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所以我有一个运行在 3 个运行 HypriotOS 的树莓派上的 3 节点 kubernetes 集群。自从启动和加入节点以来，我没有做任何事情，除了安装 weave。但是，当我输入时kubectl cluster-info，我会看到两个选项，

Kubernetes master is running at https://192.168.0.35:6443
KubeDNS is running at https://192.168.0.35:6443/api/v1/namespaces/kube-system/services/kube-dns/proxy

当我卷曲第二个网址时，我得到以下响应：

{
  "kind": "Status",
  "apiVersion": "v1",
  "metadata": {},
  "status": "Failure",
  "message": "no endpoints available for service \"kube-dns\"",
  "reason": "ServiceUnavailable",
  "code": 503
}

这是有关我的集群状态的更多信息。

$ kubectl version
Client Version: version.Info{Major:"1", Minor:"7", GitVersion:"v1.7.4", GitCommit:"793658f2d7ca7f064d2bdf606519f9fe1229c381", GitTreeState:"clean", BuildDate:"2017-08-17T08:48:23Z", GoVersion:"go1.8.3", Compiler:"gc", Platform:"linux/arm"}
Server Version: version.Info{Major:"1", Minor:"7", GitVersion:"v1.7.4", GitCommit:"793658f2d7ca7f064d2bdf606519f9fe1229c381", GitTreeState:"clean", BuildDate:"2017-08-17T08:30:51Z", GoVersion:"go1.8.3", Compiler:"gc", Platform:"linux/arm"}




$ kubectl get pods --all-namespaces
NAMESPACE     NAME                                    READY     STATUS             RESTARTS   AGE
kube-system   etcd-node01                             1/1       Running            0          13d
kube-system   kube-apiserver-node01                   1/1       Running            21         13d
kube-system   kube-controller-manager-node01          1/1       Running            5          13d
kube-system   kube-dns-2459497834-v1g4n               3/3       Running            43         13d
kube-system   kube-proxy-1hplm                        1/1       Running            0          5h
kube-system   kube-proxy-6bzvr                        1/1       Running            0          13d
kube-system   kube-proxy-cmp3q                        1/1       Running            0          6d
kube-system   kube-scheduler-node01                   1/1       Running            8          13d
kube-system   weave-net-5cq9c                         2/2       Running            0          6d
kube-system   weave-net-ff5sz                         2/2       Running            4          13d
kube-system   weave-net-z3nq3                         2/2       Running            0          5h


$ kubectl get svc --all-namespaces
NAMESPACE     NAME                   CLUSTER-IP       EXTERNAL-IP   PORT(S)         AGE
default       kubernetes             10.96.0.1        <none>        443/TCP         13d
kube-system   kube-dns               10.96.0.10       <none>        53/UDP,53/TCP   13d


$ kubectl --namespace kube-system describe pod kube-dns-2459497834-v1g4n
Name:           kube-dns-2459497834-v1g4n
Namespace:      kube-system
Node:           node01/192.168.0.35
Start Time:     Wed, 23 Aug 2017 20:34:56 +0000
Labels:         k8s-app=kube-dns
                pod-template-hash=2459497834
Annotations:    kubernetes.io/created-by={"kind":"SerializedReference","apiVersion":"v1","reference":{"kind":"ReplicaSet","namespace":"kube-system","name":"kube-dns-2459497834","uid":"37640de4-8841-11e7-ad32-b827eb0a...
                scheduler.alpha.kubernetes.io/critical-pod=
Status:         Running
IP:             10.32.0.2
Created By:     ReplicaSet/kube-dns-2459497834
Controlled By:  ReplicaSet/kube-dns-2459497834
Containers:
  kubedns:
    Container ID:       docker://9a781f1fea4c947a9115c551e65c232d5fe0aa2045e27e79eae4b057b68e4914
    Image:              gcr.io/google_containers/k8s-dns-kube-dns-arm:1.14.4
    Image ID:           docker-pullable://gcr.io/google_containers/k8s-dns-kube-dns-arm@sha256:ac677e54bef9717220a0ba2275ba706111755b2906de689d71ac44bfe425946d
    Ports:              10053/UDP, 10053/TCP, 10055/TCP
    Args:
      --domain=cluster.local.
      --dns-port=10053
      --config-dir=/kube-dns-config
      --v=2
    State:              Running
      Started:          Tue, 29 Aug 2017 19:09:10 +0000
    Last State:         Terminated
      Reason:           Error
      Exit Code:        137
      Started:          Tue, 29 Aug 2017 17:07:49 +0000
      Finished:         Tue, 29 Aug 2017 19:09:08 +0000
    Ready:              True
    Restart Count:      18
    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-rf19g (ro)
  dnsmasq:
    Container ID:       docker://f8e17df36310bc3423a74e3f6989204abac9e83d4a8366561e54259418030a50
    Image:              gcr.io/google_containers/k8s-dns-dnsmasq-nanny-arm:1.14.4
    Image ID:           docker-pullable://gcr.io/google_containers/k8s-dns-dnsmasq-nanny-arm@sha256:a7469e91b4b20f31036448a61c52e208833c7cb283faeb4ea51b9fa22e18eb69
    Ports:              53/UDP, 53/TCP
    Args:
      -v=2
      -logtostderr
      -configDir=/etc/k8s/dns/dnsmasq-nanny
      -restartDnsmasq=true
      --
      -k
      --cache-size=1000
      --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
    State:              Running
      Started:          Tue, 29 Aug 2017 19:09:52 +0000
    Last State:         Terminated
      Reason:           Error
      Exit Code:        137


$ kubectl --namespace kube-system describe svc kube-dns
Name:           kube-dns
Namespace:      kube-system
Labels:         k8s-app=kube-dns
            kubernetes.io/cluster-service=true
            kubernetes.io/name=KubeDNS
Annotations:        <none>
Selector:       k8s-app=kube-dns
Type:           ClusterIP
IP:         10.96.0.10
Port:           dns 53/UDP
Endpoints:      10.32.0.2:53
Port:           dns-tcp 53/TCP
Endpoints:      10.32.0.2:53
Session Affinity:   None
Events:         <none>

我无法弄清楚这里发生了什么，因为除了按照此处的说明进行操作外，我什么也没做。这个问题在多个版本的 kubernetes 以及多个网络覆盖（包括 flannel）之间一直存在。所以它开始让我认为这是 rpi 本身的一些问题。

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1 回答 1

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更新：以下假设不是此错误消息的完整解释。代理 API声明：

创建连接代理

将 GET 请求连接到 Pod 的代理

获取 /api/v1/namespaces/{namespace}/pods/{name}/proxy

现在的问题是究竟是什么connect GET requests to proxy of Pod意思，但我坚信这意味着将 GET 请求转发到 pod。这意味着下面的假设是正确的。

我检查了其他不是为 HTTP 流量设计的服务，它们都产生了这个错误消息，而为 HTTP 流量设计的服务运行良好（例如，/api/v1/namespaces/kube-system/services/kubernetes-dashboard/proxy）。

我相信这是正常行为 - 没什么好担心的。如果您查看kube-dns集群内的服务对象，您会发现它仅向端口 53（标准 DNS 端口）提供内部端点 - 所以我假设该kube-dns服务仅对正确的 DNS 查询做出良好响应。使用 curl 您试图在此服务上发出正常的 GET 请求，这应该会导致错误响应。

从您给定的集群信息来看，您的所有 pod 看起来都不错，我敢打赌您的服务端点也已正确公开。您可以检查 via kubectl get ep kube-dns --namespace=kube-systemwhich 应该产生类似的东西：

$ kubectl get ep kube-dns --namespace=kube-system
NAME       ENDPOINTS                                                         AGE
kube-dns   100.101.26.65:53,100.96.150.198:53,100.101.26.65:53 + 1 more...   20d

在我的集群 (k8s 1.7.3) 上， curl GET/api/v1/namespaces/kube-system/services/kube-dns/proxy也会导致您提到的错误消息，但我从来没有遇到过 DNS 问题，所以我希望我对此的假设是正确的。

于 2017-09-07T15:57:57.060 回答