Kube-dns 始终处于挂起状态

Question

我已经在 virt-manager 虚拟机上部署了 kubernetes link

https://kubernetes.io/docs/setup/independent/install-kubeadm/

当我将另一个虚拟机加入集群时，我发现 kube-dns 处于挂起状态。

root@ubuntu1:~# kubectl get pods --all-namespaces 
NAMESPACE     NAME                              READY     STATUS    RESTARTS   AGE
kube-system   etcd-ubuntu1                      1/1       Running   0          7m
kube-system   kube-apiserver-ubuntu1            1/1       Running   0          8m
kube-system   kube-controller-manager-ubuntu1   1/1       Running   0          8m
kube-system   kube-dns-86f4d74b45-br6ck         0/3       Pending   0          8m
kube-system   kube-proxy-sh9lg                  1/1       Running   0          8m
kube-system   kube-proxy-zwdt5                  1/1       Running   0          7m
kube-system   kube-scheduler-ubuntu1            1/1       Running   0          8m


root@ubuntu1:~# kubectl --namespace=kube-system describe pod kube-dns-86f4d74b45-br6ck
Name:           kube-dns-86f4d74b45-br6ck
Namespace:      kube-system
Node:           <none>
Labels:         k8s-app=kube-dns
                pod-template-hash=4290830601
Annotations:    <none>
Status:         Pending
IP:             
Controlled By:  ReplicaSet/kube-dns-86f4d74b45
Containers:
  kubedns:
    Image:       k8s.gcr.io/k8s-dns-kube-dns-amd64:1.14.8
    Ports:       10053/UDP, 10053/TCP, 10055/TCP
    Host Ports:  0/UDP, 0/TCP, 0/TCP
    Args:
      --domain=cluster.local.
      --dns-port=10053
      --config-dir=/kube-dns-config
      --v=2
    Limits:
      memory:  170Mi
    Requests:
      cpu:      100m
      memory:   70Mi
    Liveness:   http-get http://:10054/healthcheck/kubedns delay=60s timeout=5s period=10s #success=1 #failure=5
    Readiness:  http-get http://:8081/readiness delay=3s timeout=5s period=10s #success=1 #failure=3
    Environment:
      PROMETHEUS_PORT:  10055
    Mounts:
      /kube-dns-config from kube-dns-config (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from kube-dns-token-4fjt4 (ro)
  dnsmasq:
    Image:       k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64:1.14.8
    Ports:       53/UDP, 53/TCP
    Host Ports:  0/UDP, 0/TCP
    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
    Requests:
      cpu:        150m
      memory:     20Mi
    Liveness:     http-get http://:10054/healthcheck/dnsmasq delay=60s timeout=5s period=10s #success=1 #failure=5
    Environment:  <none>
    Mounts:
      /etc/k8s/dns/dnsmasq-nanny from kube-dns-config (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from kube-dns-token-4fjt4 (ro)
  sidecar:
    Image:      k8s.gcr.io/k8s-dns-sidecar-amd64:1.14.8
    Port:       10054/TCP
    Host Port:  0/TCP
    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
    Requests:
      cpu:        10m
      memory:     20Mi
    Liveness:     http-get http://:10054/metrics delay=60s timeout=5s period=10s #success=1 #failure=5
    Environment:  <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-dns-token-4fjt4 (ro)
Conditions:
  Type           Status
  PodScheduled   False 
Volumes:
  kube-dns-config:
    Type:      ConfigMap (a volume populated by a ConfigMap)
    Name:      kube-dns
    Optional:  true
  kube-dns-token-4fjt4:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  kube-dns-token-4fjt4
    Optional:    false
QoS Class:       Burstable
Node-Selectors:  <none>
Tolerations:     CriticalAddonsOnly
                 node-role.kubernetes.io/master:NoSchedule
                 node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type     Reason            Age               From               Message
  ----     ------            ----              ----               -------
  Warning  FailedScheduling  6m (x7 over 7m)   default-scheduler  0/1 nodes are available: 1 node(s) were not ready.
  Warning  FailedScheduling  3s (x19 over 6m)  default-scheduler  0/2 nodes are available: 2 node(s) were not ready.

任何人都可以帮助我如何解构它并找到实际问题吗？

任何帮助都会有很大用处

提前致谢。

Answer 1

首先，如果您运行 kubectl get nodes 这是否显示 both/all 个节点处于就绪状态？

如果是，我遇到了这个问题并发现在检查 kubectl get events 时显示 pods 失败，因为它们至少需要 2 个 CPU 才能运行。

因为我最初是运行通过 VirtualBox 在旧的 Macbook Pro 上安装它，所以我不得不放弃并使用 AWS（当然可以使用其他云平台）以便每个节点获得多个 CPU。

Answer 2

除了@justcompile 所写的内容之外，您至少需要 2 CPU 个核心 才能运行所有 pods来自 kube-system 命名空间没有问题。

您需要验证您在那个盒子上有多少资源，并将其与 Pods 中每个人所做的 CPU 保留进行比较。

例如，在您提供的输出中，我可以看到您的 DNS 服务试图为 CPU 核心的 10% 保留：

Requests:
  cpu:      100m

您可以使用以下方式检查每个已部署的 pods 及其 CPU 预留：

kubectl describe pods --namespace=kube-system

Answer 3

在你的原因中 kubectl get pods --all-namespaces 输出看不到任何关于 pods 网络的信息。

所以你可以选择一个网络实现并且必须在 kube-dns 完全部署之前安装一个 Pod 网络。详情 kube-dns is stuck in the Pending state and install pod network solution

Kube-dns 始终处于挂起状态

Kube-dns always in pending state

kubernetes

kube-dns