创建镜像
2021-06-08 大约 7 分钟
当运行容器时，使用的镜像如果在本地中不存在，docker 就会自动从 docker 镜像仓库中下载，默认是从 Docker Hub 公共镜像源下载。
# 查看本机镜像
我们可以使用 docker images 来列出本地主机上的镜像。
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu latest 7e0aa2d69a15 6 weeks ago 72.7MB
docker/getting-started latest 3ba8f2ff0727 2 months ago 27.9MB
hello-world latest d1165f221234 3 months ago 13.3kB
ubuntu 15.10 9b9cb95443b5 4 years ago 137MB
training/webapp latest 6fae60ef3446 6 years ago 349MB
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$
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各个选项说明:
- **REPOSITORY：**表示镜像的仓库源
- **TAG：**镜像的标签
- **IMAGE ID：**镜像ID
- **CREATED：**镜像创建时间
- **SIZE：**镜像大小
同一仓库源可以有多个 TAG，代表这个仓库源的不同个版本，如 ubuntu 仓库源里，有 15.10、14.04 等多个不同的版本，我们使用 REPOSITORY:TAG 来定义不同的镜像。
所以，我们如果要使用版本为15.10的ubuntu系统镜像来运行容器时，命令如下：
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ docker run -t -i ubuntu:15.10 /bin/bash
root@7a90e165a7c9:/# ls
bin boot dev etc home lib lib64 media mnt opt proc root run sbin srv sys tmp usr var
root@7a90e165a7c9:/#
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参数说明：
- -i: 交互式操作。
- -t: 终端。
- ubuntu:15.10: 这是指用 ubuntu 15.10 版本镜像为基础来启动容器。
- /bin/bash：放在镜像名后的是命令，这里我们希望有个交互式 Shell，因此用的是 /bin/bash。
提示
如果你不指定一个镜像的版本标签，例如你只使用 ubuntu，docker 将默认使用 ubuntu:latest 镜像。
# 获取新镜像
当我们在本地主机上使用一个不存在的镜像时 Docker 就会自动下载这个镜像。如果我们想预先下载这个镜像，我们可以使用 docker pull 命令来下载它。
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ docker pull ubuntu:13.10
13.10: Pulling from library/ubuntu
Image docker.io/library/ubuntu:13.10 uses outdated schema1 manifest format. Please upgrade to a schema2 image for better future compatibility. More information at https://docs.docker.com/registry/spec/deprecated-schema-v1/
a3ed95caeb02: Pull complete
0d8710fc57fd: Pull complete
5037c5cd623d: Pull complete
83b53423b49f: Pull complete
e9e8bd3b94ab: Pull complete
7db00e6b6e5e: Pull complete
Digest: sha256:403105e61e2d540187da20d837b6a6e92efc3eb4337da9c04c191fb5e28c44dc
Status: Downloaded newer image for ubuntu:13.10
docker.io/library/ubuntu:13.10
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$
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下载完成后，我们可以直接使用这个镜像来运行容器。
# 查找镜像
我们可以从 Docker Hub 网站来搜索镜像，Docker Hub 网址为： https://hub.docker.com/，我们也可以使用 docker search 命令来搜索镜像。比如我们需要一个 httpd 的镜像来作为我们的 web 服务。我们可以通过 docker search 命令搜索 httpd 来寻找适合我们的镜像。
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ docker search httpd
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
httpd The Apache HTTP Server Project 3529 [OK]
centos/httpd-24-centos7 Platform for running Apache httpd 2.4 or bui… 40
centos/httpd 34 [OK]
arm32v7/httpd The Apache HTTP Server Project 9
salim1983hoop/httpd24 Dockerfile running apache config 2 [OK]
solsson/httpd-openidc mod_auth_openidc on official httpd image, ve… 2 [OK]
hypoport/httpd-cgi httpd-cgi 2 [OK]
publici/httpd httpd:latest 1 [OK]
clearlinux/httpd httpd HyperText Transfer Protocol (HTTP) ser… 1
jonathanheilmann/httpd-alpine-rewrite httpd:alpine with enabled mod_rewrite 1 [OK]
lead4good/httpd-fpm httpd server which connects via fcgi proxy h… 1 [OK]
dockerpinata/httpd 1
manageiq/httpd Container with httpd, built on CentOS for Ma… 1 [OK]
inanimate/httpd-ssl A play container with httpd, ssl enabled, an… 1 [OK]
dariko/httpd-rproxy-ldap Apache httpd reverse proxy with LDAP authent… 1 [OK]
centos/httpd-24-centos8 0
appertly/httpd Customized Apache HTTPD that uses a PHP-FPM … 0 [OK]
amd64/httpd The Apache HTTP Server Project 0
e2eteam/httpd 0
manageiq/httpd_configmap_generator Httpd Configmap Generator 0 [OK]
trollin/httpd 0
manasip/httpd 0
ysli/httpd Httpd for DeepWeb 0 [OK]
itsziget/httpd24 Extended HTTPD Docker image based on the off… 0 [OK]
interlutions/httpd httpd docker image with debian-based config … 0 [OK]
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$
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NAME: 镜像仓库源的名称
DESCRIPTION: 镜像的描述
OFFICIAL: 是否 docker 官方发布
stars: 类似 Github 里面的 star，表示点赞、喜欢的意思。
AUTOMATED: 自动构建。
# 拉取镜像
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ docker pull httpd
Using default tag: latest
latest: Pulling from library/httpd
69692152171a: Pull complete
7284b4e0cc7b: Pull complete
3678b2d55ccd: Pull complete
aeb67982a725: Pull complete
06954f8169fd: Pull complete
Digest: sha256:48bae0ac5d0d75168f1c1282c0eb21b43302cb1b5c5dc9fa3b4a758ccfb36fe9
Status: Downloaded newer image for httpd:latest
docker.io/library/httpd:latest
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ docker run httpd
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下载完成后，我们就可以使用这个镜像了。
# 创建镜像
当我们从 docker 镜像仓库中下载的镜像不能满足我们的需求时，我们可以通过以下两种方式对镜像进行更改。
- 1、从已经创建的容器中更新镜像，并且提交这个镜像
- 2、使用 Dockerfile 指令来创建一个新的镜像
# 更新镜像
更新镜像之前，我们需要使用镜像来创建一个容器。
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ docker run -t -i ubuntu:15.10 /bin/bash
root@f601f176aa29:/# apt-get update
Ign http://archive.ubuntu.com wily InRelease
Ign http://archive.ubuntu.com wily-updates InRelease
Ign http://archive.ubuntu.com wily-security InRelease
Ign http://archive.ubuntu.com wily Release.gpg
Ign http://archive.ubuntu.com wily-updates Release.gpg
Ign http://archive.ubuntu.com wily-security Release.gpg
Ign http://archive.ubuntu.com wily Release
Ign http://archive.ubuntu.com wily-updates Release
Ign http://archive.ubuntu.com wily-security Release
....
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使用docker ps -a找到创建的容器的id。我们可以通过命令 docker commit 来提交容器副本。
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ docker commit -m="has update" -a="runoob" f601f176aa29 runoob/ubuntu:v2
sha256:3a9b73618178c6f0ce4ec1c287de0787b84fddedfa3eff058af358723b3b19e9
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$
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各个参数说明：
- -m: 提交的描述信息
- -a: 指定镜像作者
- **e218edb10161：**容器 ID
- runoob/ubuntu:v2: 指定要创建的目标镜像名
我们可以使用 docker images 命令来查看我们的新镜像 runoob/ubuntu:v2：
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
runoob/ubuntu v2 3a9b73618178 4 minutes ago 137MB # 此处
httpd latest 39c2d1c93266 11 days ago 138MB
ubuntu latest 7e0aa2d69a15 6 weeks ago 72.7MB
docker/getting-started latest 3ba8f2ff0727 2 months ago 27.9MB
hello-world latest d1165f221234 3 months ago 13.3kB
ubuntu 15.10 9b9cb95443b5 4 years ago 137MB
training/webapp latest 6fae60ef3446 6 years ago 349MB
ubuntu 13.10 7f020f7bf345 6 years ago 185MB
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$
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使用我们的新镜像 runoob/ubuntu 来启动一个容器
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ docker run -t -i runoob/ubuntu:v2 /bin/bash
root@28c174d9b40f:/# ls
bin boot dev etc home lib lib64 media mnt opt proc root run sbin srv sys tmp usr var
root@28c174d9b40f:/#
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# 构建镜像
我们使用命令 docker build ， 从零开始来创建一个新的镜像。为此，我们需要创建一个 Dockerfile 文件，其中包含一组指令来告诉 Docker 如何构建我们的镜像。
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$ cat Dockerfile
FROM centos:7
MAINTAINER Fisher "fisher@sudops.com"
RUN useradd "runoob"
RUN /bin/echo 'runoob:123456' |chpasswd
RUN /bin/echo -e "LANG=\"en_US.UTF-8\"" >/etc/default/local
EXPOSE 22
EXPOSE 80
CMD /usr/sbin/sshd -D
wangyawei@yaweidediannao:/mnt/c/Users/ASUS$
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每一个指令都会在镜像上创建一个新的层，每一个指令的前缀都必须是大写的。
第一条FROM，指定使用哪个镜像源
RUN 指令告诉docker 在镜像内执行命令，安装了什么。。。
构建镜像；
wangyawei@yaweidediannao:~/test$ docker build -t runoob/centos:7 .
[+] Building 34.4s (8/8) FINISHED
=> [internal] load build definition from Dockerfile 0.1s
=> => transferring dockerfile: 286B 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [internal] load metadata for docker.io/library/centos:7 16.9s
=> [1/4] FROM docker.io/library/centos:7@sha256:0f4ec88e21daf75124b8a9e5ca03c37a5e937e0e108a255d890492430789b60e 14.5s
=> => resolve docker.io/library/centos:7@sha256:0f4ec88e21daf75124b8a9e5ca03c37a5e937e0e108a255d890492430789b60e 0.0s
=> => sha256:0f4ec88e21daf75124b8a9e5ca03c37a5e937e0e108a255d890492430789b60e 1.20kB / 1.20kB 0.0s
=> => sha256:e4ca2ed0202e76be184e75fb26d14bf974193579039d5573fb2348664deef76e 529B / 529B 0.0s
=> => sha256:8652b9f0cb4c0599575e5a003f5906876e10c1ceb2ab9fe1786712dac14a50cf 2.75kB / 2.75kB 0.0s
=> => sha256:2d473b07cdd5f0912cd6f1a703352c82b512407db6b05b43f2553732b55df3bc 76.10MB / 76.10MB 9.6s
=> => extracting sha256:2d473b07cdd5f0912cd6f1a703352c82b512407db6b05b43f2553732b55df3bc 4.6s
=> [2/4] RUN useradd "runoob" 1.6s
=> [3/4] RUN /bin/echo 'runoob:123456' |chpasswd 0.6s
=> [4/4] RUN /bin/echo -e "LANG="en_US.UTF-8"" >/etc/default/local 0.5s
=> exporting to image 0.1s
=> => exporting layers 0.1s
=> => writing image sha256:bfc14340e7fa9da9a815afcc55a7d7c5d3a661965f1d693fe84468fab99b5739 0.0s
=> => naming to docker.io/runoob/centos:7 0.0s
Use 'docker scan' to run Snyk tests against images to find vulnerabilities and learn how to fix them
wangyawei@yaweidediannao:~/test$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
runoob/centos 7 bfc14340e7fa 56 seconds ago 204MB # 创建的镜像
runoob/ubuntu v2 3a9b73618178 44 minutes ago 137MB
httpd latest 39c2d1c93266 11 days ago 138MB
ubuntu latest 7e0aa2d69a15 6 weeks ago 72.7MB
docker/getting-started latest 3ba8f2ff0727 2 months ago 27.9MB
hello-world latest d1165f221234 3 months ago 13.3kB
ubuntu 15.10 9b9cb95443b5 4 years ago 137MB
training/webapp latest 6fae60ef3446 6 years ago 349MB
ubuntu 13.10 7f020f7bf345 6 years ago 185MB
wangyawei@yaweidediannao:~/test$
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参数说明：
- -t ：指定要创建的目标镜像名
- . ：Dockerfile 文件所在目录，可以指定Dockerfile 的绝对路径
# 创建容器
wangyawei@yaweidediannao:~/test$ docker run -t -i runoob/centos:7 /bin/bash
[root@1b9dbb4f6ced /]# ls
anaconda-post.log bin dev etc home lib lib64 media mnt opt proc root run sbin srv sys tmp usr var
[root@1b9dbb4f6ced /]#
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# 设置镜像标签
我们可以使用 docker tag 命令，为镜像添加一个新的标签。
wangyawei@yaweidediannao:~/test$ docker tag bfc14340e7fa runoob/centos:dev
wangyawei@yaweidediannao:~/test$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
runoob/centos 7 bfc14340e7fa 8 minutes ago 204MB # 老标签
runoob/centos dev bfc14340e7fa 8 minutes ago 204MB # 新标签
runoob/ubuntu v2 3a9b73618178 51 minutes ago 137MB
httpd latest 39c2d1c93266 11 days ago 138MB
ubuntu latest 7e0aa2d69a15 6 weeks ago 72.7MB
docker/getting-started latest 3ba8f2ff0727 2 months ago 27.9MB
hello-world latest d1165f221234 3 months ago 13.3kB
ubuntu 15.10 9b9cb95443b5 4 years ago 137MB
training/webapp latest 6fae60ef3446 6 years ago 349MB
ubuntu 13.10 7f020f7bf345 6 years ago 185MB
wangyawei@yaweidediannao:~/test$
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