• 第一條指令必須指定基礎(chǔ)鏡像
  FROM imageA:tag

• RUN 指定運行的命令
  一般是基于基礎(chǔ)容器，搭建基礎(chǔ)環(huán)境的操作，屬于build image的時候操作的；使用RUN指令的時候，最好不要寫多層RUN，使用下面一種形式，\分隔換行繼續(xù)寫就行了，不然層級增加，不利于鏡像可讀性和簡約性
  RUN direct-command
RUN ["executed-file","param1","param2"]

• CMD 指令只出容器啟動時需要的命令
  與RUN指令的使用實際不同；這里使用可執(zhí)行文件傳參數(shù)的時候，要注意使用雙引號，參數(shù)傳遞以后，docker會解析成json串
  CMD ["executed-file","param1","param2"]
CMD direct-command parames

• LABEL 添加鏡像標(biāo)簽
  LABEL key=value key2=value2

• MAINTAINER指定作者
  MAINTAINER author

• EXPOSE 對外端口
  EXPOSE端口指定的是外部訪問該容器的端口，與主機(jī)端口無關(guān)，如需要添加映射關(guān)系，使用-P參數(shù)
  EXPOSE 7171

• 設(shè)置環(huán)境變量
  ENV key=value key2=value2

• ADD 添加文件到鏡像中
  可以使用容器內(nèi)的絕對路徑，也可以使用相對路徑；file的格式原則上是不限制的，使用過程中可以根據(jù)實際情況評估
  ADD filename/url path

• COPY 拷貝文件
  COPY filename path

• ENTERPOINT
  啟動時的默認(rèn)命令，用法與RUN和CMD一樣
  如果同時寫了ENTERPOINT和CMD，二者可能會相互覆蓋，，？

• VOLUME掛載
  一般多設(shè)置于需要持久化存儲

• USER容器啟動用戶
  指定運行命令的層，執(zhí)行命令的身份
  USER user_name

• WORKDIR 工作目錄
  如果不存在會創(chuàng)建；存在以后多設(shè)置幾次也ok
  WORKDIR path

• ARG設(shè)置變量

• ONBUILD 基于當(dāng)前鏡像生成的子鏡像才會有的動作
  例如 ONBUILD CMD direct-command parames 這種

• STOPSIGNAL 容器退出時的系統(tǒng)指令

• HEALTHCHECK 健康檢查

>> 示例<<

FROM centos:7.1
MAINTAINER M_G
LABEL im_name="my_centos7"\
      im_desc="centos7.1byM_G"\
      im_version="1.0"
RUN /bin/echo "Testing-RUN1"\
    /bin/echo "Testing-RUN2"\
    /bin/echo "Testing-RUN3"\
    /bin/echo "The RUN instruction will execute any commands in a new layer on top of the current image and commit the results. The resulting committed image will be used for the next step in the Dockerfile"
RUN ["/bin/echo", "-c", "OtherMeth"]
EXPOSE 7788
CMD /bin/echo "CMD"

>> 示例運行結(jié)果 <<

docker build -t runtest/centos:7.1 .
Sending build context to Docker daemon  2.048kB
Step 1/7 : FROM centos:7.2.1511
 ---> 9aec5c5fe4ba
Step 2/7 : MAINTAINER M_G
 ---> Running in fd9773ab5d04
Removing intermediate container fd9773ab5d04
 ---> 5d049cf44ade
Step 3/7 : LABEL im_name="my_centos7"      im_desc="centos7.1byM_G"   im_version="1.0"
 ---> Running in dbe78be6937a
Removing intermediate container dbe78be6937a
 ---> 835de35557c0
Step 4/7 : RUN /bin/echo "Testing-RUN1" /bin/echo "Testing-RUN2"    /bin/echo "Testing-RUN3"    /bin/echo "The RUN instruction will execute any commands in a new layer on top of the current image and commit the results. The resulting committed image will be used for the next step in the Dockerfile"
 ---> Running in 200e155ce261
Testing-RUN1 /bin/echo Testing-RUN2 /bin/echo Testing-RUN3 /bin/echo The RUN instruction will execute any commands in a new layer on top of the current image and commit the results. The resulting committed image will be used for the next step in the Dockerfile
Removing intermediate container 200e155ce261
 ---> 6b20860bc949
Step 5/7 : RUN ["/bin/echo", "-c", "OtherMeth"]
 ---> Running in 39064900f238
-c OtherMeth
Removing intermediate container 39064900f238
 ---> 47e32cba5448
Step 6/7 : EXPOSE 7788
 ---> Running in c658c7ba76ea
Removing intermediate container c658c7ba76ea
 ---> e76255a7950f
Step 7/7 : CMD /bin/echo "CMD"
 ---> Running in 9ab1ff69c36d
Removing intermediate container 9ab1ff69c36d
 ---> 91f66f06b528
Successfully built 91f66f06b528
Successfully tagged runtest/centos:7.1

完成以上指令，docker images已經(jīng)創(chuàng)建成功，測試一下：

docker run -t -i runtest/centos:7.1 /bin/echo "TEST"
# output
TEST