Docker - Docker Image及Image命令詳解

什么是鏡像（Image）

Docker鏡像（Docker Image）就是一個只讀的模板。比如，一個鏡像可以包含一個完整的Ubuntu操作系統環境。鏡像可以用來創建Docker容器。

在Docker的術語里，一個只讀層被稱為鏡像，一個鏡像是永遠不會變的。

由于Docker使用一個統一文件系統，Docker進程認為整個文件系統是以讀寫方式掛載的。 但是所有的變更都發生在頂層的可寫層，而下層的原始的只讀鏡像文件并未變化。由于鏡像不可寫，所以鏡像是無狀態的。

父鏡像

每一個鏡像都可能依賴于由一個或多個下層鏡像組成的另一個鏡像。我們有時說，下層那個鏡像是上層鏡像的父鏡像。而沒有任何父鏡像的鏡像，謂之基礎鏡像（Base Image）。

可以看一下這篇博客，會讓你對Docker的整體架構有一個很清晰的了解：Docker - 這應該就是你想要的Docker架構分析。

Docker Image Help

通過該命令可以查看Image下有哪些命令。

docker image help [root@izoq008ryseuupz ~]# docker image helpUsage: docker image COMMANDManage imagesCommands:build Build an image from a Dockerfilehistory Show the history of an imageimport Import the contents from a tarball to create a filesystem imageinspect Display detailed information on one or more imagesload Load an image from a tar archive or STDINls List imagesprune Remove unused imagespull Pull an image or a repository from a registrypush Push an image or a repository to a registryrm Remove one or more imagessave Save one or more images to a tar archive (streamed to STDOUT by default)tag Create a tag TARGET_IMAGE that refers to SOURCE_IMAGERun 'docker image COMMAND --help' for more information on a command.

通過docker image COMMAND --help來知道每一個Image命令的詳細信息。

Run 'docker image COMMAND --help' for more information on a command.

Docker Image LS

docker image ls --help [root@izoq008ryseuupz ~]# docker image ls --helpUsage: docker image ls [OPTIONS] [REPOSITORY[:TAG]]List imagesAliases:ls, images, listOptions:-a, --all Show all images (default hides intermediate images)--digests Show digests-f, --filter filter Filter output based on conditions provided--format string Pretty-print images using a Go template--no-trunc Don't truncate output-q, --quiet Only show numeric IDs

比如docker image ls -a，展示所有Image的關鍵信息。

[root@izoq008ryseuupz ~]# docker image ls -a REPOSITORY TAG IMAGE ID CREATED SIZE node latest 5377c9a2fb1f 5 weeks ago 943MB openzipkin/zipkin latest 1850194f377c 3 months ago 160MB rancher/server stable 98d8bb571885 6 months ago 1.08GB redis 5.0.7 7eed8df88d3b 8 months ago 98.2MB hello-world latest bf756fb1ae65 10 months ago 13.3kB

docker images、docker image ls和docker image ls -a是一樣的效果。

比如docker image ls -q，就只輸出Image的IMAGE ID 。

[root@izoq008ryseuupz ~]# docker image ls -q 5377c9a2fb1f 1850194f377c 98d8bb571885 7eed8df88d3b bf756fb1ae65

其他的命令選項可以自己試一試。

Docker Image Pull

拉取鏡像。

docker image pull --help [root@izoq008ryseuupz ~]# docker image pull --helpUsage: docker image pull [OPTIONS] NAME[:TAG|@DIGEST]Pull an image or a repository from a registryOptions:-a, --all-tags Download all tagged images in the repository--disable-content-trust Skip image verification (default true)--platform string Set platform if server is multi-platform capable-q, --quiet Suppress verbose output

拉取centos:7鏡像。

docker image pull centos:7 [root@izoq008ryseuupz ~]# docker image pull centos:7 7: Pulling from library/centos 2d473b07cdd5: Pull complete Digest: sha256:0f4ec88e21daf75124b8a9e5ca03c37a5e937e0e108a255d890492430789b60e Status: Downloaded newer image for centos:7 docker.io/library/centos:7

拉取centos:6鏡像，只想要輸出pull的簡要信息，不輸出pull的詳細信息，如Downloading的進度。

docker image pull -q centos:6 [root@izoq008ryseuupz ~]# docker image pull -q centos:6 docker.io/library/centos:6

其他的命令選項可以自己試一試。

Docker Image Prune

此命令會把所有未使用的鏡像進行刪除（Remove unused images），慎用！

docker image prune --help [root@izoq008ryseuupz ~]# docker image prune --helpUsage: docker image prune [OPTIONS]Remove unused imagesOptions:-a, --all Remove all unused images, not just dangling ones--filter filter Provide filter values (e.g. 'until=<timestamp>')-f, --force Do not prompt for confirmation docker image prune [root@izoq008ryseuupz ~]# docker image prune WARNING! This will remove all dangling images. Are you sure you want to continue? [y/N] y Total reclaimed space: 0B

Docker Image RM

刪除指定鏡像。

docker image rm --help [root@izoq008ryseuupz ~]# docker image rm --helpUsage: docker image rm [OPTIONS] IMAGE [IMAGE...]Remove one or more imagesAliases:rm, rmi, removeOptions:-f, --force Force removal of the image--no-prune Do not delete untagged parents

刪除centos:7。

docker image rm centos:7 [root@izoq008ryseuupz ~]# docker image rm centos:7 Untagged: centos:7 Untagged: centos@sha256:0f4ec88e21daf75124b8a9e5ca03c37a5e937e0e108a255d890492430789b60e Deleted: sha256:8652b9f0cb4c0599575e5a003f5906876e10c1ceb2ab9fe1786712dac14a50cf Deleted: sha256:174f5685490326fc0a1c0f5570b8663732189b327007e47ff13d2ca59673db02

強制刪除centos:6。

docker image rm -f centos:6 [root@izoq008ryseuupz ~]# docker image rm -f centos:6 Untagged: centos:6 Untagged: centos@sha256:dec8f471302de43f4cfcf82f56d99a5227b5ea1aa6d02fa56344986e1f4610e7 Deleted: sha256:d0957ffdf8a2ea8c8925903862b65a1b6850dbb019f88d45e927d3d5a3fa0c31 Deleted: sha256:af6bf1987c2eb07d73f33836b0d8fd825d7c785273526b077e46780e8b4b2ae9

其他的命令選項可以自己試一試。

Docker Image Tag

對原有鏡像打tag，會生成新鏡像。

docker image tag --help [root@izoq008ryseuupz ~]# docker image tag --helpUsage: docker image tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]Create a tag TARGET_IMAGE that refers to SOURCE_IMAGE docker image tag centos:6 centos:kaven.blog

Docker Image Save

保存鏡像。

docker image save --help [root@izoq008ryseuupz ~]# docker image save --helpUsage: docker image save [OPTIONS] IMAGE [IMAGE...]Save one or more images to a tar archive (streamed to STDOUT by default)Options:-o, --output string Write to a file, instead of STDOUT docker image save centos:kaven.blog > kaven.blog.tar [root@izoq008ryseuupz ~]# docker image save centos:kaven.blog > kaven.blog.tar #保存到當前目錄 [root@izoq008ryseuupz ~]# ls kaven* kaven.blog.tar docker image save centos:kaven.blog -o /usr/kaven.blog.tar [root@izoq008ryseuupz ~]# docker image save centos:kaven.blog -o /usr/kaven.blog.tar #保存到別的目錄 [root@izoq008ryseuupz ~]# ls /usr/kaven* /usr/kaven.blog.tar

Docker Image Load

加載鏡像。

docker image load --help [root@izoq008ryseuupz ~]# docker image load --helpUsage: docker image load [OPTIONS]Load an image from a tar archive or STDINOptions:-i, --input string Read from tar archive file, instead of STDIN-q, --quiet Suppress the load output docker image load < kaven.blog.tar [root@izoq008ryseuupz ~]# docker image rm centos:kaven.blog Untagged: centos:kaven.blog [root@izoq008ryseuupz ~]# docker image load < kaven.blog.tar Loaded image: centos:kaven.blog

docker image load -i /usr/kaven.blog.tar [root@izoq008ryseuupz ~]# docker image rm centos:kaven.blog Untagged: centos:kaven.blog [root@izoq008ryseuupz ~]# docker image load -i /usr/kaven.blog.tar Loaded image: centos:kaven.blog

其他的命令選項可以自己試一試。

Docker Image History

顯示鏡像的操作歷史。

docker image history --help [root@izoq008ryseuupz ~]# docker image history --helpUsage: docker image history [OPTIONS] IMAGEShow the history of an imageOptions:--format string Pretty-print images using a Go template-H, --human Print sizes and dates in human readable format (default true)--no-trunc Don't truncate output-q, --quiet Only show numeric IDs docker image history centos:kaven.blog [root@izoq008ryseuupz ~]# docker image history centos:kaven.blog IMAGE CREATED CREATED BY SIZE COMMENT d0957ffdf8a2 20 months ago /bin/sh -c #(nop) CMD ["/bin/bash"] 0B <missing> 20 months ago /bin/sh -c #(nop) LABEL org.label-schema.sc… 0B <missing> 20 months ago /bin/sh -c #(nop) ADD file:0065316a41144e95b… 194MB <missing> 2 years ago /bin/sh -c #(nop) MAINTAINER https://github… 0B

只想展示鏡像操作歷史的簡要信息（IMAGE）。

docker image history -q centos:6 [root@izoq008ryseuupz ~]# docker image history -q centos:6 d0957ffdf8a2 <missing> <missing> <missing>

其他的命令選項可以自己試一試。

Docker Image Inspect

顯示鏡像的詳細信息。

docker image inspect --help [root@izoq008ryseuupz ~]# docker image inspect --helpUsage: docker image inspect [OPTIONS] IMAGE [IMAGE...]Display detailed information on one or more imagesOptions:-f, --format string Format the output using the given Go template docker image inspect centos:6 [root@izoq008ryseuupz ~]# docker image inspect centos:6 [{"Id": "sha256:d0957ffdf8a2ea8c8925903862b65a1b6850dbb019f88d45e927d3d5a3fa0c31","RepoTags": ["centos:6","centos:kaven.blog"],"RepoDigests": ["centos@sha256:dec8f471302de43f4cfcf82f56d99a5227b5ea1aa6d02fa56344986e1f4610e7"],"Parent": "","Comment": "","Created": "2019-03-14T21:20:11.486358099Z","Container": "d519f3e5c41d16388d3fba0dac626427b21deb98cce150dee80c180b9baf9435","ContainerConfig": {"Hostname": "d519f3e5c41d","Domainname": "","User": "","AttachStdin": false,"AttachStdout": false,"AttachStderr": false,"Tty": false,"OpenStdin": false,"StdinOnce": false,"Env": ["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"],"Cmd": ["/bin/sh","-c","#(nop) ","CMD [\"/bin/bash\"]"],"ArgsEscaped": true,"Image": "sha256:143abcd43bce45f4fd9ba51c7361051d7ea9e9e1eadb66e5c94a9c1b7754524f","Volumes": null,"WorkingDir": "","Entrypoint": null,"OnBuild": null,"Labels": {"org.label-schema.build-date": "20181006","org.label-schema.license": "GPLv2","org.label-schema.name": "CentOS Base Image","org.label-schema.schema-version": "1.0","org.label-schema.vendor": "CentOS"}},"DockerVersion": "18.06.1-ce","Author": "https://github.com/CentOS/sig-cloud-instance-images","Config": {"Hostname": "","Domainname": "","User": "","AttachStdin": false,"AttachStdout": false,"AttachStderr": false,"Tty": false,"OpenStdin": false,"StdinOnce": false,"Env": ["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"],"Cmd": ["/bin/bash"],"ArgsEscaped": true,"Image": "sha256:143abcd43bce45f4fd9ba51c7361051d7ea9e9e1eadb66e5c94a9c1b7754524f","Volumes": null,"WorkingDir": "","Entrypoint": null,"OnBuild": null,"Labels": {"org.label-schema.build-date": "20181006","org.label-schema.license": "GPLv2","org.label-schema.name": "CentOS Base Image","org.label-schema.schema-version": "1.0","org.label-schema.vendor": "CentOS"}},"Architecture": "amd64","Os": "linux","Size": 193901906,"VirtualSize": 193901906,"GraphDriver": {"Data": {"MergedDir": "/var/lib/docker/overlay2/ae0f8ac6c397e63561b52142c4e945909b8af2351d28e5af66f3490ff7078587/merged","UpperDir": "/var/lib/docker/overlay2/ae0f8ac6c397e63561b52142c4e945909b8af2351d28e5af66f3490ff7078587/diff","WorkDir": "/var/lib/docker/overlay2/ae0f8ac6c397e63561b52142c4e945909b8af2351d28e5af66f3490ff7078587/work"},"Name": "overlay2"},"RootFS": {"Type": "layers","Layers": ["sha256:af6bf1987c2eb07d73f33836b0d8fd825d7c785273526b077e46780e8b4b2ae9"]},"Metadata": {"LastTagTime": "2020-11-22T11:46:01.910880961+08:00"}} ]

其他的命令選項可以自己試一試。

Docker Image Import

從歸檔文件中創建鏡像。

docker image import --help [root@izoq008ryseuupz ~]# docker image import --helpUsage: docker image import [OPTIONS] file|URL|- [REPOSITORY[:TAG]]Import the contents from a tarball to create a filesystem imageOptions:-c, --change list Apply Dockerfile instruction to the created image-m, --message string Set commit message for imported image--platform string Set platform if server is multi-platform capable docker image import kaven.blog.tar centos:6.kaven [root@izoq008ryseuupz ~]# docker image import kaven.blog.tar centos:6.kaven sha256:3a568400d73096f71c5f5165f110414bb83e8024bca2ee3eea77336a194e920f

其他的命令選項可以自己試一試。

Docker Image Push

上傳鏡像到倉庫。

docker image push --help [root@izoq008ryseuupz ~]# docker image push --helpUsage: docker image push [OPTIONS] NAME[:TAG]Push an image or a repository to a registryOptions:--disable-content-trust Skip image signing (default true)

Docker Image Build

創建鏡像。

docker image build --help [root@izoq008ryseuupz ~]# docker image build --helpUsage: docker image build [OPTIONS] PATH | URL | -Build an image from a DockerfileOptions:--add-host list Add a custom host-to-IP mapping (host:ip)--build-arg list Set build-time variables--cache-from strings Images to consider as cache sources--cgroup-parent string Optional parent cgroup for the container--compress Compress the build context using gzip--cpu-period int Limit the CPU CFS (Completely Fair Scheduler) period--cpu-quota int Limit the CPU CFS (Completely Fair Scheduler) quota-c, --cpu-shares int CPU shares (relative weight)--cpuset-cpus string CPUs in which to allow execution (0-3, 0,1)--cpuset-mems string MEMs in which to allow execution (0-3, 0,1)--disable-content-trust Skip image verification (default true)-f, --file string Name of the Dockerfile (Default is 'PATH/Dockerfile')--force-rm Always remove intermediate containers--iidfile string Write the image ID to the file--isolation string Container isolation technology--label list Set metadata for an image-m, --memory bytes Memory limit--memory-swap bytes Swap limit equal to memory plus swap: '-1' to enable unlimited swap--network string Set the networking mode for the RUN instructions during build (default "default")--no-cache Do not use cache when building the image-o, --output stringArray Output destination (format: type=local,dest=path)--platform string Set platform if server is multi-platform capable--progress string Set type of progress output (auto, plain, tty). Use plain to show container output (default "auto")--pull Always attempt to pull a newer version of the image-q, --quiet Suppress the build output and print image ID on success--rm Remove intermediate containers after a successful build (default true)--secret stringArray Secret file to expose to the build (only if BuildKit enabled): id=mysecret,src=/local/secret--security-opt strings Security options--shm-size bytes Size of /dev/shm--squash Squash newly built layers into a single new layer--ssh stringArray SSH agent socket or keys to expose to the build (only if BuildKit enabled) (format: default|<id>[=<socket>|<key>[,<key>]])--stream Stream attaches to server to negotiate build context-t, --tag list Name and optionally a tag in the 'name:tag' format--target string Set the target build stage to build.--ulimit ulimit Ulimit options (default [])

這里會介紹將一個簡單的C語言程序，Build成一個Image。

先在當前目錄下創建一個hello.c程序。

vim hello.c

程序如下：

#include<stdio.h>int main() {printf("hello kaven\n");printf("this is docker\n"); }

不知道怎么退出VIM，可以看一下這篇博客：怎么保存退出 vim 編輯。

[root@izoq008ryseuupz ~]# ls hello.c kaven.blog.tar logs mall.jar [root@izoq008ryseuupz ~]# gcc hello.c -o hello [root@izoq008ryseuupz ~]# ls hello hello.c kaven.blog.tar logs mall.jar [root@izoq008ryseuupz ~]# ./hello hello kaven this is docker

在當前目錄下創建Dockerfile。

vim Dockerfile

輸入：

FROM scratch ADD hello / CMD ["/hello"]

現在看不懂沒關系，自己跟著體驗一次，之后的博客會詳細講解這些Dockerfile操作。

docker image build -t kaven/hello:v1 . [root@izoq008ryseuupz ~]# docker image build -t kaven/hello:v1 . Sending build context to Docker daemon 564.4MB Step 1/3 : FROM scratch---> Step 2/3 : ADD hello /---> 5d49f50c725b Step 3/3 : CMD ["/hello"]---> Running in b0b3bdce9078 Removing intermediate container b0b3bdce9078---> b1013ca7925d Successfully built b1013ca7925d Successfully tagged kaven/hello:v1

這樣kaven/hello:v1就有了。

Docker Image及Image命令詳解就介紹到這里。

寫博客是博主記錄自己的學習過程，如果有錯誤，請指正，謝謝！

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