/ca.pem
    certFile: /etc/k8s/pki/etcd.pem
    keyFile: /etc/k8s/pki/etcd.key

imageRepository: registry.aliyuncs.com/google_containers
kind: ClusterConfiguration
kubernetesVersion: v1.17.0
networking:
  dnsDomain: cluster.local
  serviceSubnet: 10.10.0.0/16
  podSubnet: 192.168.0.0/16
scheduler: {}

I checked the kube-apiserver.yaml generated by kubeadm. the --service-cluster-ip-range=10.10.0.0/16 settings is contains 10.10.0.10 you can see below:

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    component: kube-apiserver
    tier: control-plane
  name: kube-apiserver
  namespace: kube-system
spec:
  containers:
  - command:
    - kube-apiserver
    - --advertise-address=172.16.5.151
    - --allow-privileged=true
    - --authorization-mode=Node,RBAC
    - --client-ca-file=/etc/kubernetes/pki/ca.crt
    - --enable-admission-plugins=NodeRestriction
    - --enable-bootstrap-token-auth=true
    - --etcd-cafile=/etc/k8s/pki/ca.pem
    - --etcd-certfile=/etc/k8s/pki/etcd.pem
    - --etcd-keyfile=/etc/k8s/pki/etcd.key
    - --etcd-servers=https://172.16.5.150:2379,https://172.16.5.151:2379,https://172.16.5.152:2379
    - --insecure-port=0
    - --kubelet-client-certificate=/etc/kubernetes/pki/apiserver-kubelet-client.crt
    - --kubelet-client-key=/etc/kubernetes/pki/apiserver-kubelet-client.key
    - --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname
    - --proxy-client-cert-file=/etc/kubernetes/pki/front-proxy-client.crt
    - --proxy-client-key-file=/etc/kubernetes/pki/front-proxy-client.key
    - --requestheader-allowed-names=front-proxy-client
    - --requestheader-client-ca-file=/etc/kubernetes/pki/front-proxy-ca.crt
    - --requestheader-extra-headers-prefix=X-Remote-Extra-
    - --requestheader-group-headers=X-Remote-Group
    - --requestheader-username-headers=X-Remote-User
    - --secure-port=6443
    - --service-account-key-file=/etc/kubernetes/pki/sa.pub
    - --service-cluster-ip-range=10.10.0.0/16
    - --tls-cert-file=/etc/kubernetes/pki/apiserver.crt
    - --tls-private-key-file=/etc/kubernetes/pki/apiserver.key
    image: registry.aliyuncs.com/google_containers/kube-apiserver:v1.17.0
    imagePullPolicy: IfNotPresent
    livenessProbe:
      failureThreshold: 8
      httpGet:
        host: 172.16.5.151
        path: /healthz
        port: 6443
        scheme: HTTPS
      initialDelaySeconds: 15
      timeoutSeconds: 15
    name: kube-apiserver
    resources:
      requests:
        cpu: 250m
    volumeMounts:
    - mountPath: /etc/ssl/certs
      name: ca-certs
      readOnly: true
    - mountPath: /etc/pki
      name: etc-pki
      readOnly: true
    - mountPath: /etc/k8s/pki
      name: etcd-certs-0
      readOnly: true
    - mountPath: /etc/kubernetes/pki
      name: k8s-certs
      readOnly: true
  hostNetwork: true
  priorityClassName: system-cluster-critical
  volumes:
  - hostPath:
      path: /etc/ssl/certs
      type: DirectoryOrCreate
    name: ca-certs
  - hostPath:
      path: /etc/pki
      type: DirectoryOrCreate
    name: etc-pki
  - hostPath:
      path: /etc/k8s/pki
      type: DirectoryOrCreate
    name: etcd-certs-0
  - hostPath:
      path: /etc/kubernetes/pki
      type: DirectoryOrCreate
    name: k8s-certs
status: {}

As you see above. all the service-ip-range has been set to 10.10.0.0/16. It is strange that when i exec "kubectl get svc" I get the kubernetes clusterip is 10.96.0.1

[root@master02 manifests]# kubectl get svc
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   2d3h

which means the default service-ip-range is: 10.96.0.0/16. And what i modifyed does not work. Does anyone know How to Custom the service-ip-range scope. And how to slove my problem?

回答1:

Posting this answer as community wiki to expand and explain root cause.

When kubeadm is initiated, and we do not specify any flags, $ kubeadm init it will create kubeadm cluster with default values. You can check in Kubernetes docs flags which can be specified during initilization and which are default values.

--service-cidr string Default: "10.96.0.0/12" Use alternative range of IP address for service VIPs.

That's the reason why default kubernetes service used 10.96.0.1 as ClusterIP.

Here OP also wanted to use own config.

--config string Path to a kubeadm configuration file.

Whole initialization workflow can be found here.

As Kubernetes docs exmplain Kubeadm reset

Performs a best effort revert of changes made by kubeadm init or kubeadm join.

Depends on our configuration sometimes, some configs stay on the cluster.

Issue, that OP encountered was mentioned here - External etcd clean up

kubeadm reset will not delete any etcd data if external etcd is used. This means that if you run kubeadm init again using the same etcd endpoints, you will see state from previous clusters.

Regarding Immutable fields: Service “kube-dns” is invalid: spec.clusterIP: Invalid value: “10.10.0.10”: field is immutable. In Kubernetes, some fields are secured to prevent changes that might disrupt working of the cluster.

If any field is immutable but we have to change it, this object must be removed and add again.

回答2:

Because this node I joined the cluster as a node beforeBecause this node I joined the cluster as a node before.Later I reset this with "kubeadm reset " command.After the reset, I joined it as a master role to the cluster. So I get the error in my question above. The error is because the range of the clusterip before I reset is already recorded in the etcd cluster. And "kubeadm reset" command does not clean up the data in the etcd.So the new definition of clusterip conflicts with the original.So the solution is to clean up the data in the etcd and reset it again. (Since the cluster I built is a test cluster, I cleaned the etcd directly. Please be careful in the production environment)

来源：https://stackoverflow.com/questions/60305724/service-kube-dns-is-invalid-spec-clusterip-invalid-value-10-10-0-10-fiel