mirror of https://github.com/easzlab/kubeasz.git
70 lines
2.0 KiB
Markdown
70 lines
2.0 KiB
Markdown
## 部署集群 DNS
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DNS 是 k8s 集群首先需要部署的，集群中的其他 pods 使用它提供域名解析服务；主要可以解析 `集群服务名 SVC` 和 `Pod hostname`；目前 k8s v1.9+ 版本可以有两个选择：`kube-dns` 和 `coredns`，可以选择其中一个部署安装。
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### 部署 dns
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配置文件参考 `https://github.com/kubernetes/kubernetes` 项目目录 `kubernetes/cluster/addons/dns`
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+ 安装
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``` bash
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# 安装 kube-dns
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$ kubectl create -f /etc/ansible/manifests/kubedns
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# 或者选择安装 coredns
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$ kubectl create -f /etc/ansible/manifests/coredns
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```
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+ 集群 pod默认继承 node的dns 解析，修改 kubelet服务启动参数 --resolv-conf=""，可以更改这个特性，详见 kubelet 启动参数
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### 验证 dns服务
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新建一个测试nginx服务
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`kubectl run nginx --image=nginx --expose --port=80`
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确认nginx服务
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``` bash
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kubectl get pod|grep nginx
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nginx-7cbc4b4d9c-fl46v 1/1 Running 0 1m
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kubectl get svc|grep nginx
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nginx ClusterIP 10.68.33.167 <none> 80/TCP 1m
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```
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测试pod busybox
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``` bash
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kubectl run busybox --rm -it --image=busybox /bin/sh
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If you don't see a command prompt, try pressing enter.
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/ # cat /etc/resolv.conf
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nameserver 10.68.0.2
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search default.svc.cluster.local. svc.cluster.local. cluster.local.
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options ndots:5
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# 测试集群内部服务解析
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/ # nslookup nginx
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Server: 10.68.0.2
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Address 1: 10.68.0.2 kube-dns.kube-system.svc.cluster.local
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Name: nginx
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Address 1: 10.68.33.167 nginx.default.svc.cluster.local
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/ # nslookup kubernetes
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Server: 10.68.0.2
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Address 1: 10.68.0.2 kube-dns.kube-system.svc.cluster.local
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Name: kubernetes
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Address 1: 10.68.0.1 kubernetes.default.svc.cluster.local
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# 测试外部域名的解析，默认集成node的dns解析
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/ # nslookup www.baidu.com
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Server: 10.68.0.2
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Address 1: 10.68.0.2 kube-dns.kube-system.svc.cluster.local
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Name: www.baidu.com
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Address 1: 180.97.33.108
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Address 2: 180.97.33.107
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/ #
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```
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