閱讀James Coyle's blog後,我發現docker save
和docker load
命令是我所需要的。
> docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
progrium/consul latest e9fe5db22401 11 days ago 25.81 MB
> docker save e9fe5db22401 | tar x
> ls e9fe5db22401*
VERSION json layer.tar
的VERSION
文件只包含1.0
,並且json
含有相當多的信息:
{
"id": "e9fe5db224015ddfa5ee9dbe43b414ecee1f3108fb6ed91add11d2f506beabff",
"parent": "68f9e4929a4152df9b79d0a44eeda042b5555fbd30a36f98ab425780c8d692eb",
"created": "2014-08-20T17:54:30.98176344Z",
"container": "3878e7e9b9935b7a1988cb3ebe9cd45150ea4b09768fc1af54e79b224bf35f26",
"container_config": {
"Hostname": "7f17ad58b5b8",
"Domainname": "",
"User": "",
"Memory": 0,
"MemorySwap": 0,
"CpuShares": 0,
"Cpuset": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"PortSpecs": null,
"ExposedPorts": {
"53/udp": {},
"8300/tcp": {},
"8301/tcp": {},
"8301/udp": {},
"8302/tcp": {},
"8302/udp": {},
"8400/tcp": {},
"8500/tcp": {}
},
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"HOME=/",
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"SHELL=/bin/bash"
],
"Cmd": [
"/bin/sh",
"-c",
"#(nop) CMD []"
],
"Image": "68f9e4929a4152df9b79d0a44eeda042b5555fbd30a36f98ab425780c8d692eb",
"Volumes": {
"/data": {}
},
"WorkingDir": "",
"Entrypoint": [
"/bin/start"
],
"NetworkDisabled": false,
"OnBuild": [
"ADD ./config /config/"
]
},
"docker_version": "1.1.2",
"author": "Jeff Lindsay <[email protected]>",
"config": {
"Hostname": "7f17ad58b5b8",
"Domainname": "",
"User": "",
"Memory": 0,
"MemorySwap": 0,
"CpuShares": 0,
"Cpuset": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"PortSpecs": null,
"ExposedPorts": {
"53/udp": {},
"8300/tcp": {},
"8301/tcp": {},
"8301/udp": {},
"8302/tcp": {},
"8302/udp": {},
"8400/tcp": {},
"8500/tcp": {}
},
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"HOME=/",
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"SHELL=/bin/bash"
],
"Cmd": [],
"Image": "68f9e4929a4152df9b79d0a44eeda042b5555fbd30a36f98ab425780c8d692eb",
"Volumes": {
"/data": {}
},
"WorkingDir": "",
"Entrypoint": [
"/bin/start"
],
"NetworkDisabled": false,
"OnBuild": [
"ADD ./config /config/"
]
},
"architecture": "amd64",
"os": "linux",
"Size": 0
}
的layer.tar
文件顯示爲空。所以檢查了父母和祖父母,他們都沒有在他們的layer.tar
文件中沒有文件。
所以假設4.0K是一個空的壓縮包的標準尺寸:
for layer in $(du -hs */layer.tar | grep -v 4.0K | cut -f2)
do (echo $layer:;tar tvf $layer)
done
地看到,這些包含在文件系統簡單的增量變化。
所以一個結論是,最好只使用Docker來構建映像並將其推送到註冊表中,就像Packer一樣。
從頭開始構建圖像的方法是described in the docs。原來docker import - scratch
並不關心tarball裏的內容。我只是假設這是rootfs。
> touch foo
> tar c foo | docker import - scratch
02bb6cd70aa2c9fbaba37c8031c7412272d804d50b2ec608e14db054fc0b9fab
> docker save 02bb6cd70aa2c9fbaba37c8031c7412272d804d50b2ec608e14db054fc0b9fab | tar x
> ls 02bb6cd70aa2c9fbaba37c8031c7412272d804d50b2ec608e14db054fc0b9fab/
VERSION json layer.tar
> tar tvf 02bb6cd70aa2c9fbaba37c8031c7412272d804d50b2ec608e14db054fc0b9fab/layer.tar
drwxr-xr-x 0/0 0 2014-09-01 13:46 ./
-rw-r--r-- 500/500 0 2014-09-01 13:46 foo
在OpenEmbedded的一體化方面,它可能是最好的打造rootfs
壓縮包,這是一件好事Yocto提供開箱即用,並使用official Python library導入根文件系統與import_image(src='rootfs.tar', repository='scratch')
壓縮包,然後將其推私有註冊表的方法。
這不是最優雅的解決方案,但這是它現在需要的工作方式。否則,人們可能會以自己的方式管理和部署rootfs
修訂版,並且只在目標主機上使用docker import
,這仍然不太合適,但有點簡單。