本文中涉及的源码、测试环境都是基于docker 0.11.1版本系统和docker-registry 0.6.5版本系统。
docker在主机上默认的文件保存位置为/var/lib/docker
drwxr-xr-x 2 root root 4096 May 20 11:13 apparmor/
drwxr-xr-x 5 root root 4096 Jan 19 09:28 aufs/
drwx------ 140 root root 20480 May 16 16:44 containers/
drwx------ 3 root root 4096 Jan 19 09:28 execdriver/
drwx------ 186 root root 20480 May 16 11:39 graph/
drwx------ 2 root root 4096 May 16 15:47 init/
-rw-r--r-- 1 root root 52224 May 16 16:44 linkgraph.db
-rw------- 1 root root 4720 May 16 11:44 repositories-aufs
drwx------ 3 root root 4096 Apr 29 16:50 vfs/
drwx------ 100 root root 12288 May 9 12:49 volumes/
aufs目录中有三个目录，diff、layers、mnt。
diff中保存着每个镜像的layer文件解压后的结果。
layers中保存每个镜像的继承关系。
mnt目录中保存容器运行的rootfs。
containers目录中保存每个容器的配置文件、环境变量文件以及日志文件。
以下是containers目录中一个容器目录中的文件内容。
drwx------ 2 root root 4096 May 16 16:58 ./
drwx------ 140 root root 20480 May 16 16:44 ../
-rw------- 1 root root 4567 May 16 15:48 84d63434aaf9d94bce248b88743a20d7b8d55b55cc7e7643b68cc6f9e8257e02-json.log
-rw-r--r-- 1 root root 102 May 14 15:21 config.env
-rw-r--r-- 1 root root 1557 May 16 15:47 config.json
-rw-r--r-- 1 root root 291 May 16 15:47 hostconfig.json
-rw-r--r-- 1 root root 13 May 16 15:47 hostname
-rw-r--r-- 1 root root 174 May 16 15:47 hosts
-rw-r--r-- 1 root root 20 May 14 15:21 resolv.conf
退出一个容器后，容器的目录仍然保留。只有通过docker rm 命令删除容器后，containers目录中相应容器的目录才会被删除。
运行中的容器会在execdriver/native下有一个相应的目录，包含container.json、pid、start三个文件。
container.json是容器的描述文件。
{
"hostname":"84d63434aaf9",
"environment":[
"HOME=/","PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"HOSTNAME=84d63434aaf9"
],
"namespaces":{
"NEWIPC":true,
"NEWNET":true,
"NEWNS":true,
"NEWPID":true,
"NEWUTS":true
},
"capabilities_mask":{
"AUDIT_CONTROL":false,
"AUDIT_WRITE":false,
"MAC_ADMIN":false,
"MAC_OVERRIDE":false,
"MKNOD":true,
"NET_ADMIN":false,
"SETPCAP":false,
"SYSLOG":false,
"SYS_ADMIN":false,
"SYS_MODULE":false,
"SYS_NICE":false,
"SYS_PACCT":false,
"SYS_RAWIO":false,
"SYS_RESOURCE":false,
"SYS_TIME":false,
"SYS_TTY_CONFIG":false
},
"networks":[
{
"type":"loopback",
"address":"127.0.0.1/0",
"gateway":"localhost",
"mtu":1500
},
{
"type":"veth",
"context":{"bridge":"docker0","prefix":"veth"},
"address":"172.17.0.3/16",
"gateway":"172.17.42.1",
"mtu":1500}
],
"cgroups":{"name":"84d63434aaf9d94bce248b88743a20d7b8d55b55cc7e7643b68cc6f9e8257e02","parent":"docker"},
"context":{
"apparmor_profile":"docker-default",
"mount_label":"",
"process_label":"",
"restrictions":"true"
},
"mounts":[
{"type":"devtmpfs"},
{"type":"bind","source":"/var/lib/docker/init/dockerinit-0.11.1","destination":"/.dockerinit","private":true},
{"type":"bind","source":"/var/lib/docker/containers/84d63434aaf9d94bce248b88743a20d7b8d55b55cc7e7643b68cc6f9e8257e02/resolv.conf","destination":"/etc/resolv.conf","private":true},
{"type":"bind","source":"/var/lib/docker/containers/84d63434aaf9d94bce248b88743a20d7b8d55b55cc7e7643b68cc6f9e8257e02/hostname","destination":"/etc/hostname","private":true},
{"type":"bind","source":"/var/lib/docker/containers/84d63434aaf9d94bce248b88743a20d7b8d55b55cc7e7643b68cc6f9e8257e02/hosts","destination":"/etc/hosts","private":true}
]
pid文件中保存着容器的第一个进程id。
start文件中的内容尚不清楚，需要后续通过阅读代码来确定。
graph目录保存镜像信息，每个镜像有两个描述文件。
json文件保存镜像描述
{
"id":"8aedcdadf14bb95a53f712aace7d0cb657447d24e41831518392d1a2b05d8bf7",
"parent":"99ec81b80c55d906afd8179560fdab0ee93e32c52053816ca1d531597c1ff48f",
"created":"2014-05-15T02:37:51.21802123Z",
"container":"1d4f82ac317735ab5d51853fc5d61346351b79fb41e9e961172e45f0dba31e75",
"container_config":{
"Hostname":"1d4f82ac3177",
"Domainname":"",
"User":"",
"Memory":0,
"MemorySwap":0,
"CpuShares":0,
"AttachStdin":true,
"AttachStdout":true,
"AttachStderr":true,
"PortSpecs":null,
"ExposedPorts":null,
"Tty":true,
"OpenStdin":true,
"StdinOnce":true,
"Env":[
"HOME=/",
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd":["/bin/bash"],
"Image":"99ec81b80c55",
"Volumes":null,
"WorkingDir":"",
"Entrypoint":null,
"NetworkDisabled":false,
"OnBuild":null
},
"docker_version":"0.10.0",
"config":{
"Hostname":"",
"Domainname":"",
"User":"",
"Memory":0,
"MemorySwap":0,
"CpuShares":0,
"AttachStdin":false,
"AttachStdout":false,
"AttachStderr":false,
"PortSpecs":null,
"ExposedPorts":null,
"Tty":true,
"OpenStdin":true,
"StdinOnce":true,
"Env":[
"HOME=/",
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd":["/bin/bash"],
"Image":"",
"Volumes":null,
"WorkingDir":"",
"Entrypoint":null,
"NetworkDisabled":false,
"OnBuild":null},
"architecture":"amd64",
"os":"linux",
"Size":43197746}
layersize文件保存镜像大小
init目标保存各个版本docker的初始化程序
linkgraph.db是一个sqlite3数据库文件，里面有两个表edge和entity。用于记录容器的链接关系。
sqlite> .schema
CREATE TABLE entity (
id text NOT NULL PRIMARY KEY
);
CREATE TABLE edge (
"entity_id" text NOT NULL,
"parent_id" text NULL,
"name" text NOT NULL,
CONSTRAINT "parent_fk" FOREIGN KEY ("parent_id") REFERENCES "entity" ("id"),
CONSTRAINT "entity_fk" FOREIGN KEY ("entity_id") REFERENCES "entity" ("id")
);
CREATE UNIQUE INDEX "name_parent_ix" ON "edge" (parent_id, name);
repositories-aufs记录docker中的镜像信息。
{
"Repositories":{
"10.1.1.64:5000/ubuntu":{
"12.10":"f030997216f3f605c3db2e60fac9a327910f30319b3fae95a457f87801bc2734",
"13.04":"514b348987eff7991ad24b3fa26838f9768f41a618a1f78c8a4e6d5382b14df9",
"13.10":"7c0d7c261905a9fe83d1aea4037a265058f47e1e3e1134daac879393741cc016",
"14.04":"8aedcdadf14bb95a53f712aace7d0cb657447d24e41831518392d1a2b05d8bf7",
"latest":"8aedcdadf14bb95a53f712aace7d0cb657447d24e41831518392d1a2b05d8bf7",
"quantal":"f030997216f3f605c3db2e60fac9a327910f30319b3fae95a457f87801bc2734",
"raring":"514b348987eff7991ad24b3fa26838f9768f41a618a1f78c8a4e6d5382b14df9",
"saucy":"7c0d7c261905a9fe83d1aea4037a265058f47e1e3e1134daac879393741cc016",
"trusty":"8aedcdadf14bb95a53f712aace7d0cb657447d24e41831518392d1a2b05d8bf7"
}
}
}
此目录作用暂时不清楚。