Docker系列——容器数据卷

于 2020-10-26 23:31:10 发布
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分类专栏： Docker实战 文章标签： linux docker
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本文链接：https://blog.youkuaiyun.com/Lambert_shikui/article/details/109300863
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Docker系列——容器数据卷

前言

使用Dockerfile构建一个挂载了数据卷的镜像

在了解容器数据卷之前我们需要做一些准备工作。
之前我们创建数据卷的是在启动容器的时候，命令如下

docker run -it -v /宿主机路径:/容器路径 镜像名称

现在我们使用DockerFile来构建一个挂载了数据卷的镜像。

  • 首先我们简单的理解以下DockerFile是什么?
    DockerFile：是镜像的构建文件。可以这样理解，我们是用.java文件编译成.class文件，这个镜像就相当于.class文件，DockerFile就是.java文件。

我们宿主机中已经有了Centos镜像

[root@localhost /]# cd /
[root@localhost /]# mkdir myDocker
[root@localhost /]# cd myDocker/
[root@localhost myDocker]# vim Dockerfile
[root@localhost myDocker]# cat Dockerfile 
FROM centos
VOLUME ["/dataVolumeContainer01","/dataVolumeContainer02"]
CMD echo "finished..."
CMD /bin/bash
[root@localhost myDocker]# docker build -f /myDocker/Dockerfile -t foustar/centos .
Sending build context to Docker daemon 2.048 kB
Step 1/4 : FROM centos
 ---> 0d120b6ccaa8
Step 2/4 : VOLUME /dataVolumeContainer01 /dataVolumeContainer02
 ---> Running in 1080bc4f8b51
 ---> c8f2803dd45e
Removing intermediate container 1080bc4f8b51
Step 3/4 : CMD echo "finished..."
 ---> Running in 055981ee3f0c
 ---> aafb7fa60c83
Removing intermediate container 055981ee3f0c
Step 4/4 : CMD /bin/bash
 ---> Running in df4ada4e7c4a
 ---> 1e7a5c077958
Removing intermediate container df4ada4e7c4a
Successfully built 1e7a5c077958
[root@localhost myDocker]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
foustar/centos      latest              1e7a5c077958        4 seconds ago       215 MB
docker.io/centos    latest              0d120b6ccaa8        2 months ago        215 MB

此时我们使用Dockerfile构建了一个挂载了数据卷的镜像，就是每次启动就默认挂载了"/dataVolumeContainer01","/dataVolumeContainer02"。挂载的宿主机的位置会有一个默认路径，可以使用inspect进行查看，下面我们来测试以下，镜像是否成功。

[root@localhost myDocker]# docker run -it --name test foustar/centos
[root@ee7775590430 /]# ls
bin  dataVolumeContainer01  dataVolumeContainer02  dev	etc  home  lib	lib64  lost+found  media  mnt  opt  proc  root	run  sbin  srv	sys  tmp  usr  var
[root@ee7775590430 /]# cd dataVolumeContainer01
[root@ee7775590430 dataVolumeContainer01]# ls
[root@ee7775590430 dataVolumeContainer01]# touch 1.txt
[root@ee7775590430 dataVolumeContainer01]# ls
1.txt
[root@ee7775590430 dataVolumeContainer01]# 您在 /var/mail/root 中有新邮件

[root@localhost myDocker]# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
ee7775590430        foustar/centos      "/bin/sh -c /bin/bash"   3 minutes ago       Up 3 minutes                            test
[root@localhost myDocker]# docker inspect ee7775590430
[
    {
        "Id": "ee7775590430363f13fd060a416083375a627996ccd81e121cb970c7ef627106",
        "Created": "2020-10-26T15:17:43.083584734Z",
        "Path": "/bin/sh",
        "Args": [
            "-c",
            "/bin/bash"
        ],
        "State": {
            "Status": "running",
            "Running": true,
            "Paused": false,
            "Restarting": false,
            "OOMKilled": false,
            "Dead": false,
            "Pid": 22232,
            "ExitCode": 0,
            "Error": "",
            "StartedAt": "2020-10-26T15:17:44.109896486Z",
            "FinishedAt": "0001-01-01T00:00:00Z"
        },
        "Image": "sha256:1e7a5c0779589e7bddedd7bb227c482b1256b300047c9762a2a8da9d8cca8b9e",
        "ResolvConfPath": "/var/lib/docker/containers/ee7775590430363f13fd060a416083375a627996ccd81e121cb970c7ef627106/resolv.conf",
        "HostnamePath": "/var/lib/docker/containers/ee7775590430363f13fd060a416083375a627996ccd81e121cb970c7ef627106/hostname",
        "HostsPath": "/var/lib/docker/containers/ee7775590430363f13fd060a416083375a627996ccd81e121cb970c7ef627106/hosts",
        "LogPath": "",
        "Name": "/test",
        "RestartCount": 0,
        "Driver": "devicemapper",
        "MountLabel": "system_u:object_r:svirt_sandbox_file_t:s0:c120,c1019",
        "ProcessLabel": "system_u:system_r:svirt_lxc_net_t:s0:c120,c1019",
        "AppArmorProfile": "",
        "ExecIDs": null,
        "HostConfig": {
            "Binds": null,
            "ContainerIDFile": "",
            "LogConfig": {
                "Type": "journald",
                "Config": {}
            },
            "NetworkMode": "default",
            "PortBindings": {},
            "RestartPolicy": {
                "Name": "no",
                "MaximumRetryCount": 0
            },
            "AutoRemove": false,
            "VolumeDriver": "",
            "VolumesFrom": null,
            "CapAdd": null,
            "CapDrop": null,
            "Dns": [],
            "DnsOptions": [],
            "DnsSearch": [],
            "ExtraHosts": null,
            "GroupAdd": null,
            "IpcMode": "",
            "Cgroup": "",
            "Links": null,
            "OomScoreAdj": 0,
            "PidMode": "",
            "Privileged": false,
            "PublishAllPorts": false,
            "ReadonlyRootfs": false,
            "SecurityOpt": null,
            "UTSMode": "",
            "UsernsMode": "",
            "ShmSize": 67108864,
            "Runtime": "docker-runc",
            "ConsoleSize": [
                0,
                0
            ],
            "Isolation": "",
            "CpuShares": 0,
            "Memory": 0,
            "NanoCpus": 0,
            "CgroupParent": "",
            "BlkioWeight": 0,
            "BlkioWeightDevice": null,
            "BlkioDeviceReadBps": null,
            "BlkioDeviceWriteBps": null,
            "BlkioDeviceReadIOps": null,
            "BlkioDeviceWriteIOps": null,
            "CpuPeriod": 0,
            "CpuQuota": 0,
            "CpuRealtimePeriod": 0,
            "CpuRealtimeRuntime": 0,
            "CpusetCpus": "",
            "CpusetMems": "",
            "Devices": [],
            "DiskQuota": 0,
            "KernelMemory": 0,
            "MemoryReservation": 0,
            "MemorySwap": 0,
            "MemorySwappiness": -1,
            "OomKillDisable": false,
            "PidsLimit": 0,
            "Ulimits": null,
            "CpuCount": 0,
            "CpuPercent": 0,
            "IOMaximumIOps": 0,
            "IOMaximumBandwidth": 0
        },
        "GraphDriver": {
            "Name": "devicemapper",
            "Data": {
                "DeviceId": "49",
                "DeviceName": "docker-253:1-69090742-c111e7d9ab79841427f8a9a41ffb9f7a524d589153360222032f1c9794a7f6fc",
                "DeviceSize": "10737418240"
            }
        },
        "Mounts": [
            {
                "Type": "volume",
                "Name": "10fc20ad114a261d0893edd87e475e4505507a907a2f9f1062814b8597f79012",
                "Source": "/var/lib/docker/volumes/10fc20ad114a261d0893edd87e475e4505507a907a2f9f1062814b8597f79012/_data",
                "Destination": "/dataVolumeContainer01",
                "Driver": "local",
                "Mode": "",
                "RW": true,
                "Propagation": ""
            },
            {
                "Type": "volume",
                "Name": "fef540f7f3d6dd624b0aeb8f3204064822aa10995b7b1b709bbeb910fd741631",
                "Source": "/var/lib/docker/volumes/fef540f7f3d6dd624b0aeb8f3204064822aa10995b7b1b709bbeb910fd741631/_data",
                "Destination": "/dataVolumeContainer02",
                "Driver": "local",
                "Mode": "",
                "RW": true,
                "Propagation": ""
            }
        ],
        "Config": {
            "Hostname": "ee7775590430",
            "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/sh",
                "-c",
                "/bin/bash"
            ],
            "ArgsEscaped": true,
            "Image": "foustar/centos",
            "Volumes": {
                "/dataVolumeContainer01": {},
                "/dataVolumeContainer02": {}
            },
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {
                "org.label-schema.build-date": "20200809",
                "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": "420f6f7db4b759b92b9c058061edafad4d83c56410bd619e5500b356e049738b",
            "HairpinMode": false,
            "LinkLocalIPv6Address": "",
            "LinkLocalIPv6PrefixLen": 0,
            "Ports": {},
            "SandboxKey": "/var/run/docker/netns/420f6f7db4b7",
            "SecondaryIPAddresses": null,
            "SecondaryIPv6Addresses": null,
            "EndpointID": "d7e54f2cb27393a021369c195ecd16600cb90d694bf47c90e2caf4684c476109",
            "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": "504bc5c7cc698404f89cea1e25b218d55b0c45b6e1e59e457f1d7a91c2f254d3",
                    "EndpointID": "d7e54f2cb27393a021369c195ecd16600cb90d694bf47c90e2caf4684c476109",
                    "Gateway": "172.17.0.1",
                    "IPAddress": "172.17.0.2",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "MacAddress": "02:42:ac:11:00:02"
                }
            }
        }
    }
]
您在 /var/mail/root 中有新邮件
[root@localhost myDocker]# cd /var/lib/docker/volumes/10fc20ad114a261d0893edd87e475e4505507a907a2f9f1062814b8597f79012/_data
[root@localhost _data]# ll
总用量 0
-rw-r--r--. 1 root root 0 10月 26 23:18 1.txt

从上面我们可以得知我们制作的这个镜像成功了。

容器数据卷是什么？

命名的容器挂载数据卷，其他容器通过挂载这个（父容器）实现数据共享，挂载数据卷的容器，称之为数据卷容器

案例实战

我们基于之前构建的镜像作为基础，来讲解这个容器数据卷，先删除无关的容器。
在这里插入图片描述

总结

容器之前的数据共享，容器卷的生命周期一直持续到没有容器使用它为止。

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