Kubernetes DNS

DNS for Services and Pods
Service
- A/AAAA - my-svc.my-namespace.svc.cluster-domain.example
- SRV - _my-port-name._my-port-protocol.my-svc.my-namespace.svc.cluster-domain.example
Pod
- A/AAAA
  - <pod-ip-address>.my-namespace.pod.cluster-domain.example
  - 172-17-0-3.default.pod.cluster.local
- hostname, subdomain
  - <hostname>.<subdomain>.my-namespace.svc.cluster-domain.example
- setHostnameAsFQDN - 1.19 Alpha
pod.spec.dnsPolicy
- Default
  - 从运行节点集成
- ClusterFirst
  - 集群域名直接解析
  - 非集群域名转发到 node 指定的 dns 上游
- ClusterFirstWithHostNet
  - 用于 hostNetwork
- None
  - 忽略 K8S 环境下的 DNS 配置
  - 通过 dnsConfig 配置

apiVersion: v1
kind: Pod
metadata:
  name: busybox
  namespace: default
spec:
  containers:
    - image: busybox:1.28
      command:
        - sleep
        - '3600'
      imagePullPolicy: IfNotPresent
      name: busybox
  restartPolicy: Always
  hostNetwork: true
  # DNS 策略
  dnsPolicy: ClusterFirstWithHostNet
  # 自定义 DNS 配置 - 生成 /etc/resolv.conf
  # dnsPolicy: None
  dnsConfig:
    nameservers:
      - 1.2.3.4
    searches:
      - ns1.svc.cluster-domain.example
      - my.dns.search.suffix
    options:
      - name: ndots
        value: '2'
      - name: edns0

优先自定义 DNS

修改 resolve.conf 顺序
带上全部选项

spec:
  dnsPolicy: None
  dnsConfig:
    # reorder
    nameservers:
      - 10.43.0.153 # 希望优先解析的 DNS
      - 10.43.0.10 # kube-dns
    searches:
      - dev-system.svc.cluster.local
      - svc.cluster.local
      - cluster.local
    options:
      - name: ndots
        value: '5'

优先自定义 DNS​

优先自定义 DNS