013、Dockerfile构建镜像（2019-01-02 周三）

参考https://www.cnblogs.com/CloudMan6/p/6830067.html

 

Dockerfile构建镜像过程分析

 

root@docker-lab:~/111# ls    #    查看当前目录下存在Dockerfile文件

Dockerfile

root@docker-lab:~/111# cat Dockerfile    #    查看Dockerfile问价内容，运行centos容器，然后安装wget命令

FROM centos

RUN yum install -y wget

root@docker-lab:~/111# docker build -t centos-wget .    #    执行docker build 命令使用Dockerfile文件构建镜像

Sending build context to Docker daemon  2.048kB    #    发送build context（当前目录）下所有文件和子目录到dokcer daemon。建议当前目录不要存放与构建镜像无关的文件，耗时且容易失败

Step 1/2 : FROM centos    #    开始运行centos容器

latest: Pulling from library/centos    #    从Docker Hub下载centos镜像

a02a4930cb5d: Pull complete    

Digest: sha256:184e5f35598e333bfa7de10d8fb1cebb5ee4df5bc0f970bf2b1e7c7345136426

Status: Downloaded newer image for centos:latest

---> 1e1148e4cc2c    #    centos容器启动成功，id：1e1148e4cc2c

Step 2/2 : RUN yum install -y wget    #    开始安装wget命令

---> Running in a127bab51f51    #    运行临时容器 a127bab51f51

Loaded plugins: fastestmirror, ovl

Determining fastest mirrors

* base: mirrors.huaweicloud.com

* extras: mirrors.neusoft.edu.cn

* updates: mirrors.neusoft.edu.cn

Resolving Dependencies

--> Running transaction check

---> Package wget.x86_64 0:1.14-18.el7 will be installed

--> Finished Dependency Resolution

 

Dependencies Resolved

 

================================================================================

Package         Arch              Version                Repository       Size

================================================================================

Installing:

wget            x86_64            1.14-18.el7            base            547 k

 

Transaction Summary

================================================================================

Install  1 Package

 

Total download size: 547 k

Installed size: 2.0 M

Downloading packages:

warning: /var/cache/yum/x86_64/7/base/packages/wget-1.14-18.el7.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID f4a80eb5: NOKEY

Public key for wget-1.14-18.el7.x86_64.rpm is not installed

Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

Importing GPG key 0xF4A80EB5:

Userid     : "CentOS-7 Key (CentOS 7 Official Signing Key) <security@centos.org>"

Fingerprint: 6341 ab27 53d7 8a78 a7c2 7bb1 24c6 a8a7 f4a8 0eb5

Package    : centos-release-7-6.1810.2.el7.centos.x86_64 (@CentOS)

From       : /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

Running transaction check

Running transaction test

Transaction test succeeded

Running transaction

  Installing : wget-1.14-18.el7.x86_64                                      1/1

install-info: No such file or directory for /usr/share/info/wget.info.gz

  Verifying  : wget-1.14-18.el7.x86_64                                      1/1

 

Installed:

  wget.x86_64 0:1.14-18.el7                                                     

 

Complete!

Removing intermediate container a127bab51f51    #    删除临时容器 a127bab51f51 

---> 8486cf558bf9

Successfully built 8486cf558bf9    #    成功构建镜像 8486cf558bf9

Successfully tagged centos-wget:latest    

 

root@docker-lab:~/111# docker images    #    查看镜像列表，确认centos-wget 镜像创建成功

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

centos-wget         latest              8486cf558bf9        59 seconds ago      272MB

centos              latest              1e1148e4cc2c        3 weeks ago         202MB

root@docker-lab:~/111# docker history centos-wget    #    查看镜像centos-wget 构建记录，即docker的分层结构

IMAGE               CREATED              CREATED BY                                      SIZE                COMMENT

8486cf558bf9        About a minute ago   /bin/sh -c yum install -y wget                  70.7MB              

1e1148e4cc2c        3 weeks ago          /bin/sh -c #(nop)  CMD ["/bin/bash"]            0B                  

<missing>           3 weeks ago          /bin/sh -c #(nop)  LABEL org.label-schema.sc…   0B                  

<missing>           3 weeks ago          /bin/sh -c #(nop) ADD file:6f877549795f4798a…   202MB