Integrate Network Policy on Flannel

[rbrtbnfgl]

This issue is used to track a possible integration of https://github.com/kubernetes-sigs/kube-network-policies on Flannel.

[manuelbuil]

It'd be cool to have a config flag that if true, deploys it. It would provide the last missing piece for Flannel (at least in Linux) to be a complete CNI plugin

[rbrtbnfgl]

With the manifest edited on this way the kube-network-policies container is deployed inside the flannel Daemonset

apiVersion: v1
kind: Namespace
metadata:
  labels:
    k8s-app: flannel
    pod-security.kubernetes.io/enforce: privileged
  name: kube-flannel
---
apiVersion: v1
kind: ServiceAccount
metadata:
  labels:
    k8s-app: flannel
  name: flannel
  namespace: kube-flannel
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    k8s-app: flannel
  name: flannel
rules:
- apiGroups:
  - ""
  resources:
  - nodes
  - pods
  - namespaces
  verbs:
  - get
  - list
  - watch
- apiGroups:
  - ""
  resources:
  - nodes/status
  verbs:
  - patch
- apiGroups:
  - networking.k8s.io
  resources:
  - networkpolicies
  verbs:
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    k8s-app: flannel
  name: flannel
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: flannel
subjects:
- kind: ServiceAccount
  name: flannel
  namespace: kube-flannel
---
apiVersion: v1
data:
  cni-conf.json: |
    {
      "name": "cbr0",
      "cniVersion": "0.3.1",
      "plugins": [
        {
          "type": "flannel",
          "delegate": {
            "hairpinMode": true,
            "isDefaultGateway": true
          }
        },
        {
          "type": "portmap",
          "capabilities": {
            "portMappings": true
          }
        }
      ]
    }
  net-conf.json: |
    {
      "Network": "10.42.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }
kind: ConfigMap
metadata:
  labels:
    app: flannel
    k8s-app: flannel
    tier: node
  name: kube-flannel-cfg
  namespace: kube-flannel
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  labels:
    app: flannel
    k8s-app: flannel
    tier: node
  name: kube-flannel-ds
  namespace: kube-flannel
spec:
  selector:
    matchLabels:
      app: flannel
      k8s-app: flannel
  template:
    metadata:
      labels:
        app: flannel
        k8s-app: flannel
        tier: node
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: kubernetes.io/os
                operator: In
                values:
                - linux
      containers:
      - args:
        - --ip-masq
        - --kube-subnet-mgr
        command:
        - /opt/bin/flanneld
        env:
        - name: POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: EVENT_QUEUE_DEPTH
          value: "5000"
        image: docker.io/flannel/flannel:v0.25.4
        name: kube-flannel
        resources:
          requests:
            cpu: 100m
            memory: 50Mi
        securityContext:
          capabilities:
            add:
            - NET_ADMIN
            - NET_RAW
          privileged: false
        volumeMounts:
        - mountPath: /run/flannel
          name: run
        - mountPath: /etc/kube-flannel/
          name: flannel-cfg
        - mountPath: /run/xtables.lock
          name: xtables-lock
      - name: kube-network-policies
        image: registry.k8s.io/networking/kube-network-policies:v0.2.0
        args:
        - /bin/netpol
        - -v
        - "2"
        volumeMounts:
        - name: lib-modules
          mountPath: /lib/modules
          readOnly: true
        resources:
          requests:
            cpu: "100m"
            memory: "50Mi"
        securityContext:
          privileged: true
          capabilities:
            add: ["NET_ADMIN"]
      hostNetwork: true
      initContainers:
      - args:
        - -f
        - /flannel
        - /opt/cni/bin/flannel
        command:
        - cp
        image: docker.io/flannel/flannel-cni-plugin:v1.4.1-flannel1
        name: install-cni-plugin
        volumeMounts:
        - mountPath: /opt/cni/bin
          name: cni-plugin
      - args:
        - -f
        - /etc/kube-flannel/cni-conf.json
        - /etc/cni/net.d/10-flannel.conflist
        command:
        - cp
        image: docker.io/flannel/flannel:v0.25.4
        name: install-cni
        volumeMounts:
        - mountPath: /etc/cni/net.d
          name: cni
        - mountPath: /etc/kube-flannel/
          name: flannel-cfg
      priorityClassName: system-node-critical
      serviceAccountName: flannel
      tolerations:
      - effect: NoSchedule
        operator: Exists
      volumes:
      - name: lib-modules
        hostPath:
          path: /lib/modules
      - hostPath:
          path: /run/flannel
        name: run
      - hostPath:
          path: /opt/cni/bin
        name: cni-plugin
      - hostPath:
          path: /etc/cni/net.d
        name: cni
      - configMap:
          name: kube-flannel-cfg
        name: flannel-cfg
      - hostPath:
          path: /run/xtables.lock
          type: FileOrCreate
        name: xtables-lock

[manuelbuil]

what about adding it to the flannel charts with a boolean variable to enable it or not?

[rbrtbnfgl]

yes we could also integrate it within the chart.

[gitlayzer]

Hey man, can I understand that this is the support of NetworkPolicy in Flannel?

[rbrtbnfgl]

Flannel doesn't support network policy by itself. This is an integration with another project. If you install flannel using the helm chart and configuring it how is described here https://github.com/flannel-io/flannel/blob/master/Documentation/netpol.md the flannel pod will run with an additional container that manages the network policy with this you can run Flannel as CNI and also you can have the network policy.

[gitlayzer]

Flannel 本身不支持网络策略。这是与另一个项目的集成。如果您使用 helm chart 安装 flannel 并按照此处https://github.com/flannel-io/flannel/blob/master/Documentation/netpol.md所述进行配置，则 flannel pod 将与管理网络策略的附加容器一起运行，这样您就可以将 Flannel 作为 CNI 运行，也可以拥有网络策略。

Very clear, thank you.