1.coredns介绍
coredns是go编写的插件是dns，在k8s1.13后内置的默认dns。
github
2.coredns安装
容器安装 yaml来自
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| apiVersion: v1
kind: ConfigMap
metadata:
name: coredns
namespace: tool
data:
Corefile: |
.:53 {
log
errors
hosts {
8.8.8.9 TestCoreDNS.com
8.8.8.10 a.com
fallthrough
}
health {
lameduck 5s
}
prometheus :9153
forward . 114.114.114.114 8.8.8.8
cache 30
loop
reload
loadbalance
}
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: coredns
namespace: tool
labels:
k8s-app: coredns
kubernetes.io/name: "CoreDNS"
app.kubernetes.io/name: coredns
spec:
strategy:
type: RollingUpdate
rollingUpdate:
maxUnavailable: 1
selector:
matchLabels:
k8s-app: coredns
app.kubernetes.io/name: coredns
template:
metadata:
labels:
k8s-app: coredns
app.kubernetes.io/name: coredns
spec:
containers:
- name: coredns
image: k8s.gcr.io/coredns:1.7.0
imagePullPolicy: IfNotPresent
resources:
limits:
memory: 170Mi
requests:
cpu: 100m
memory: 70Mi
args: [ "-conf", "/etc/coredns/Corefile" ]
volumeMounts:
- name: config-volume
mountPath: /etc/coredns
readOnly: true
ports:
- containerPort: 53
name: dns
protocol: UDP
- containerPort: 53
name: dns-tcp
protocol: TCP
- containerPort: 9153
name: metrics
protocol: TCP
livenessProbe:
httpGet:
path: /health
port: 8080
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
dnsPolicy: Default
volumes:
- name: config-volume
configMap:
name: coredns
items:
- key: Corefile
path: Corefile
---
apiVersion: v1
kind: Service
metadata:
name: coredns
namespace: tool
annotations:
prometheus.io/port: "9153"
prometheus.io/scrape: "true"
labels:
k8s-app: coredns
kubernetes.io/cluster-service: "true"
kubernetes.io/name: "CoreDNS"
app.kubernetes.io/name: coredns
spec:
selector:
k8s-app: coredns
app.kubernetes.io/name: coredns
ports:
- name: dns
port: 53
protocol: UDP
- name: dns-tcp
port: 53
protocol: TCP
- name: metrics
port: 9153
protocol: TCP
|
3.coredns配置
- errors:错误信息到标准输出
- health:自身健康状态报告
- ready:可读性检查
- kubernetes:提供集群内服务解析能力
- prometheus:开启监控
- forward:当查询域名不在本配置中请求转发到指定的dns服务器
- cache:dns缓存
- loop:环路检测
- reload:自动重新加载corefile
- loadbalance:循环dns负载均衡器
4.验证
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| [root@node1 ~]# dig @10.233.92.7 a.com # hosts
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.10 <<>> @10.233.92.7 a.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25381
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;a.com. IN A
;; ANSWER SECTION:
a.com. 30 IN A 8.8.8.10
;; Query time: 0 msec
;; SERVER: 10.233.92.7#53(10.233.92.7)
;; WHEN: 三 12月 07 15:57:39 CST 2022
;; MSG SIZE rcvd: 55
[root@node1 ~]# dig @10.233.92.7 qq.com # 外网
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.10 <<>> @10.233.92.7 qq.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 30478
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;qq.com. IN A
;; ANSWER SECTION:
qq.com. 30 IN A 123.151.137.18
qq.com. 30 IN A 61.129.7.47
qq.com. 30 IN A 183.3.226.35
;; Query time: 13 msec
;; SERVER: 10.233.92.7#53(10.233.92.7)
;; WHEN: 三 12月 07 15:57:44 CST 2022
;; MSG SIZE rcvd: 101
|