kubelet 无法使用 kube-dns 设置集群 dns 参数

问题描述 投票：0回答：2

我设置 kubelet 参数时遇到问题 

cluster-dns

我的操作系统是 CentOS Linux 版本 7.0.1406（核心）
内核：

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 配置文件：

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"

配置文件：

KUBE_LOGTOSTDERR="--logtostderr=true"  
KUBE_LOG_LEVEL="--v=4"
KUBE_ALLOW_PRIV="--allow-privileged=false"
KUBE_MASTER="--master=http://master:8080"

kubelet.service 文件：

[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

当我启动 kubelet 服务时，我可以看到“--cluster-dns=10.254.0.10”参数设置正确：

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

但是当我使用 systemctl status kubelet 检查服务时，集群域参数只有“-”，例如：

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

日志中显示 cluster-dns 标志中没有设置任何内容：

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"

有错误的 Pod：

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.

我的 kube-dns 配置文件：

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
docker kubernetes centos7 kube-dns
2个回答
1
投票

重新检查您的 kubelet 配置：

KUBELET_DNS="–-cluster-dns=10.254.0.10"

在我看来，第一个破折号比第二个破折号长。

也许您所做的复制和粘贴导致了奇怪的字符。 重新输入并重试。

0
投票

出现以下错误：

[root@master-node yum.repos.d]# kubeadm init W0427 14：43：28.946949 2265 kubelet.go：200]启动Kubelet时无法自动设置CgroupDriver：无法执行'docker info -f {{.CgroupDriver}}'：退出状态1 I0427 14:43:29.613170 2265 version.go:251] 远程版本更新得多：v1.30.0；回落至： stable-1.20 [init] 使用 Kubernetes 版本：v1.20.15 [飞行前] 运行飞行前检查 [警告 Firewalld]：firewalld 处于活动状态，请确保端口 [6443 10250] 已打开，否则您的集群可能无法正常运行 [警告服务-Docker]：docker服务未启用，请运行“systemctl启用docker.service” [预检] 系统验证失败。打印验证的输出： 内核版本：3.10.0-1160.114.2.el7.x86_64 CONFIG_NAMESPACES：已启用 CONFIG_NET_NS：启用 CONFIG_PID_NS：启用 CONFIG_IPC_NS：启用 CONFIG_UTS_NS：启用 CONFIG_CGROUPS：启用 CONFIG_CGROUP_CPUACCT：启用 CONFIG_CGROUP_DEVICE：启用 CONFIG_CGROUP_FREEZER：启用 CONFIG_CGROUP_SCHED：启用 CONFIG_CPUSETS：启用 CONFIG_MEMCG：启用 CONFIG_INET：启用 CONFIG_EXT4_FS：启用（作为模块） CONFIG_PROC_FS：启用 CONFIG_NETFILTER_XT_TARGET_REDIRECT：启用（作为模块） CONFIG_NETFILTER_XT_MATCH_COMMENT：启用（作为模块） CONFIG_OVERLAY_FS：启用（作为模块） CONFIG_AUFS_FS：未设置 - aufs 必需的。 CONFIG_BLK_DEV_DM：启用（作为模块） 操作系统：Linux CGROUPS_CPU：已启用 CGROUPS_CPUACCT：启用 CGROUPS_CPUSET：启用 CGROUPS_DEVICES：已启用 CGROUPS_FREEZER：启用 CGROUPS_MEMORY：启用 CGROUPS_PIDS：启用 CGROUPS_HUGETLB：已启用 错误执行阶段预检：[预检]发生一些致命错误： [错误 CRI]：容器运行时未运行：输出：无法连接到位于 unix:///var/run/docker.sock 的 Docker 守护进程。 docker 守护进程是否正在运行？ ，错误：退出状态1 [错误服务-Docker]：docker 服务未激活，请运行“systemctl start docker.service” [错误 IsDockerSystemdCheck]：无法执行“docker info -f {{.CgroupDriver}}”：退出状态 1 [错误文件内容--proc-sys-net-bridge-bridge-nf-call-iptables]：/proc/sys/net/bridge/bridge-nf-call-iptables 不存在 [错误 FileContent--proc-sys-net-ipv4-ip_forward]：/proc/sys/net/ipv4/ip_forward 内容未设置为 1 [错误系统验证]：执行“docker info --format '{{json .}}'”失败 输出：无法连接到位于 unix:///var/run/docker.sock 的 Docker 守护进程。 docker 守护进程是否正在运行？ 错误：退出状态 1 [飞行前] 如果您知道自己在做什么，则可以使用 

--ignore-preflight-errors=...
进行非致命检查 要查看此错误的堆栈跟踪，请使用 --v=5 或更高版本执行

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