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安装 kubedns 插件
官方的yaml文件目录：
kubernetes/cluster/addons/dns。该插件直接使用kubernetes部署，官方的配置文件中包含以下镜像：
gcr.io/google_containers/k8s-dns-dnsmasq-nanny-amd64:1.14.1
gcr.io/google_containers/k8s-dns-kube-dns-amd64:1.14.1
gcr.io/google_containers/k8s-dns-sidecar-amd64:1.14.1
我clone了上述镜像，上传到我的私有镜像仓库：
harbor-001.jimmysong.io/library/k8s-dns-dnsmasq-nanny-amd64:1.14.1
harbor-001.jimmysong.io/library/k8s-dns-kube-dns-amd64:1.14.1
harbor-001.jimmysong.io/library/k8s-dns-sidecar-amd64:1.14.1
以下yaml配置文件中使用的是私有镜像仓库中的镜像。
kubedns-cm.yaml
kubedns-sa.yaml
kubedns-controller.yaml
kubedns-svc.yaml
预定义的 RoleBinding
system:kube-dns 将 kube-system 命名空 间的 kube-dns ServiceAccount 与 system:kube-dns Role 绑定， 该 Role 具有访问 kube-apiserver DNS 相关 API 的权限；$ kubectl get clusterrolebindings system:kube-dns -o yaml
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
annotations:
rbac.authorization.kubernetes.io/autoupdate: "true"
creationTimestamp: 2017-04-11T11:20:42Z
labels:
kubernetes.io/bootstrapping: rbac-defaults
name: system:kube-dns
resourceVersion: "58"
selfLink: /apis/rbac.authorization.k8s.io/v1beta1/clusterrolebindingssystem%3Akube-dns
uid: e61f4d92-1ea8-11e7-8cd7-f4e9d49f8ed0
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: system:kube-dns
subjects:
- kind: ServiceAccount
name: kube-dns
namespace: kube-system
kubedns-controller.yaml 中定义的 Pods 时使用了 kubedns-sa.yaml 文件定义的 kube-dns ServiceAccount，所以具有访问 kube-apiserver DNS 相关 API 的权限。无需修改。
$ diff kubedns-svc.yaml.base kubedns-svc.yaml
30c30
< clusterIP: __PILLAR__DNS__SERVER__
---
> clusterIP: 10.254.0.2
- spec.clusterIP = 10.254.0.2，即明确指定了 kube-dns Service IP，这个 IP 需要和 kubelet 的
--cluster-dns参数值一致；
$ diff kubedns-controller.yaml.base kubedns-controller.yaml
58c58
< image: gcr.io/google_containers/k8s-dns-kube-dns-amd64:1.14.1
---
> image: harbor-001.jimmysong.io/library/k8s-dns-kube-dns-amd64:v1.14.1
88c88
< - --domain=__PILLAR__DNS__DOMAIN__.
---
> - --domain=cluster.local.
92c92
< __PILLAR__FEDERATIONS__DOMAIN__MAP__
---
> #__PILLAR__FEDERATIONS__DOMAIN__MAP__
110c110
< image: gcr.io/google_containers/k8s-dns-dnsmasq-nanny-amd64:1.14.1
---
> image: harbor-001.jimmysong.io/library/k8s-dns-dnsmasq-nanny-amd64:v1.14.1
129c129
< - --server=/__PILLAR__DNS__DOMAIN__/127.0.0.1#10053
---
> - --server=/cluster.local./127.0.0.1#10053
148c148
< image: gcr.io/google_containers/k8s-dns-sidecar-amd64:1.14.1
---
> image: harbor-001.jimmysong.io/library/k8s-dns-sidecar-amd64:v1.14.1
161,162c161,162
< - --probe=kubedns,127.0.0.1:10053,kubernetes.default.svc.__PILLAR__DNS__DOMAIN__,5,A
< - --probe=dnsmasq,127.0.0.1:53,kubernetes.default.svc.__PILLAR__DNS__DOMAIN__,5,A
---
> - --probe=kubedns,127.0.0.1:10053,kubernetes.default.svc.cluster.local.,5,A
> - --probe=dnsmasq,127.0.0.1:53,kubernetes.default.svc.cluster.local.,5,A
- 使用系统已经做了 RoleBinding 的
kube-dnsServiceAccount，该账户具有访问 kube-apiserver DNS 相关 API 的权限；
$ pwd
/root/kubedns
$ ls *.yaml
kubedns-cm.yaml kubedns-controller.yaml kubedns-sa.yaml kubedns-svc.yaml
$ kubectl create -f .
新建一个 Deployment
$ cat >> my-nginx.yaml << EOF
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: my-nginx
spec:
replicas: 2
template:
metadata:
labels:
run: my-nginx
spec:
containers:
- name: my-nginx
image: harbor-001.jimmysong.io/library/nginx:1.9
ports:
- containerPort: 80
EOF
$ kubectl create -f my-nginx.yaml
Export 该 Deployment, 生成
my-nginx 服务$ kubectl expose deploy my-nginx
$ kubectl get services --all-namespaces |grep my-nginx
default my-nginx 10.254.179.239 <none> 80/TCP 42m
创建另一个 Pod，查看
/etc/resolv.conf 是否包含 kubelet 配置的 --cluster-dns 和 --cluster-domain，是否能够将服务 my-nginx 解析到 Cluster IP 10.254.179.239。$ kubectl create -f nginx-pod.yaml
$ kubectl exec nginx -i -t -- /bin/bash
root@nginx:/# cat /etc/resolv.conf
nameserver 10.254.0.2
search default.svc.cluster.local. svc.cluster.local. cluster.local. jimmysong.io
options ndots:5
root@nginx:/# ping my-nginx
PING my-nginx.default.svc.cluster.local (10.254.179.239): 56 data bytes
76 bytes from 119.147.223.109: Destination Net Unreachable
^C--- my-nginx.default.svc.cluster.local ping statistics ---
root@nginx:/# ping kubernetes
PING kubernetes.default.svc.cluster.local (10.254.0.1): 56 data bytes
^C--- kubernetes.default.svc.cluster.local ping statistics ---
11 packets transmitted, 0 packets received, 100% packet loss
root@nginx:/# ping kube-dns.kube-system.svc.cluster.local
PING kube-dns.kube-system.svc.cluster.local (10.254.0.2): 56 data bytes
^C--- kube-dns.kube-system.svc.cluster.local ping statistics ---
6 packets transmitted, 0 packets received, 100% packet loss
从结果来看，service名称可以正常解析。
注意：直接ping ClusterIP是ping不通的，ClusterIP是根据IPtables路由到服务的endpoint上，只有结合ClusterIP加端口才能访问到对应的服务。
最近更新 1yr ago