K8s基础
目录
base
#使用glusterfs做存储，不懂glusterfs的请参考其他文章
命名空间
label
给节点打标签label
root@ubuntu-200470-1:~/pod# kubectl get node
NAME STATUS ROLES AGE VERSION
master Ready control-plane 22d v1.24.10
work1 Ready <none> 22d v1.24.10
work2 Ready <none> 22d v1.24.10
#给节点1 work1打上 nodename=node01
root@ubuntu-200470-1:~/pod# kubectl label nodes work1 nodename=node01
node/work1 labeled
#查看效果
root@ubuntu-200470-1:~/pod# kubectl get node --show-labels=true
NAME STATUS ROLES AGE VERSION LABELS
master Ready control-plane 22d v1.24.10 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=master,kubernetes.io/os=linux,node-role.kubernetes.io/control-plane=,node.kubernetes.io/exclude-from-external-load-balancers=
work1 Ready <none> 22d v1.24.10 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=work1,kubernetes.io/os=linux,nodename=node01
work2 Ready <none> 22d v1.24.10 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=work2,kubernetes.io/os=linux
#使用 例如在dp
apiVersion: apps/v1
kind: Deployment
metadata:
name: dep-nginx-sel-node
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
ver: beta
spec:
containers:
- name: nginx
image: nginx:1.25.2-alpine
imagePullPolicy: IfNotPresent
nodeSelector:
nodename: node01
label svc
oot@ubuntu-200470-1:~/oct19# kubectl get svc nginx --show-labels NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE LABELS nginx ClusterIP None <none> 80/TCP 6h15m app=nginxlabelstest root@ubuntu-200470-1:~/oct19# kubectl label svc nginx version=1 service/nginx labeled root@ubuntu-200470-1:~/oct19# kubectl get svc nginx --show-labels NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE LABELS nginx ClusterIP None <none> 80/TCP 6h15m app=nginxlabelstest,version=1 root@ubuntu-200470-1:~/oct19# kubectl label svc nginx version- service/nginx unlabeled root@ubuntu-200470-1:~/oct19# kubectl get svc nginx --show-labels NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE LABELS nginx ClusterIP None <none> 80/TCP 6h16m app=nginxlabelstest root@ubuntu-200470-1:~/oct19#
controllers 控制器
控制器DaemonSet
控制器CronJob
Helm3
k8s-imagePullPolicy拉取策略
imagePullPolicy: Always 总是拉取 pull 以前好像是这个默认值 imagePullPolicy: IfNotPresent 默认值,本地有则使用本地镜像,不拉取 imagePullPolicy: Never 只使用本地镜像，从不拉取
k8s 进入pod shell
kubectl get pods #查看所有正在运行的pod NAME READY STATUS RESTARTS AGE nginx-56b8c64cb4-t97vb 1/1 Running 3 1d kubectl exec -it nginx-56b8c64cb4-t97vb -- /bin/bash #假如当前pod只有一个容器,运行以下命令即可 root@nginx-56b8c64cb4-t97vb:/# ps -ef UID PID PPID C STIME TTY TIME CMD root 1 0 0 14:45 ? 00:00:00 nginx: master process nginx -g daemon off; 假如一个pod里有多个容器,用--container or -c 参数。例如:假如这里有个Pod名为my-pod,这个Pod有两个容器,分别名为main-app 和 helper-app,下面的命令将打开到main-app的shell的容器里。 kubectl exec -it my-pod --container main-app -- /bin/bash
k8s删除pod
1、先删除pod2、再删除对应的deployment否则只是删除pod是不管用的，还会看到pod，因为deployment.yaml文件中定义了副本数量 实例如下： 删除pod [root@test2 ~]# kubectl get pod -n jenkins NAME READY STATUS RESTARTS AGE jenkins2-8698b5449c-grbdm 1/1 Running 0 8s [root@test2 ~]# kubectl delete pod jenkins2-8698b5449c-grbdm -n jenkins pod "jenkins2-8698b5449c-grbdm" deleted 查看pod仍然存储 [root@test2 ~]# kubectl get pod -n jenkins NAME READY STATUS RESTARTS AGE jenkins2-8698b5449c-dbqqb 1/1 Running 0 8s [root@test2 ~]# 删除deployment [root@test2 ~]# kubectl get deployment -n jenkins NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE jenkins2 1 1 1 1 17h [root@test2 ~]# kubectl delete deployment jenkins2 -n jenkins 再次查看pod消失 deployment.extensions "jenkins2" deleted [root@test2 ~]# kubectl get deployment -n jenkins No resources found. [root@test2 ~]# [root@test2 ~]# kubectl get pod -n jenkins No resources found.
[ k8s中正确删除一个pod k8s中正确删除一个pod ]
常见组件安装
安装Metrics server
hpa
coredns状态为ImagePullBackOff问题
kubectl get pods --all-namespaces
kube-system coredns-7f6cbbb7b8-knhl8 0/1 ImagePullBackOff 0 24h
kube-system coredns-7f6cbbb7b8-lt4k5 0/1 ImagePullBackOff 0 24h
解决办法：
确定pod所使用的镜像
kubectl get pods coredns-7f6cbbb7b8-knhl8 -n kube-system -o yaml | grep image
image: registry.aliyuncs.com/google_containers/coredns:v1.8.4
imagePullPolicy: IfNotPresent
- image: registry.aliyuncs.com/google_containers/coredns:v1.8.4
imageID: ""
message: Back-off pulling image "registry.aliyuncs.com/google_containers/coredns:v1.8.4"
root@k8s-master:~# docker pull registry.aliyuncs.com/google_containers/coredns:v1.8.4
Error response from daemon: manifest for registry.aliyuncs.com/google_containers/coredns:v1.8.4 not found: manifest unknown: manifest unknown
拉个latest 再别名
docker pull registry.aliyuncs.com/google_containers/coredns
root@k8s-master:~# docker images | grep coredns
registry.aliyuncs.com/google_containers/coredns latest 8d147537fb7d 3 months ago 47.6MB
强制 改一下 tag
root@k8s-master:~# docker tag 8d147537fb7d registry.aliyuncs.com/google_containers/coredns:v1.8.4
root@k8s-master:~# kubectl get pods --all-namespaces | grep coredns
kube-system coredns-7f6cbbb7b8-knhl8 1/1 Running 0 24h
kube-system coredns-7f6cbbb7b8-lt4k5 1/1 Running 0 24h
root@k8s-master:~#
root@k8s-master:~# kubectl get all -n kube-system
NAME READY STATUS RESTARTS AGE
pod/coredns-7f6cbbb7b8-knhl8 0/1 ImagePullBackOff 0 24h
pod/coredns-7f6cbbb7b8-lt4k5 0/1 ImagePullBackOff 0 24h
docker pull registry.aliyuncs.com/google_containers/coredns
k8s解决coredns 的ImagePullBackOff 和ErrImagePull 问题
https://stackoverflow.com/questions/53559291/kubernetes-coredns-in-crashloopbackoff
Kubernetes CoreDNS 状态是 CrashLoopBackOff 解决思路
CrashLoopBackOff的解决方法
记录一次修复k8s pod长时间处于CrashLoopBackOff状态问题
k8s启动Pod遇到CrashLoopBackOff的解决方法
k8s常见问题
pod无故重启
OOM
