我正在尝试解决我们的K8群集v1.19中的DNS问题。有3个节点（1个控制器，2个工人）全部使用带有Metallb的Calico网络运行香草Ubuntu 20.04，以实现入站负载平衡。这些都是在内部托管的，可以完全访问Internet。在它前面还有一个代理服务器（Traefik），用于处理K8群集的SSL和基础结构中的其他服务。
这个问题发生在我升级了连接到Redis Pod的Pod的头盔图时，但是过去36天内一直很乐意运行。
其中一个Pod的日志中显示一个错误，无法确定Redis Pod的位置：
2020-11-09 00:00:00 [1] [verbose]: [Cache] Attempting connection to redis.
2020-11-09 00:00:00 [1] [verbose]: [Cache] Successfully connected to redis.
2020-11-09 00:00:00 [1] [verbose]: [PubSub] Attempting connection to redis.
2020-11-09 00:00:00 [1] [verbose]: [PubSub] Successfully connected to redis.
2020-11-09 00:00:00 [1] [warn]: Secret key is weak. Please consider lengthening it for better security.
2020-11-09 00:00:00 [1] [verbose]: [Database] Connecting to database...
2020-11-09 00:00:00 [1] [info]: [Database] Successfully connected .
2020-11-09 00:00:00 [1] [verbose]: [Database] Ran 0 migration(s).
2020-11-09 00:00:00 [1] [verbose]: Sending request for public key.
Error: getaddrinfo EAI_AGAIN oct-2020-redis-master
at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:67:26) {
errno: -3001,
code: 'EAI_AGAIN',
syscall: 'getaddrinfo',
hostname: 'oct-2020-redis-master'
}
[ioredis] Unhandled error event: Error: getaddrinfo EAI_AGAIN oct-2020-redis-master
at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:67:26)
Error: connect ETIMEDOUT
at Socket.<anonymous> (/app/node_modules/ioredis/built/redis/index.js:307:37)
at Object.onceWrapper (events.js:421:28)
at Socket.emit (events.js:315:20)
at Socket.EventEmitter.emit (domain.js:486:12)
at Socket._onTimeout (net.js:483:8)
at listOnTimeout (internal/timers.js:554:17)
at processTimers (internal/timers.js:497:7) {
errorno: 'ETIMEDOUT',
code: 'ETIMEDOUT',
syscall: 'connect'
}
我已经完成了https://kubernetes.io/docs/tasks/administer-cluster/dns-debugging-resolution/
中列出的步骤ubuntu@k8-01:~$ kubectl exec -i -t dnsutils -- nslookup kubernetes.default
;; connection timed out; no servers could be reached
command terminated with exit code 1
ubuntu@k8-01:~$ kubectl get pods --namespace=kube-system -l k8s-app=kube-dns
NAME READY STATUS RESTARTS AGE
coredns-f9fd979d6-lfm5t 1/1 Running 17 37d
coredns-f9fd979d6-sw2qp 1/1 Running 18 37d
ubuntu@k8-01:~$ kubectl logs --namespace=kube-system -l k8s-app=kube-dns
CoreDNS-1.7.0
linux/amd64, go1.14.4, f59c03d
[INFO] Reloading
[INFO] plugin/health: Going into lameduck mode for 5s
[INFO] plugin/reload: Running configuration MD5 = 3d3f6363f05ccd60e0f885f0eca6c5ff
[INFO] Reloading complete
[INFO] 10.244.210.238:34288 - 28733 "A IN oct-2020-redis-master.default.svc.cluster.local. udp 75 false 512" NOERROR qr,aa,rd 148 0.001300712s
[INFO] 10.244.210.238:44532 - 12032 "A IN oct-2020-redis-master.default.svc.cluster.local. udp 75 false 512" NOERROR qr,aa,rd 148 0.001279312s
[INFO] 10.244.210.235:44595 - 65094 "A IN oct-2020-redis-master.default.svc.cluster.local. udp 75 false 512" NOERROR qr,aa,rd 148 0.000163001s
[INFO] 10.244.210.235:55945 - 20758 "A IN oct-2020-redis-master.default.svc.cluster.local. udp 75 false 512" NOERROR qr,aa,rd 148 0.000141202s
ubuntu@k8-01:~$ kubectl get services --all-namespaces
NAMESPACE NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
default oct-2020-api ClusterIP 10.107.89.213 <none> 80/TCP 37d
default oct-2020-nginx-ingress-controller LoadBalancer 10.110.235.175 192.168.2.150 80:30194/TCP,443:31514/TCP 37d
default oct-2020-nginx-ingress-default-backend ClusterIP 10.98.147.246 <none> 80/TCP 37d
default oct-2020-redis-headless ClusterIP None <none> 6379/TCP 37d
default oct-2020-redis-master ClusterIP 10.109.58.236 <none> 6379/TCP 37d
default oct-2020-webclient ClusterIP 10.111.204.251 <none> 80/TCP 37d
default kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 37d
kube-system coredns NodePort 10.101.104.114 <none> 53:31245/UDP 15h
kube-system kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP,9153/TCP 37d
当我进入广告连播时：
/app # grep "nameserver" /etc/resolv.conf
nameserver 10.96.0.10
/app # nslookup
BusyBox v1.31.1 () multi-call binary.
Usage: nslookup [-type=QUERY_TYPE] [-debug] HOST [DNS_SERVER]
Query DNS about HOST
QUERY_TYPE: soa,ns,a,aaaa,cname,mx,txt,ptr,any
/app # ping 10.96.0.10
PING 10.96.0.10 (10.96.0.10): 56 data bytes
^C
--- 10.96.0.10 ping statistics ---
3 packets transmitted, 0 packets received, 100% packet loss
/app # nslookup oct-20-redis-master
;; connection timed out; no servers could be reached
任何有关故障排除的想法将不胜感激。
答案 0 :(得分：1)
要回答我自己的问题，我删除了DNS吊舱，然后又重新工作了。命令如下：
let dateStr = "20201110011515";
let year = dateStr.substring(0, 4);
let month = dateStr.substring(4, 6);
let day = dateStr.substring(6, 8);
let hour = dateStr.substring(8, 10);
let minute = dateStr.substring(10, 12);
let second = dateStr.substring(12, 14);
return new Date(year, month, day, hour, minute, second);
这并没有解决为什么发生这种情况，或者为什么K8没有检测到这些吊舱有问题并重新创建它们的潜在问题。我将继续研究这个问题，并在DNS窗格上放置更多工具，以查看实际上是什么导致了此问题。
如果有人对仪器的连接或特定用途有任何想法，将不胜感激。
答案 1 :(得分：0)
这是我们测试dns的方式
创建下面的部署
apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
app: nginx
spec:
ports:
- port: 80
name: web
clusterIP: None
selector:
app: nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: web
labels:
app: nginx
spec:
serviceName: "nginx"
replicas: 2
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: k8s.gcr.io/nginx-slim:0.8
ports:
- containerPort: 80
name: web
volumeMounts:
- name: www
mountPath: /usr/share/nginx/html
volumes:
- name: www
emptyDir:
运行以下测试
master $ kubectl get po
NAME READY STATUS RESTARTS AGE
web-0 1/1 Running 0 1m
web-1 1/1 Running 0 1m
master $ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 35m
nginx ClusterIP None <none> 80/TCP 2m
master $ kubectl run -i --tty --image busybox:1.28 dns-test --restart=Never --rm
If you don't see a command prompt, try pressing enter.
/ # nslookup nginx
Server: 10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local
Name: nginx
Address 1: 10.40.0.1 web-0.nginx.default.svc.cluster.local
Address 2: 10.40.0.2 web-1.nginx.default.svc.cluster.local
/ #
/ # nslookup web-0.nginx
Server: 10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local
Name: web-0.nginx
Address 1: 10.40.0.1 web-0.nginx.default.svc.cluster.local
/ # nslookup web-0.nginx.default.svc.cluster.local
Server: 10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local
Name: web-0.nginx.default.svc.cluster.local
Address 1: 10.40.0.1 web-0.nginx.default.svc.cluster.local