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DNS Addon Kubernetes CentOS 7群集

2016-07-26 147 views
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我一直在努力让DNS插件在CentOS 7.2群集上工作。我使用这里的方向安装了集群：http://severalnines.com/blog/installing-kubernetes-cluster-minions-centos7-manage-pods-servicesDNS Addon Kubernetes CentOS 7群集

在这个配置中，master正在运行：etcd，kube-scheduler，kube-apiserver和kube-controller-manager。节点正在运行：docker，kubelet和kube-proxy以及flanneld。在这种配置下群集工作正常。豆荚，服务都在工作。下一步是尝试启用DNS。

注意：此群集未使用证书进行身份验证。

对于如何做到这一点，有几个“指南”，但它们似乎都不适用于这种类型的集群。

首先你能帮我解决一些困惑。 dns addon容器在哪里运行？

  • 他们必须在主人身上运行吗？
  • 它们可以像群集上的其他任何群集一样部署吗？

这里是我到目前为止已经试过：

Kubernetes版本：香草从安装yum。

# kubectl version 
Client Version: version.Info{Major:"1", Minor:"2", GitVersion:"v1.2.0" GitCommit:"a4463d9a1accc9c61ae90ce5d314e248f16b9f05", GitTreeState:"clean"}  
Server Version: version.Info{Major:"1", Minor:"2", GitVersion:"v1.2.0", GitCommit:"a4463d9a1accc9c61ae90ce5d314e248f16b9f05", GitTreeState:"clean"}

在下面我已经更换了模板变量与1个副本集的天空dns.yaml文件，设定dns_domain为“cluster.local”。根据StackOverflow上的一些建议，我在“/ kube-dns”容器“--kube-master-url = http://10.2.1.245:8080”中增加了一个命令行。

SkyDNS-rc.yaml（指向KUBE-DNS的V18）

apiVersion: v1 
kind: ReplicationController 
metadata: 
    name: kube-dns-v18 
    namespace: kube-system 
    labels: 
    k8s-app: kube-dns 
    version: v18 
    kubernetes.io/cluster-service: "true" 
spec: 
    replicas: 1 
    selector: 
    k8s-app: kube-dns 
    version: v18 
    template: 
    metadata: 
     labels: 
     k8s-app: kube-dns 
     version: v18 
     kubernetes.io/cluster-service: "true" 
    spec: 
     containers: 
     - name: kubedns 
     image: gcr.io/google_containers/kubedns-amd64:1.6 
     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: 
      cpu: 100m 
      memory: 200Mi 
      requests: 
      cpu: 100m 
      memory: 100Mi 
     livenessProbe: 
      httpGet: 
      path: /healthz 
      port: 8080 
      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: 30 
      timeoutSeconds: 5 
     args: 
     # command = "/kube-dns" 
     - --domain=cluster.local 
     - --dns-port=10053 
     - --kube-master-url=http://10.2.1.245:8080 
     ports: 
     - containerPort: 10053 
      name: dns-local 
      protocol: UDP 
     - containerPort: 10053 
      name: dns-tcp-local 
      protocol: TCP 
     - name: dnsmasq 
     image: gcr.io/google_containers/kube-dnsmasq-amd64:1.3 
     args: 
     - --cache-size=1000 
     - --no-resolv 
     - --server=127.0.0.1#10053 
     ports: 
     - containerPort: 53 
      name: dns 
      protocol: UDP 
     - containerPort: 53 
      name: dns-tcp 
      protocol: TCP 
     - name: healthz 
     image: gcr.io/google_containers/exechealthz-amd64:1.0 
     resources: 
      # keep request = limit to keep this container in guaranteed class 
      limits: 
      cpu: 10m 
      memory: 20Mi 
      requests: 
      cpu: 10m 
      memory: 20Mi 
     args: 
     - -cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1 >/dev/null && nslookup kubernetes.default.svc.cluster.local 127.0.0.1:10053 >/dev/null 
     - -port=8080 
     - -quiet 
     ports: 
     - containerPort: 8080 
      protocol: TCP 
     dnsPolicy: Default # Don't use cluster DNS.

在每个我已经更新了的/ etc/kubernetes/CONF文件中添加DSN的节点（主站和3个爪牙）的最后一节（完整文件发布完整文件）。

如果我使用上面的复制控制器，是否需要添加这些？

的/ etc/kubernetes/conf目录

# logging to stderr means we get it in the systemd journal 
KUBE_LOGTOSTDERR="--logtostderr=true" 

# journal message level, 0 is debug 
KUBE_LOG_LEVEL="--v=0" 

# Should this cluster be allowed to run privileged docker containers 
KUBE_ALLOW_PRIV="--allow-privileged=false" 

# How the controller-manager, scheduler, and proxy find the apiserver 
KUBE_MASTER="--master=http://127.0.0.1:8080" 

# DNS Add-on 
ENABLE_CLUSTER_DNS="${KUBE_ENABLE_CLUSTER_DNS:-true}" 
DNS_SERVER_IP="10.254.100.1" 
DNS_DOMAIN="cluster.local" 
DNS_REPLICAS=1

下面是部署KubeDNS时，我所看到的。

[[email protected] dcook]# kubectl create -f kube-fun/skydns-rc.yaml 
replicationcontroller "kube-dns-v18" created 

[[email protected] dcook]# kubectl get rc kube-dns-v18 --namespace kube-system 
NAME   DESIRED CURRENT AGE 
kube-dns-v18 1   1   34s 

[[email protected] dcook]# kubectl get pods --namespace kube-system 
NAME     READY  STATUS    RESTARTS AGE 
kube-dns-v18-cx4ir 3/3  Running   0   46s

日志：

[[email protected] dcook]# kubectl logs --namespace="kube-system" kube-dns-v18-cx4ir kubedns 
I0726 20:17:52.675064  1 server.go:91] Using http://10.2.1.245:8080 for kubernetes master 
I0726 20:17:52.676138  1 server.go:92] Using kubernetes API v1 
I0726 20:17:52.676498  1 server.go:132] Starting SkyDNS server. Listening on port:10053 
I0726 20:17:52.676815  1 server.go:139] skydns: metrics enabled on :/metrics 
I0726 20:17:52.676836  1 dns.go:166] Waiting for service: default/kubernetes 
I0726 20:17:52.677584  1 logs.go:41] skydns: ready for queries on cluster.local. for tcp://0.0.0.0:10053 [rcache 0] 
I0726 20:17:52.677604  1 logs.go:41] skydns: ready for queries on cluster.local. for udp://0.0.0.0:10053 [rcache 0] 
I0726 20:17:52.867455  1 server.go:101] Setting up Healthz Handler(/readiness, /cache) on port :8081 
I0726 20:17:52.867843  1 dns.go:660] DNS Record:&{10.254.0.1 0 10 10 false 30 0 }, hash:63b49cf0 
I0726 20:17:52.867898  1 dns.go:660] DNS Record:&{kubernetes.default.svc.cluster.local. 443 10 10 false 30 0 }, hash:c3f6ae26 
I0726 20:17:52.868048  1 dns.go:660] DNS Record:&{kubernetes.default.svc.cluster.local. 0 10 10 false 30 0 }, hash:b9b7d845 
I0726 20:17:52.868103  1 dns.go:660] DNS Record:&{10.254.91.7 0 10 10 false 30 0 }, hash:9b59fd9c 
I0726 20:17:52.868137  1 dns.go:660] DNS Record:&{my-nginx.default.svc.cluster.local. 0 10 10 false 30 0 }, hash:b0f41a92 

[[email protected] dcook]# kubectl logs --namespace="kube-system" kube-dns-v18-cx4ir healthz 
2016/07/26 20:17:11 Healthz probe error: Result of last exec: nslookup: can't resolve 'kubernetes.default.svc.cluster.local' 
, at 2016-07-26 20:17:10.667247682 +0000 UTC, error exit status 1 
2016/07/26 20:17:21 Healthz probe error: Result of last exec: nslookup: can't resolve 'kubernetes.default.svc.cluster.local' 
, at 2016-07-26 20:17:20.667213321 +0000 UTC, error exit status 1 
2016/07/26 20:17:31 Healthz probe error: Result of last exec: nslookup: can't resolve 'kubernetes.default.svc.cluster.local' 
, at 2016-07-26 20:17:30.667225804 +0000 UTC, error exit status 1 
2016/07/26 20:17:41 Healthz probe error: Result of last exec: nslookup: can't resolve 'kubernetes.default.svc.cluster.local' 
, at 2016-07-26 20:17:40.667218056 +0000 UTC, error exit status 1 
2016/07/26 20:17:51 Healthz probe error: Result of last exec: nslookup: can't resolve 'kubernetes.default.svc.cluster.local' 
, at 2016-07-26 20:17:50.667724036 +0000 UTC, error exit status 1

来源

2016-07-26 onedsc

回答

1

你缺少一个公开的POD（S）服务：https://github.com/kubernetes/kubernetes/blob/master/cluster/addons/dns/skydns-svc.yaml.in

有你设置的ClusterIP，你再需要的时候你开始使用kubelets。

您需要与--cluster_dns=<the IP you used in the service> --cluster_domain=cluster.local

也开始kubelets，我会更新你的rc YAML到最新版本（V19）模拟你在这里看到的： https://github.com/kubernetes/kubernetes/blob/master/cluster/addons/dns/skydns-rc.yaml.in

来源

2016-08-02 09:20:22 puja

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