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