## docker分層 用來構建docker鏡像的文件  ## 常用命令  ~~~ CMD 指定容器啟動的時候運行的命令，只有最后一個會生效，可被替代 ENTRYPOINT 指定容器啟動的時候運行的命令，可以追加命令 ONBUILD 當構建一個被繼承Dockerfile，這時候會運行ONBUILD指令，觸發指令 COPY 將文件拷貝到鏡像中，類似ADD ENV 設置環境變量 ~~~ ## 實戰測試 DockerHub中大多數鏡像都是從這個基礎鏡像來的，FROM scratch，然后配置需要的軟件和配置 示例構建一個centos ~~~ FROM centos MAINTAINER wzj<wusir666666@163.com> ENV MYPATH /usr/local WORKDIR $MYPATH RUN yum -y install vim RUN yum -y install net-tools EXPOSE 80 CMD echo $MYPATH CMD echo "---end---" CMD /bin/bash ~~~ 列出鏡像變更歷史（構建步驟）：docker history?鏡像id ?ENTRYPOINT?和?CMD區別 ~~~ CMD 指定容器啟動的時候運行的命令，只有最后一個會生效，可被替代 ENTRYPOINT 指定容器啟動的時候運行的命令，可以追加命令 ~~~ 測試CMD ~~~ 構建鏡像： FROM centos CMD ["ls", "-a"] 運行后顯示 E:\study\docker\dockerfile>docker run centos_test:v1 . .. .dockerenv bin dev etc home lib lib64 lost+found media mnt opt proc root run sbin srv sys tmp usr var 如果此時想要追加一個命令 -l E:\study\docker\dockerfile>docker run centos_test:v1 -l docker: Error response from daemon: OCI runtime create failed: container_linux.go:349: starting container process caused "exec: \"-l\": executable file not found in $PATH": unknown. CMD情況下 -l 替換了 ["ls", "-a"]，但是-l不是一個有效命令，所以報錯 ~~~ 測試ENTRYPOINT ~~~ 構建鏡像： FROM centos ENTRYPOINT ["ls", "-a"] 運行后顯示 E:\study\docker\dockerfile>docker run centos_test:v1 . .. .dockerenv bin dev etc home lib lib64 lost+found media mnt opt proc root run sbin srv sys tmp usr var 如果此時想要追加一個命令 -l E:\study\docker\dockerfile>docker run centos_test1:v1 -l total 56 drwxr-xr-x 1 root root 4096 Nov 25 09:23 . drwxr-xr-x 1 root root 4096 Nov 25 09:23 .. -rwxr-xr-x 1 root root 0 Nov 25 09:23 .dockerenv lrwxrwxrwx 1 root root 7 May 11 2019 bin -> usr/bin drwxr-xr-x 5 root root 340 Nov 25 09:23 dev drwxr-xr-x 1 root root 4096 Nov 25 09:23 etc drwxr-xr-x 2 root root 4096 May 11 2019 home lrwxrwxrwx 1 root root 7 May 11 2019 lib -> usr/lib lrwxrwxrwx 1 root root 9 May 11 2019 lib64 -> usr/lib64 drwx------ 2 root root 4096 Aug 9 21:40 lost+found drwxr-xr-x 2 root root 4096 May 11 2019 media drwxr-xr-x 2 root root 4096 May 11 2019 mnt drwxr-xr-x 2 root root 4096 May 11 2019 opt dr-xr-xr-x 124 root root 0 Nov 25 09:23 proc dr-xr-x--- 2 root root 4096 Aug 9 21:40 root drwxr-xr-x 11 root root 4096 Aug 9 21:40 run lrwxrwxrwx 1 root root 8 May 11 2019 sbin -> usr/sbin drwxr-xr-x 2 root root 4096 May 11 2019 srv dr-xr-xr-x 13 root root 0 Nov 25 09:23 sys drwxrwxrwt 7 root root 4096 Aug 9 21:40 tmp drwxr-xr-x 12 root root 4096 Aug 9 21:40 usr drwxr-xr-x 20 root root 4096 Aug 9 21:40 var ~~~