前言

为什么要有数据管理？
因为：

• Docker 是不提供持久化的 ，容器是不稳定的；
• 一个容器一个服务；
• 多个容器可能要共享一块数据；
• docker容器每次创建都是新开一个容器，不必理会旧的容器什么状态。

这种情况下，每次的更新部署非常方便，但是这样一来所有的数据就需要持久化存储到宿主机里。就引出了docker的数据管理知识。

1、Dcoker 文件体系

docker 数据卷默认位置：

/var/lib/docker/volumes

挂载以后，目录是共享的；数据不应该放到容器中，而是要求宿主机分一块目录给容器用来存放数据。

删除容器，是不会删除volumes目录的（强制除外）

2、volume挂载案例

2.1、挂载运行一个容器实例

方法1

docker run -it --name centosTest -v /opt/data centos /bin/bash

此刻就进入了容器内部。

然后查看确实产生了 /opt/data 目录，在该目录下新建一个123 文件，并去查看宿主机目录下是否存在：

然后先查看 容器：

查看元数据及文件新增

[{"Id": "dee355965bca29c9355a5e9bff5132f89337b59b4e30c2459e89b6f64238ad2f","Created": "2023-08-06T11:12:05.096013057Z","Path": "/bin/bash","Args": [],"State": {"Status": "running","Running": true,"Paused": false,"Restarting": false,"OOMKilled": false,"Dead": false,"Pid": 14786,"ExitCode": 0,"Error": "","StartedAt": "2023-08-06T11:12:05.96660496Z","FinishedAt": "0001-01-01T00:00:00Z"},"Image": "sha256:5d0da3dc976460b72c77d94c8a1ad043720b0416bfc16c52c45d4847e53fadb6","ResolvConfPath": "/var/lib/docker/containers/dee355965bca29c9355a5e9bff5132f89337b59b4e30c2459e89b6f64238ad2f/resolv.conf","HostnamePath": "/var/lib/docker/containers/dee355965bca29c9355a5e9bff5132f89337b59b4e30c2459e89b6f64238ad2f/hostname","HostsPath": "/var/lib/docker/containers/dee355965bca29c9355a5e9bff5132f89337b59b4e30c2459e89b6f64238ad2f/hosts","LogPath": "/var/lib/docker/containers/dee355965bca29c9355a5e9bff5132f89337b59b4e30c2459e89b6f64238ad2f/dee355965bca29c9355a5e9bff5132f89337b59b4e30c2459e89b6f64238ad2f-json.log","Name": "/centosTest","RestartCount": 0,"Driver": "overlay2","Platform": "linux","MountLabel": "","ProcessLabel": "","AppArmorProfile": "","ExecIDs": null,"HostConfig": {"Binds": null,"ContainerIDFile": "","LogConfig": {"Type": "json-file","Config": {}},"NetworkMode": "default","PortBindings": {},"RestartPolicy": {"Name": "no","MaximumRetryCount": 0},"AutoRemove": false,"VolumeDriver": "","VolumesFrom": null,"ConsoleSize": [50,180],"CapAdd": null,"CapDrop": null,"CgroupnsMode": "host","Dns": [],"DnsOptions": [],"DnsSearch": [],"ExtraHosts": null,"GroupAdd": null,"IpcMode": "private","Cgroup": "","Links": null,"OomScoreAdj": 0,"PidMode": "","Privileged": false,"PublishAllPorts": false,"ReadonlyRootfs": false,"SecurityOpt": null,"UTSMode": "","UsernsMode": "","ShmSize": 67108864,"Runtime": "runc","Isolation": "","CpuShares": 0,"Memory": 0,"NanoCpus": 0,"CgroupParent": "","BlkioWeight": 0,"BlkioWeightDevice": [],"BlkioDeviceReadBps": [],"BlkioDeviceWriteBps": [],"BlkioDeviceReadIOps": [],"BlkioDeviceWriteIOps": [],"CpuPeriod": 0,"CpuQuota": 0,"CpuRealtimePeriod": 0,"CpuRealtimeRuntime": 0,"CpusetCpus": "","CpusetMems": "","Devices": [],"DeviceCgroupRules": null,"DeviceRequests": null,"MemoryReservation": 0,"MemorySwap": 0,"MemorySwappiness": null,"OomKillDisable": false,"PidsLimit": null,"Ulimits": null,"CpuCount": 0,"CpuPercent": 0,"IOMaximumIOps": 0,"IOMaximumBandwidth": 0,"MaskedPaths": ["/proc/asound","/proc/acpi","/proc/kcore","/proc/keys","/proc/latency_stats","/proc/timer_list","/proc/timer_stats","/proc/sched_debug","/proc/scsi","/sys/firmware"],"ReadonlyPaths": ["/proc/bus","/proc/fs","/proc/irq","/proc/sys","/proc/sysrq-trigger"]},"GraphDriver": {"Data": {"LowerDir": "/var/lib/docker/overlay2/6b5f1d67ac77a57910dbe442356bec38416d3fa9f355c9810a04de8a0032c20a-init/diff:/var/lib/docker/overlay2/0351cac31df5ec6bd716f7dd314842417100097dcad45cdbf3b2b602df85ac0d/diff","MergedDir": "/var/lib/docker/overlay2/6b5f1d67ac77a57910dbe442356bec38416d3fa9f355c9810a04de8a0032c20a/merged","UpperDir": "/var/lib/docker/overlay2/6b5f1d67ac77a57910dbe442356bec38416d3fa9f355c9810a04de8a0032c20a/diff","WorkDir": "/var/lib/docker/overlay2/6b5f1d67ac77a57910dbe442356bec38416d3fa9f355c9810a04de8a0032c20a/work"},"Name": "overlay2"},"Mounts": [{"Type": "volume","Name": "75d6a87411d050df05a6a6b9179ff9abbd89afc34641ce7bbf435d6671172565","Source": "/var/lib/docker/volumes/75d6a87411d050df05a6a6b9179ff9abbd89afc34641ce7bbf435d6671172565/_data","Destination": "/opt/data","Driver": "local","Mode": "","RW": true,"Propagation": ""}],"Config": {"Hostname": "dee355965bca","Domainname": "","User": "","AttachStdin": true,"AttachStdout": true,"AttachStderr": true,"Tty": true,"OpenStdin": true,"StdinOnce": true,"Env": ["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"],"Cmd": ["/bin/bash"],"Image": "centos","Volumes": {"/opt/data": {}},"WorkingDir": "","Entrypoint": null,"OnBuild": null,"Labels": {"org.label-schema.build-date": "20210915","org.label-schema.license": "GPLv2","org.label-schema.name": "CentOS Base Image","org.label-schema.schema-version": "1.0","org.label-schema.vendor": "CentOS"}},"NetworkSettings": {"Bridge": "","SandboxID": "f35da6a5c2575f9ed03c6474b59c0358c9b3944ce5f0fb6b20655df61a2dc185","HairpinMode": false,"LinkLocalIPv6Address": "","LinkLocalIPv6PrefixLen": 0,"Ports": {},"SandboxKey": "/var/run/docker/netns/f35da6a5c257","SecondaryIPAddresses": null,"SecondaryIPv6Addresses": null,"EndpointID": "ba7973b2a91ca6dc3e75351903537ecd4158116edfc2871a2c94a8d77a19cc95","Gateway": "172.17.0.1","GlobalIPv6Address": "","GlobalIPv6PrefixLen": 0,"IPAddress": "172.17.0.2","IPPrefixLen": 16,"IPv6Gateway": "","MacAddress": "02:42:ac:11:00:02","Networks": {"bridge": {"IPAMConfig": null,"Links": null,"Aliases": null,"NetworkID": "348aaaac8b83d35b8f2b750e66eefa696566a774d5791710e2b15e0e3d101332","EndpointID": "ba7973b2a91ca6dc3e75351903537ecd4158116edfc2871a2c94a8d77a19cc95","Gateway": "172.17.0.1","IPAddress": "172.17.0.2","IPPrefixLen": 16,"IPv6Gateway": "","GlobalIPv6Address": "","GlobalIPv6PrefixLen": 0,"MacAddress": "02:42:ac:11:00:02","DriverOpts": null}}}}
]

里面的 Mounts 部分 是挂载的意思：

然后查看对应的宿主机位置：

ls /var/lib/docker/volumes/75d6a87411d050df05a6a6b9179ff9abbd89afc34641ce7bbf435d6671172565/_data

这里确实看到了之前创建的文件。

然后进入宿主机目录下新增文件，看容器内部是否会出现同样的文件：

转到容器终端窗口：

同样产生了 456文件。两边是互通的。

方法2

命令：

docker run -it --name centosTest2 -v /opt/data:/data centos /bin/bash

这种方式对于容器来说是一样的，对于宿主机来说，多出了如下目录：

需要修改主机目录时，可以使用该命令。

3、volumes-from 案例

引用数据卷命令：

docker run -it --name cen1 --volumes-from centosTest centos

4、备份/恢复数据卷

备份：

docker run --rm --volumes-from data -v $(pwd):/backup centos tar cvf /backup/data.tar /opt/data

恢复：

docker run --rm --volumes-from data -v $(pwd):/backup centos tar xvf /backup/data.tar -C /

释义：
docker run --rm ----- 启动一个新的容器，执行完毕删除
–volumes-from data ------- data容器中挂载卷
-v $(pwd):/backup --------挂载当前目录到容器中为backup
cvf /backup/data.tar /opt/data --------- 备份/opt/data目录（即卷中所有的数据）为data.tar

xvf /backup/data.tar -C / ---------- 解压data.tar 到根目录/ ，因tar归档中已包含了/opt/data路径

5、删除数据卷

docker rm -v data