如何检查具有特定标记的Docker镜像是否存在于本地？

Question

我想知道本地是否存在具有特定标记的Docker镜像.如果Docker客户端本身不能这样做,我可以使用bash脚本.

只是为潜在的bash脚本提供一些提示,运行该docker images命令的结果将返回以下内容:

REPOSITORY                               TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
rabbitmq                                 latest              e8e654c05c91        5 weeks ago         143.5 MB
busybox                                  latest              8c2e06607696        6 weeks ago         2.433 MB
rabbitmq                                 3.4.4               a4fbaad9f996        11 weeks ago        131.5 MB

Answer 1

我经常测试结果docker images -q(如在这个脚本中):

if [[ "$(docker images -q myimage:mytag 2> /dev/null)" == "" ]]; then
  # do something
fi

但 因为docker images只REPOSITORY作为参数,你需要grep on tag,而不使用-q.

docker images 现在拿标签(docker 1.8+) [REPOSITORY[:TAG]]

下面提到的另一种方法是使用docker inspect.
但是对于docker 17+,图像的语法是:( docker image inspect在不存在的图像上,退出状态将为非0)

Answer 2

试试docker inspect,例如:

$ docker inspect --type=image treeder/hello.rb:nada
Error: No such image: treeder/hello.rb:nada
[]

但是现在有了一个存在的图像,你会得到一堆信息,例如:

$ docker inspect --type=image treeder/hello.rb:latest
[
{
    "Id": "85c5116a2835521de2c52f10ab5dda0ff002a4a12aa476c141aace9bc67f43ad",
    "Parent": "ecf63f5eb5e89e5974875da3998d72abc0d3d0e4ae2354887fffba037b356ad5",
    "Comment": "",
    "Created": "2015-09-23T22:06:38.86684783Z",
    ...
}
]

它是一个很好的json格式.

Answer 3

tldr:

docker image inspect myimage:mytag

通过示范......

成功,找到图片:

$ docker image pull busybox:latest
latest: Pulling from library/busybox
Digest: sha256:32f093055929dbc23dec4d03e09dfe971f5973a9ca5cf059cbfb644c206aa83f
Status: Image is up to date for busybox:latest

$ docker image inspect busybox:latest >/dev/null 2>&1 && echo yes || echo no
yes

失败,缺少图像:

$ docker image rm busybox:latest
Untagged: busybox:latest
Untagged: busybox@sha256:32f093055929dbc23dec4d03e09dfe971f5973a9ca5cf059cbfb644c206aa83f

$ docker image inspect busybox:latest >/dev/null 2>&1 && echo yes || echo no
no

参考:

https://docs.docker.com/engine/reference/commandline/image_inspect/

Answer 4

你可以使用如下:

[ ! -z $(docker images -q someimage:sometag) ] || echo "does not exist"

要么:

[ -z $(docker images -q someimage:sometag) ] || echo "already exists"