无法使用hostNetwork解析容器内的Kubernetes服务名称

问题描述

使用hostNetwork时无法使用Kubernetes内部DNS：

/ test# nslookup echo
Server:    10.96.0.10
Address 1: 10.96.0.10

nslookup: can't resolve 'echo'

没有hostNetwork：

/ test# nslookup echo
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      echo
Address 1: 10.98.232.198 echo.default.svc.cluster.local

未升级的裸机上的Kubernetes 1.18.5（未全新安装）。

完整配置：

apiVersion: apps/v1
kind: DaemonSet
Metadata:
  name: test
  labels:
    app: test

spec:
  selector:
    matchLabels:
      app: test

  template:
    Metadata:
      labels:
        app: test

    spec:
      hostNetwork: true
      dnsPolicy: ClusterFirstWithHostNet

      containers:
      - image: busyBox:1.28
        command:
          - sleep
          - "3600"
        imagePullPolicy: IfNotPresent
        name: busyBox

---

apiVersion: apps/v1
kind: Deployment
Metadata:
  name: echo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: echo
  template:
    Metadata:
      labels:
        app: echo
    spec:
      containers:
        - name: echo
          image: jmalloc/echo-server
          ports:
            - name: http-port
              containerPort: 8080
---
apiVersion: v1
kind: Service
Metadata:
  name: echo
spec:
  ports:
    - name: http-port
      port: 80
      targetPort: http-port
      protocol: TCP
  selector:
    app: echo

解决方法

全新安装的Kubernetes 1.19.0解决了此问题。