kubelet can not set cluster dns parameter using kube-dns - docker

Question

I have a problem when I set kubelet parameter cluster-dns
My OS is CentOS Linux release 7.0.1406 (Core)
Kernel:Linux master 3.10.0-693.el7.x86_64 #1 SMP Tue Aug 22 21:09:27 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
kubelet config file:
KUBELET_HOSTNAME="--hostname-override=master"
#KUBELET_API_SERVER="--api-servers=http://master:8080
KUBECONFIG="--kubeconfig=/root/.kube/config-demo"
KUBELET_DNS="–-cluster-dns=10.254.0.10"
KUBELET_DOMAIN="--cluster-domain=cluster.local"
# Add your own!
KUBELET_ARGS="--cgroup-driver=systemd --fail-swap-on=false --pod_infra_container_image=177.1.1.35/library/pause:latest"
config file:
KUBE_LOGTOSTDERR="--logtostderr=true"
KUBE_LOG_LEVEL="--v=4"
KUBE_ALLOW_PRIV="--allow-privileged=false"
KUBE_MASTER="--master=http://master:8080"
kubelet.service file:
[Unit]
Description=Kubernetes Kubelet Server
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
After=docker.service
Requires=docker.service
[Service]
WorkingDirectory=/var/lib/kubelet
EnvironmentFile=-/etc/kubernetes/config
EnvironmentFile=-/etc/kubernetes/kubelet
ExecStart=/usr/bin/kubelet \
$KUBE_LOGTOSTDERR \
$KUBE_LOG_LEVEL \
$KUBELET_API_SERVER \
$KUBELET_DNS \
$KUBELET_DOMAIN \
$KUBELET_ADDRESS \
$KUBELET_PORT \
$KUBELET_HOSTNAME \
$KUBE_ALLOW_PRIV \
$KUBELET_ARGS \
$KUBECONFIG
Restart=on-failure
KillMode=process
[Install]
WantedBy=multi-user.target
When I start the kubelet service I can see the "--cluster-dns=10.254.0.10" parameter is correct set:
root 29705 1 1 13:24 ? 00:00:16 /usr/bin/kubelet --logtostderr=true --v=4 –-cluster-dns=10.254.0.10 --cluster-domain=cluster.local --hostname-override=master --allow-privileged=false --cgroup-driver=systemd --fail-swap-on=false --pod_infra_container_image=177.1.1.35/library/pause:latest --kubeconfig=/root/.kube/config-demo
But when I use systemctl status kubelet check the service the cluster-domain parameter just have only on "-" like:
systemctl status kubelet -l
● kubelet.service - Kubernetes Kubelet Server
Loaded: loaded (/usr/lib/systemd/system/kubelet.service; enabled; vendor preset: disabled)
Active: active (running) since Fri 2018-07-13 13:24:07 CST; 5s ago
Docs: https://github.com/GoogleCloudPlatform/kubernetes
Main PID: 29705 (kubelet)
Memory: 30.6M
CGroup: /system.slice/kubelet.service
└─29705 /usr/bin/kubelet --logtostderr=true --v=4 -cluster-dns=10.254.0.10 --cluster-domain=cluster.local --hostname-override=master --allow-privileged=false --cgroup-driver=systemd --fail-swap-on=false --pod_infra_container_image=177.1.1.35/library/pause:latest --kubeconfig=/root/.kube/config-demo
In the logs say there is nothing set in cluster-dns flag:
Jul 13 13:24:07 master kubelet: I0713 13:24:07.680625 29705 flags.go:27] FLAG: --cluster-dns="[]"
Jul 13 13:24:07 master kubelet: I0713 13:24:07.680636 29705 flags.go:27] FLAG: --cluster-domain="cluster.local"
The Pods with errors:
pod: "java-deploy-69c84746b9-b2d7j_default(ce02d183-864f-11e8-9bdb-525400c4f6bf)". kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to "Default" policy.
My kube-dns config file:
apiVersion: v1
kind: Service
metadata:
name: kube-dns
namespace: kube-system
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
kubernetes.io/name: "KubeDNS"
spec:
selector:
k8s-app: kube-dns
clusterIP: 10.254.0.10
ports:
- name: dns
port: 53
protocol: UDP
- name: dns-tcp
port: 53
protocol: TCP
---
#apiVersion: v1
#kind: ServiceAccount
#metadata:
# name: kube-dns
# namespace: kube-system
# labels:
# kubernetes.io/cluster-service: "true"
# addonmanager.kubernetes.io/mode: Reconcile
---
apiVersion: v1
kind: ConfigMap
metadata:
name: kube-dns
namespace: kube-system
labels:
addonmanager.kubernetes.io/mode: EnsureExists
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: kube-dns
namespace: kube-system
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
spec:
# replicas: not specified here:
# 1. In order to make Addon Manager do not reconcile this replicas parameter.
# 2. Default is 1.
# 3. Will be tuned in real time if DNS horizontal auto-scaling is turned on.
strategy:
rollingUpdate:
maxSurge: 10%
maxUnavailable: 0
selector:
matchLabels:
k8s-app: kube-dns
template:
metadata:
labels:
k8s-app: kube-dns
annotations:
scheduler.alpha.kubernetes.io/critical-pod: ''
spec:
tolerations:
- key: "CriticalAddonsOnly"
operator: "Exists"
volumes:
- name: kube-dns-config
configMap:
name: kube-dns
optional: true
containers:
- name: kubedns
image: 177.1.1.35/library/kube-dns:1.14.8
resources:
# TODO: Set memory limits when we've profiled the container for large
# clusters, then set request = limit to keep this container in
# guaranteed class. Currently, this container falls into the
# "burstable" category so the kubelet doesn't backoff from restarting it.
limits:
memory: 170Mi
requests:
cpu: 100m
memory: 70Mi
livenessProbe:
httpGet:
path: /healthcheck/kubedns
port: 10054
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
readinessProbe:
httpGet:
path: /readiness
port: 8081
scheme: HTTP
# we poll on pod startup for the Kubernetes master service and
# only setup the /readiness HTTP server once that's available.
initialDelaySeconds: 3
timeoutSeconds: 5
args:
- --domain=cluster.local.
- --dns-port=10053
- --config-dir=/kube-dns-config
- --kube-master-url=http://177.1.1.40:8080
- --v=2
env:
- name: PROMETHEUS_PORT
value: "10055"
ports:
- containerPort: 10053
name: dns-local
protocol: UDP
- containerPort: 10053
name: dns-tcp-local
protocol: TCP
- containerPort: 10055
name: metrics
protocol: TCP
volumeMounts:
- name: kube-dns-config
mountPath: /kube-dns-config
- name: dnsmasq
image: 177.1.1.35/library/dnsmasq:1.14.8
livenessProbe:
httpGet:
path: /healthcheck/dnsmasq
port: 10054
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
args:
- -v=2
- -logtostderr
- -configDir=/etc/k8s/dns/dnsmasq-nanny
- -restartDnsmasq=true
- --
- -k
- --cache-size=1000
- --no-negcache
- --log-facility=-
- --server=/cluster.local/127.0.0.1#10053
- --server=/in-addr.arpa/127.0.0.1#10053
- --server=/ip6.arpa/127.0.0.1#10053
ports:
- containerPort: 53
name: dns
protocol: UDP
- containerPort: 53
name: dns-tcp
protocol: TCP
# see: https://github.com/kubernetes/kubernetes/issues/29055 for details
resources:
requests:
cpu: 150m
memory: 20Mi
volumeMounts:
- name: kube-dns-config
mountPath: /etc/k8s/dns/dnsmasq-nanny
- name: sidecar
image: 177.1.1.35/library/sidecar:1.14.8
livenessProbe:
httpGet:
path: /metrics
port: 10054
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
args:
- --v=2
- --logtostderr
- --probe=kubedns,127.0.0.1:10053,kubernetes.default.svc.cluster.local,5,SRV
- --probe=dnsmasq,127.0.0.1:53,kubernetes.default.svc.cluster.local,5,SRV
ports:
- containerPort: 10054
name: metrics
protocol: TCP
resources:
requests:
memory: 20Mi
cpu: 10m
dnsPolicy: Default # Don't use cluster DNS.
#serviceAccountName: kube-dns

Answer 1

Recheck your kubelet config:
KUBELET_DNS="–-cluster-dns=10.254.0.10"
It seems to me that the first dash is longer than the second.
Maybe a copy&paste you made causes that strange character.
Retype it and retry.