容器磁盘上的文件的生命周期是短暂的，这就使得在容器中运行重要应用时会出现一些问题。首先，当容器崩溃时，kubelet会重启它，但是容器中国的文件将丢失–容器以干净的状态（镜像最初的状态）重新启动。其次在pod中同时运行多个容器时，这些容器之间通常需要共享文件。kubernetes中的volume抽象就很好的解决这些问题。
Kubernetes中的卷有明确的寿命，与封装它的pod相同。所以，卷的生命比pod中的所有容器都长，当这个容器重启时数据仍然得以保存。当然,当pod不再存在时，卷也将不复存在。也许更重要的是，kubernetes支持多种类型的卷，pod可以同时使用任意数量的卷。
kubernetes支持以下类型的卷
emptyDir
当pod被分配给节点时，首先创建emptyDir卷，并且只要该pod在该节点上运行，该卷就会存在。正如卷的名字所述，它最初是空的。Pod中 的容器可以读取和写入emptyDir卷中的相同文件，尽管该卷可以挂载到每个容器中的相同的或者不同的路径上。当出于任何原因从节点中删除pod时，emptyDir中的数据将被永久删除。
=注意：容器崩溃不会从节点中移除pod,因此emptyDir卷中的数据在容器崩溃时是安全的
emptyDir的用法：
- 暂存空间，例如用于基于磁盘的合并排序
- 用作长时间计算崩溃恢复时的检查点
- Web服务器容器提供数据时，保存内容管理器容器中提取的文件。
- 这里的image得从node节点的docker images中进行查看，然后选择（因为是从私有仓库中下载下来的），因为没有找到合适的 所有在下面的运行中开始出错了
apiVersion: v1
kind: Pod
metadata:
name: test-pd
spec:
containers:
- image: registry.aliyuncs.com/google_containers/pause
name: test-container
volumeMounts:
- name: cache-volume
mountPath: /cache
volumes:
- name: cache-volume
emptyDir: {}
[root@master volume]# vim em.yaml
[root@master volume]# kubectl apply -f em.yaml
pod/test-pd configured
[root@master volume]# kubectl get pod
NAME READY STATUS RESTARTS AGE
ds-test-r7ct2 1/1 Running 0 8m20s
ds-test-sp7z4 1/1 Running 0 8m20s
ds-test-wm84n 1/1 Running 0 8m21s
hello-1623503580-5qx6h 0/1 Completed 0 2m24s
hello-1623503640-4xdsv 0/1 Completed 0 84s
hello-1623503700-kpwz6 0/1 Completed 0 23s
test-pd 1/1 Running 0 6m29s
出现的问题
[root@master volume]# kubectl exec test-pd -it -- /bin/sh
OCI runtime exec failed: exec failed: container_linux.go:380: starting container process caused: exec: "/bin/sh": stat /bin/sh: no such file or directory: unknown
command terminated with exit code 126
[root@master volume]# kubectl exec -it test-pd /bin/sh
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
OCI runtime exec failed: exec failed: container_linux.go:380: starting container process caused: exec: "/bin/sh": stat /bin/sh: no such file or directory: unknown
command terminated with exit code 126
[root@master volume]# kubectl exec test-pd -it -- /bin/sh
OCI runtime exec failed: exec failed: container_linux.go:380: starting container process caused: exec: "/bin/sh": stat /bin/sh: no such file or directory: unknown
command terminated with exit code 126
[root@master volume]#
nfs
数据卷emptydir是本地存储，pod重启， 数据就不存在了，要使pod重启数据还存在，需要对数据进行持久化存储。
1.nfs 网络存储
pod重启，数据还存在
第一步 找一台服务器专门作为nfs服务端
（1）安装nfs
[root@kuangshen ~]# yum install -y nfs-utils
（2） 设置挂载路径
# 存储目录，*允许所有人连接，rw读写权限，sync文件同时写入硬盘及内存，no_root_squash 使用者root用户自动修改为普通用户
vim /etc/exports
/data/nfs *(rw,no_root_squash,sync)#也可以写成图片上的内容
（3）挂载路径需要创建出来
[root@kuangshen ~]# vim /etc/exports
[root@kuangshen ~]# mkdir /data
[root@kuangshen ~]# cd /data
[root@kuangshen data]# mkdir nfs
[root@kuangshen data]# ls
nfs
第二步 在k8s集群node节点安装nfs
[root@node01 ~]# yum install -y nfs-utils
[root@node02 ~]# yum install -y nfs-utils
[root@node03 ~]# yum install -y nfs-utils
第三步 在nfs服务器启动nfs服务
[root@kuangshen data]# systemctl start nfs
[root@kuangshen data]# ps -ef | grep nfs
root 32603 2 0 19:31 ? 00:00:00 [nfsd4_callbacks]
root 32609 2 0 19:31 ? 00:00:00 [nfsd]
root 32610 2 0 19:31 ? 00:00:00 [nfsd]
root 32611 2 0 19:31 ? 00:00:00 [nfsd]
root 32612 2 0 19:31 ? 00:00:00 [nfsd]
root 32613 2 0 19:31 ? 00:00:00 [nfsd]
root 32614 2 0 19:31 ? 00:00:00 [nfsd]
root 32615 2 0 19:31 ? 00:00:00 [nfsd]
root 32616 2 0 19:31 ? 00:00:00 [nfsd]
root 32719 30878 0 19:32 pts/0 00:00:00 grep --color=auto nfs
第四步 在k8s集群部署应用使用nfs持久化网络存储
[root@master pv]# vim nfs-nginx.yaml #这里粘贴的内容就是下面nfs-nginx.yaml文件里面的内容
[root@master pv]# kubectl apply -f nfs-nginx.yaml
deployment.apps/nginx-dep1 created
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-dep1
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx
volumeMounts:
- name: html
mountPath: /usr/share/nginx/html
ports:
- containerPort: 80
volumes:
- name: html
nfs:
server: nfs服务端的ip地址
path: /data/nfs
[root@master pv]# kubectl get pods
NAME READY STATUS RESTARTS AGE
ds-test-489bb 1/1 Running 0 2d
ds-test-4rvcr 1/1 Running 0 2d
ds-test-nx6kt 1/1 Running 0 2d
hello-1623412080-9hq98 0/1 Completed 0 3m3s
hello-1623412140-dgssl 0/1 Completed 0 2m3s
hello-1623412200-9mqss 0/1 Completed 0 63s
hello-1623412260-ffkxx 0/1 ContainerCreating 0 12s
nginx-dep1-7d6c86b544-gc4cr 0/1 ContainerCreating 0 8m35s
查看日志出的错误：
[root@master pv]# kubectl describe pod nginx-dep1-7d6c86b544-gc4cr
Warning FailedMount 23s (x2 over 4m41s) kubelet MountVolume.SetUp failed for volume "wwwroot" : mount failed: exit status 32
Mounting command: mount
Mounting arguments: -t nfs 8.140.99.18:/data/nfs /var/lib/kubelet/pods/b1e30a93-e417-486f-925d-8a079d7ff06d/volumes/kubernetes.io~nfs/wwwroot
Output: mount.nfs: Connection timed out
Warning FailedMount 7s (x4 over 6m56s) kubelet Unable to attach or mount volumes: unmounted volumes=[wwwroot], unattached volumes=[wwwroot default-token-8vnf8]: timed out waiting for the condition
还没能解决这个问题
下面这截图是成功执行的样子
PV和PVC
1.PV：持久化存储，对存储资源进行抽象，对外提供可以调用的地方。（生产者）
2.PVC：用于调用不需要关系内部实现细节（消费者）
3.实现流程
pvc.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-dep1
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx
volumeMounts:
- name: wwwroot
mountPath: /usr/share/nginx/html
ports:
- containerPort: 80
volumes:
- name: wwwroot
persistentVolumeClaim:
claimName: my-pvc
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: my-pvc
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 5Gi
pv.ymal
apiVersion: v1
kind: PersistentVolume
metadata:
name: my-pv
spec:
capacity:
storage: 5Gi
accessModes:
- ReadWriteMany
nfs:
path: /data/nfs
server: nfs服务端的ip地址
[root@master pv]# rz
[root@master pv]# ls
pvc.yaml pv.yaml
[root@master pv]# rz
[root@master pv]# kubectl apply -f pv.yaml
persistentvolume/my-pv unchanged
[root@master pv]# kubectl get pv,pvc
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
persistentvolume/my-pv 5Gi RWX Retain Bound default/my-pvc 3h4m
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
persistentvolumeclaim/my-pvc Bound my-pv 5Gi RWX 3h6m
persistentvolumeclaim/myclaim Pending nfs 20m
[root@master pv]# kubectl get pods
NAME READY STATUS RESTARTS AGE
ds-test-489bb 1/1 Running 0 3d
ds-test-4rvcr 1/1 Running 0 3d
ds-test-nx6kt 1/1 Running 0 3d
hello-1623500940-lf9vs 0/1 Completed 0 2m38s
hello-1623501000-hxnqg 0/1 Completed 0 98s
hello-1623501060-l5nlp 0/1 Completed 0 38s
nginx-dep1-69f5bb95b-585fr 0/1 ContainerCreating 0 4m12s
nginx-dep1-69f5bb95b-8smrj 0/1 ContainerCreating 0 4m12s
nginx-dep1-69f5bb95b-wfzxz 0/1 ContainerCreating 0 4m12s
weave-scope-agent-ui-44tjs 1/1 Running 0 28h
weave-scope-agent-ui-crnmn 0/1 ImagePullBackOff 0 28h
weave-scope-agent-ui-d6tm2 1/1 Running 0 28h
weave-scope-agent-ui-rwpcq 1/1 Running 0 28h
weave-scope-agent-ui1-cdwzs 1/1 Running 0 28h
weave-scope-agent-ui1-chkr2 0/1 ImagePullBackOff 0 28h
weave-scope-agent-ui1-mwqjb 1/1 Running 0 28h
weave-scope-agent-ui1-tjbmb 1/1 Running 0 28h
weave-scope-agent-ui3-bp7lc 0/1 ImagePullBackOff 0 28h
weave-scope-agent-ui3-j6tvt 1/1 Running 0 28h
weave-scope-agent-ui3-khw2t 1/1 Running 0 28h
weave-scope-agent-ui3-wq5fw 1/1 Running 0 28h
weave-scope-cluster-agent-ui3-5b8fcd7c97-f2p84 1/1 Running 0 28h
weave-scope-frontend-ui3-684bccd8f4-8742z 1/1 Running 0 28h
web3-deploy-6799fc88d8-p74vt 1/1 Running 0 25h
[root@master pv]#
错误信息
[root@master pv]# kubectl describe pod nginx-dep1-69f5bb95b-585fr #查看节点详细信息
Normal Scheduled 6m53s default-scheduler Successfully assigned default/nginx-dep1-69f5bb95b-585fr to node02
Warning FailedMount 2m36s kubelet MountVolume.SetUp failed for volume "my-pv" : mount failed: exit status 32
Mounting command: mount
Mounting arguments: -t nfs 8.140.99.18:/data/nfs /var/lib/kubelet/pods/10f49896-989e-4075-9b11-f3533640d602/volumes/kubernetes.io~nfs/my-pv
Output: mount.nfs: Connection timed out
Warning FailedMount 21s (x3 over 4m51s) kubelet Unable to attach or mount volumes: unmounted volumes=[wwwroot], unattached volumes=[wwwroot default-token-8vnf8]: timed out waiting for the condition
目前 nfs和pv pvc都未能成功，网上找的资料也未能解决这个问题
这是操作成功应该有的截图
知识点补充删除所有pod的命令
kubectl delete pod --all
集群资源监控
1.监控指标
- 集群监控
- 节点资源利用率
- 节点数
- 运行pods
- Pod监控
- 容器指标
- 应用程序
2.监控平台搭建方案
prometheus + Grafana
(1)prometheus
- 开源的
- 监控、报警、数据库
- 以HTTP协议周期性抓取被监控组件状态
- 不需要很复杂的集成过程，使用http接口接入就可以了
(2) Grafana
- 开源的数据分析和可视化工具
- 支持多种数据源
B站学习网址：k8s教程由浅入深-尚硅谷_哔哩哔哩_bilibili