Network Policy介绍
Network Policy介绍
- 网络策略(NetworkPolicy)是一种关于 Pod 间及与其他Network Endpoints间所允许的通信规则的规范。
- NetworkPolicy 资源使用 标签 选择 Pod,并定义选定 Pod 所允许的通信规则。
- 网络策略通过网络插件来实现。要使用网络策略,用户必须使用支持 NetworkPolicy 的网络解决方案。
- 默认情况下,Pod间是非隔离的,它们接受任何来源的流量。
- Pod 可以通过相关的网络策略进行隔离。一旦命名空间中有网络策略选择了特定的 Pod,该 Pod 会拒绝网络策略所不允许的连接。(命名空间下其他未被网络策略所选择的 Pod 会继续接收所有的流量)
- 网络策略不会冲突,它们是附加的。如果任何一个或多个策略选择了一个 Pod, 则该 Pod 受限于这些策略的 ingress/egress 规则的并集。因此策略的顺序并不会影响策略的结果。
Network Policy 简单例子
首先分别在两个namespace创建pod:
apiVersion: v1 kind: Namespace metadata: name: network-policy-1 --- apiVersion: v1 kind: Namespace metadata: name: network-policy-2 --- apiVersion: v1 kind: Pod metadata: name: busybox-1 namespace: network-policy-1 labels: name: busybox-1 spec: containers: - name: busybox image: busybox:1.28 command: ['sh','-c','sleep 3600'] imagePullPolicy: IfNotPresent --- apiVersion: v1 kind: Pod metadata: name: busybox-2 namespace: network-policy-2 labels: name: busybox-2 spec: containers: - name: busybox image: busybox:1.28 command: ['sh','-c','sleep 3600'] imagePullPolicy: IfNotPresent
未部署NetworkPolicy之前,两个不同namespace的pod是可以相互通信的。
busybox-2 1/1 Running 0 23s 10.244.139.253 k8s-calico-node02 <none> <none> ❯ kubectl get pod -n network-policy-1 -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES busybox-1 1/1 Running 0 26s 10.244.195.91 k8s-calico-master <none> <none> #刚开始busybox-1和busybox-2是可以互相访问的 ❯ kubectl exec -n network-policy-1 busybox-1 -- ping 10.244.139.253 PING 10.244.139.253 (10.244.139.253): 56 data bytes 64 bytes from 10.244.139.253: seq=0 ttl=62 time=1.220 ms 64 bytes from 10.244.139.253: seq=1 ttl=62 time=1.079 ms 64 bytes from 10.244.139.253: seq=2 ttl=62 time=1.093 ms 64 bytes from 10.244.139.253: seq=3 ttl=62 time=1.044 ms ❯ kubectl exec -n network-policy-2 busybox-2 -- ping 10.244.195.91 PING 10.244.195.91 (10.244.195.91): 56 data bytes 64 bytes from 10.244.195.91: seq=0 ttl=62 time=0.998 ms 64 bytes from 10.244.195.91: seq=1 ttl=62 time=1.230 ms
默认拒绝所有入口流量
部署一条NetworkPolicy,作用在namespace为network-policy-1的pod上,禁止入访流量:
--- apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: default-deny-ingress namespace: network-policy-1 #networkPolicy配置在busybox-1的namespace,不允许外部流量主动访问 spec: podSelector: {} #policyType写了Ingress,在Ingress里没写内容,表示拒绝所有ingress流量 policyTypes: - Ingress
#busybox-1可以访问busybox-2 ❯ kubectl exec -n network-policy-1 busybox-1 -- ping 10.244.139.253 PING 10.244.139.253 (10.244.139.253): 56 data bytes 64 bytes from 10.244.139.253: seq=0 ttl=62 time=2.895 ms 64 bytes from 10.244.139.253: seq=1 ttl=62 time=0.605 ms #busybox-2无法访问busybox-1 ❯ kubectl exec -n network-policy-2 busybox-2 -- ping 10.244.195.91 ^C
默认允许所有入口流量
在前面那条NetworkPolicy不删除的同时,添加一条允许所有入访流量的networkPolicy,流量最终会允许。可以看到只要流量能够匹配到一条满足放行的NetworkPolicy,则流量就会被放行。
--- apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-all-ingress namespace: network-policy-1 spec: podSelector: {} #policyType写了Ingress,在ingress写了{},表示放行所有ingress流量 ingress: - {} policyTypes: - Ingress
#两条networkPolicy同时存在 ❯ kubectl get -n network-policy-1 networkpolicies.networking.k8s.io NAME POD-SELECTOR AGE allow-all-ingress <none> 27s default-deny-ingress <none> 94s #busybox-2重新可以访问busybox-1了 ❯ kubectl exec -n network-policy-2 busybox-2 -- ping 10.244.195.91 PING 10.244.195.91 (10.244.195.91): 56 data bytes 64 bytes from 10.244.195.91: seq=0 ttl=62 time=1.057 ms 64 bytes from 10.244.195.91: seq=1 ttl=62 time=0.872 ms
Network Policy 综合例子
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: network-policy-cidr namespace: network-policy-1 spec: podSelector: matchLabels: name: centos-1 #只有pod的label为name=centos-1的pod才会收到下面的policy的约束 policyTypes: - Ingress ingress: - from: - namespaceSelector: matchLabels: project: centos-2 - podSelector: matchLabels: name: centos-2 - ipBlock: cidr: 10.244.0.0/16 #只允许源是10.244.0.0/16的网段来访问 except: - 10.244.195.0/24 #源是10.244.195.0/24的网段不允许来访问 ports: - protocol: TCP port: 80 #只有80端口允许被访问
查看生成的具体规则
❯ kubectl describe -n network-policy-1 networkpolicies. Name: network-policy-cidr Namespace: network-policy-1 Created on: 2020-05-19 21:01:49 +0800 CST Labels: <none> Annotations: kubectl.kubernetes.io/last-applied-configuration: {"apiVersion":"networking.k8s.io/v1","kind":"NetworkPolicy","metadata":{"annotations":{},"name":"network-policy-cidr","namespace":"network... Spec: PodSelector: name=centos-1 Allowing ingress traffic: To Port: 80/TCP From: NamespaceSelector: project=centos-2 From: PodSelector: name=centos-2 From: IPBlock: CIDR: 10.244.0.0/16 Except: 10.244.195.0/24
现在尝试在不同条件下(namespace label,pod label,pod ip地址)去访问名为centos-1的pod,以下表格为整理出的不同条件下的访问结果:(这里的策略是或的关系,只要满足一个就放行)
以下黑色字体加粗的为不满足要求的条件:
namespace label | pod label | pod CIDR | 访问centos1的80端口 | ping |
project=centos-2 | name=centos-2 | 10.244.139.0/24 | 可以 | 不可以 |
project=centos-2 | name=centos-2 | 10.244.195.0/24 | 可以 | 不可以 |
project=centos-2 | 无 | 10.244.139.0/24 | 可以 | 不可以 |
无 | name=centos-2 | 10.244.139.0/24 | 可以 | 不可以 |
无 | 无 | 10.244.139.0/24 | 可以 | 不可以 |
无 | name=centos-2 | 10.244.195.0/24 | 可以 | 不可以 |
project=centos-2 | 无 | 10.244.195.0/24 | 可以 | 不可以 |
无 | 无 | 10.244.195.0/24 | 不可以 | 不可以 |
Network Policy 与和或的关系
这个策略表示放行namespace label为project=centos2这个命名空间中的pod,或者pod label为name=centos2的pod:
ingress: - from: - namespaceSelector: matchLabels: project: centos-2 - podSelector: matchLabels: name: centos-2
注意观察,podSelector
前面没有-
,此时namespaceSelector和podSelector是与的关系,表示放行的是在namespace label为project=centos2这个命名空间中,并且pod的label为name=centos2的pod。
ingress: - from: - namespaceSelector: matchLabels: project: centos-2 podSelector: matchLabels: name: centos-2
NetworkPolicy可视化展示
通过https://orca.tufin.io/netpol/ 网站上可以对networkPolicy做可视化展示:
ingress:egress: