(Docker notes): Build your own centos mirror

The official centos7 dockerfile

• centos7 dockerfile on github
  • sig-cloud-instance-images/docker/Dockerfile:

FROM scratch
ADD centos-7-x86_64-docker.tar.xz /

LABEL \
    org.label-schema.schema-version="1.0" \
    org.label-schema.name="CentOS Base Image" \
    org.label-schema.vendor="CentOS" \
    org.label-schema.license="GPLv2" \
    org.label-schema.build-date="20200809" \
    org.opencontainers.image.title="CentOS Base Image" \
    org.opencontainers.image.vendor="CentOS" \
    org.opencontainers.image.licenses="GPL-2.0-only" \
    org.opencontainers.image.created="2020-08-09 00:00:00+01:00"

CMD ["/bin/bash"]

• Most of the images in DockerHub are FROM scratch from this basic image , and then configure the required software and configuration to build
• Then we are based on the official image, plus some environment we need

Build your own centos mirror case

• Step ①: Create a dockerfile directory to store some files

cd /home
mkdir dockerfile

 

• Step ②: Create a dockerfile file, name it whatever you want, here is named mydockerfile

vim mydockerfile

• Step ③: Write dockerfile script instructions

FROM centos      # 基础镜像
MAINTAINER Aut<[email protected]>    # 作者信息

ENV MYPATH /usr/local    # 创建一个变量 存放一个值
WORKDIR $MYPATH    # 启动后的工作目录，就是进入容器后的默认目录

RUN yum -y install vim    # 执行指令安装 vim
RUN yum -y install net-tools    # 执行指令安装 net-tools

EXPOSE 80    # 暴露端口

CMD echo $MYPATH    # 输出 MYPATH 变量
CMD echo "----end----"    # 输出信息
CMD /bin/bash    # 启动后用bash命令行

• Step ④: Build the image

 docker build -f dockerfile文件路径 -t 镜像名:[tag] .

• Step ⑤: Prompt for successful construction

Successfully built f5932e99cf90
Successfully tagged mycentos:0.6

• Step ⑥: Test run

docker run -it mycentos:0.6

• Step ⑦: View the history through the history command, you can see how the mirror is made step by step

docker history 镜像ID