[转]关于docker包存储结构说明

原文：http://blog.csdn.net/w412692660/article/details/49005631

前段时间与同事交流docker的安装包层次结构,并沟通相关每个文件的作用,但是一直没有进行文字备份,过去已经一月有余,还是将其记录下来,供后续工作参考

默认docker启动会将目录安装在/var/lib/docker中,不过建议可以修改 --graph="/path/docker"安装目录.

防止系统盘空间占用过大,最好选择存储空间较大的分区.

docker目录:

containers 当前容器的集合(相当于docker ps -a)

目录是容器的配置信息及当前状态.

常用的包括容器配置信息, 网络信息,日志,都是来源于此,默认存储方式json

我们平时使用的docker inspect , docker logs, docker ps 都是来自于文件夹

一般用于docker容器重启时,恢复配置使用的依据,由于挂起方式是基础环境,没有办法像VM软件的挂起可以冻结进程,也是docker类似半虚拟容器很难实现真正的将运行容器进行分发,故此如果想实现有状态的运行容器漂移是仍是十分困难.

hostname 主机名称

hosts 容器重启

resolv.conf是DNS服务,默认是拷贝/etc/resolv.conf的配置

hostconfig.json是核心配置之一, 包括网络, CPU, MEM等,dockerrun选项配置形成的容器设置都可以在此处查询到.

config.json是核心docker状态管理文件, 由她加载上述所有文件

config.json 是核心docker状态管理文件, 由她加载上述所有文件

[plain] view plain copy

{

"State": {

"Running": false,

"Paused": false,

"Restarting": false,

"OOMKilled": false,

"Dead": false,

"Pid": 0,

"ExitCode": 0,

"Error": "",

"StartedAt": "2015-10-10T07:36:31.250795069Z",

"FinishedAt": "2015-10-10T07:37:09.587772608Z"

},

"ID": "02bbc65a5c2a285c34565fd9b0b3b485772faaf968a2f2eb3df1fff649119def",

"Created": "2015-10-10T07:36:30.400677786Z",

"Path": "/bin/bash",

"Args": [],

"Config": {

"Hostname": "02bbc65a5c2a",

"Domainname": "",

"User": "",

"AttachStdin": true,

"AttachStdout": true,

"AttachStderr": true,

"PortSpecs": null,

"ExposedPorts": null,

"Tty": true,

"OpenStdin": true,

"StdinOnce": true,

"Env": null,

"Cmd": [

"/bin/bash"

],

"Image": "docker.io/coreos/apache",

"Volumes": {

"/data0": {}

},

"VolumeDriver": "",

"WorkingDir": "",

"Entrypoint": null,

"NetworkDisabled": false,

"MacAddress": "",

"OnBuild": null,

"Labels": {}

},

"Image": "87026dcb00443eb7f1725b1c9f4fb8210027a19364103854a1e5f606b95019ff",

"NetworkSettings": {

"Bridge": "",

"EndpointID": "",

"Gateway": "",

"GlobalIPv6Address": "",

"GlobalIPv6PrefixLen": 0,

"HairpinMode": false,

"IPAddress": "",

"IPPrefixLen": 0,

"IPv6Gateway": "",

"LinkLocalIPv6Address": "",

"LinkLocalIPv6PrefixLen": 0,

"MacAddress": "",

"NetworkID": "",

"PortMapping": null,

"Ports": null,

"SandboxKey": "",

"SecondaryIPAddresses": null,

"SecondaryIPv6Addresses": null

},

"ResolvConfPath": "/var/lib/docker/containers/02bbc65a5c2a285c34565fd9b0b3b485772faaf968a2f2eb3df1fff649119def/resolv.conf",

"HostnamePath": "/var/lib/docker/containers/02bbc65a5c2a285c34565fd9b0b3b485772faaf968a2f2eb3df1fff649119def/hostname",

"HostsPath": "/var/lib/docker/containers/02bbc65a5c2a285c34565fd9b0b3b485772faaf968a2f2eb3df1fff649119def/hosts",

"LogPath": "/var/lib/docker/containers/02bbc65a5c2a285c34565fd9b0b3b485772faaf968a2f2eb3df1fff649119def/02bbc65a5c2a285c34565fd9b0b3b485772faaf968a2f2eb3df1fff649119def-json.log",

"Name": "/determined_poincare",

"Driver": "devicemapper",

"ExecDriver": "native-0.2",

"MountLabel": "",

"ProcessLabel": "",

"RestartCount": 0,

"UpdateDns": false,

"MountPoints": {

"/data0": {

"Name": "53938b2752dc6f84475657a57ce87d45a329d3815426c1f0988c18b6bbf2df86",

"Destination": "/data0",

"Driver": "local",

"RW": true,

"Source": "",

"Relabel": ""

}

},

"Volumes": {},

"VolumesRW": {},

"AppArmorProfile": ""

}

XXX.log 是容器log日志,也仅有启动容器时,运行命令的日志,其他如后台程序的日志并不在此日志中.

devicemapper 是以ID为标识存储镜像和容器,可以说devicemapper是最核心的部分,同时也是最容易存储超标的部分,其是lvm的软件之docker主要用了他的快照功能,完成image的思想基石,containers和image的json文件都是描述,真正存储数据的则是devicemapper/data.

其中包括临时容器和镜像文件, 尽管我们是容器内部的文件拷贝,也会促使data文件的增大,后续打算找个专题来解释他吧,docker的封装devicemapper的API是很不错,有兴趣可以参考/github.com/docker/docker/daemon/graphdriver/devmapper/driver.go , 仅仅对外暴漏数个接口,具体实现deviceset.go中.

graph 存储镜像信息,使用json方式存储描述,真正数据也是存储在devicemapper中,镜像ID则是devicemapper存储的ID.

devicemapper , 具体可参考:graph.go的Register(img*image.Image,layerDataio.Reader)函数

镜像内容包括:镜像ID,父镜像ID,父镜像的容器,另每个镜像都有一个初始镜像,可以追溯

[java] view plain copy

// Create creates a new image and registers it in the graph.

// 创建一个新的镜像

func (graph *Graph) Create(layerData io.Reader, containerID, containerImage, comment, author string, containerConfig, config *runconfig.Config) (*image.Image, error) {

// 初始化镜像实例

img := &image.Image{

ID: stringid.GenerateRandomID(), // 生成镜像ID

Comment: comment, // 命令

Created: time.Now().UTC(), // 时间

DockerVersion: dockerversion.VERSION, // docker版本

Author: author, // 作者

Config: config, // 相关container配置, 请查看graph/**/json

Architecture: runtime.GOARCH,

OS: runtime.GOOS,

}

// 非初始镜像,则设置镜像父子关系

if containerID != "" {

img.Parent = containerImage

img.Container = containerID

img.ContainerConfig = *containerConfig

}

// 注册镜像

if err := graph.Register(img, layerData); err != nil {

return nil, err

}

return img, nil

}

vfs 是我们使用不定向挂载时引用,比如说我们-v /data0 ,则默认使用vfs做为挂载路径,使用dockerfile时较为常用

volumes 是挂载使用的映射关系,对应挂载源与挂载路径的关系,同时拥有ID,用于可以多个容器使用一个挂在源

linkgraph.db 是graph存储镜像之间的关联关系,是初始化graph对象的依据.同时,graph文件夹的信息与linkgraph.db是数据重合的.