146 lines
4.7 KiB
Markdown
146 lines
4.7 KiB
Markdown
---
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vssueId: 158
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layout: LearningLayout
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description: Kubernetes中_网络策略定义了一组Pod是否允许相互通信_或者与网络中的其他端点endpoint通信_本文描述了几个在K8S集群的名称空间中创建NetworkPolicy的例子
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meta:
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- name: keywords
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content: Kubernetes教程,K8S教程,Kubernetes Network Policies, K8S 网络策略
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---
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# Network Policies - Example
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<AdSenseTitle>
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> 参考文档： [Declare Network Policy](https://kubernetes.io/docs/tasks/administer-cluster/declare-network-policy/)
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本文描述了如何在 Kubernetes 集群中通过创建 NetworkPolicy 的方式来声明网络策略，以管理 Pod 之间的网络通信流量。
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[[TOC]]
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</AdSenseTitle>
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## 前提条件
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您已经安装了 Kubernetes 集群，如果没有，请参考文档 [离线安装高可用的Kubernetes集群](/install/install-k8s.html)
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您可以使用 kubectl 访问您的集群，请参考文档 [安装Kubectl](/install/install-kubectl.html)
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请确保您使用的网络插件支持 Network Policy，如下的网络插件都是可以的：
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* [Calico](https://kubernetes.io/docs/tasks/administer-cluster/network-policy-provider/calico-network-policy/) 如果您按照 [离线安装高可用的Kubernetes集群](/install/install-k8s.html) 安装的集群，默认是 calico 网络插件
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* [Cilium](https://kubernetes.io/docs/tasks/administer-cluster/network-policy-provider/cilium-network-policy/)
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* [Kube-router](https://kubernetes.io/docs/tasks/administer-cluster/network-policy-provider/kube-router-network-policy/)
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* [Romana](https://kubernetes.io/docs/tasks/administer-cluster/network-policy-provider/romana-network-policy/)
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* [Weave Net](https://kubernetes.io/docs/tasks/administer-cluster/network-policy-provider/weave-network-policy/)
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::: tip 排序
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按字母顺序排序，不代表推荐顺序。本文中的例子对上述所有网络插件都有效
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:::
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## 创建一个Deployment并配置Service
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* 创建一个 `nginx` Deployment 用于演示 Kubernetes 的 NetworkPolicy：
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``` sh
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kubectl create deployment nginx --image=nginx
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```
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输出结果
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```
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deployment.apps/nginx created
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```
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* 通过Service暴露该Deployment
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``` sh
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kubectl expose deployment nginx --port=80
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```
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输出结果
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```
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service/nginx exposed
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```
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* 查询结果
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``` sh
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kubectl get svc,pod
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```
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输出结果
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```
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NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
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service/kubernetes 10.100.0.1 <none> 443/TCP 46m
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service/nginx 10.100.0.16 <none> 80/TCP 33s
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NAME READY STATUS RESTARTS AGE
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pod/nginx-701339712-e0qfq 1/1 Running 0 35s
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```
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## 从另外一个pod访问Service
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默认是可以从另外一个Pod访问 `nginx` Service 的。下面的方法可以执行此测试：
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在 `default` 名称空间中创建 busybox 容器，并执行 `wget` 命令：
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``` sh
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kubectl run --generator=run-pod/v1 busybox --rm -ti --image=busybox -- /bin/sh
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```
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请按照下面的例子，在命令行中执行 `wget --spider --timeout=1 nginx`
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```
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Waiting for pod default/busybox-472357175-y0m47 to be running, status is Pending, pod ready: false
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Hit enter for command prompt
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/ # wget --spider --timeout=1 nginx
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Connecting to nginx (10.100.0.16:80)
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/ #
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```
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## 限制对nginx的访问
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下面的 `NetworkPolicy` 可以声明：只有带 `access=true` 标签的 Pod 可以访问 `nginx` 服务：
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<<< @/.vuepress/public/statics/learning/svc/network-policy.yaml
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* 执行命令以创建该 NetworkPolicy：
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``` sh
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kubectl apply -f https://kuboard.cn/statics/learning/svc/network-policy.yaml
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```
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输出结果如下：
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```
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networkpolicy.networking.k8s.io/access-nginx created
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```
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## 从不带标签的Pod访问nginx服务
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如果从不带标签的 Pod 访问该 nginx 服务，请求将超时：
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``` sh
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kubectl run --generator=run-pod/v1 busybox --rm -ti --image=busybox -- /bin/sh
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```
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请按照下面的例子在命令行中执行 `wget --spider --timeout=1 nginx`
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```
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Waiting for pod default/busybox-472357175-y0m47 to be running, status is Pending, pod ready: false
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Hit enter for command prompt
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/ # wget --spider --timeout=1 nginx
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Connecting to nginx (10.100.0.16:80)
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wget: download timed out
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/ #
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```
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## 从带有标签的Pod访问nginx服务
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从带有 `access=true` 标签的 Pod 中访问 nginx 服务，将能够执行成功：
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``` sh
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kubectl run --generator=run-pod/v1 busybox --rm -ti --labels="access=true" --image=busybox -- /bin/sh
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```
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请按照下面的例子在命令行中执行 `wget --spider --timeout=1 nginx`
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```
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Waiting for pod default/busybox-472357175-y0m47 to be running, status is Pending, pod ready: false
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Hit enter for command prompt
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/ # wget --spider --timeout=1 nginx
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Connecting to nginx (10.100.0.16:80)
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/ #
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```
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