RUN 主要用于在Image里执行指令，比如安装软件，下载文件等

  1. apt-get update
  2. apt-get install wget
  3. wget https://github.com/ipinfo/cli/releases/download/ipinfo-2.0.1/ipinfo_2.0.1_linux_amd64.tar.gz
  4. tar zxf ipinfo_2.0.1_linux_amd64.tar.gz
  5. mv ipinfo_2.0.1_linux_amd64 /usr/bin/ipinfo
  6. rm -rf ipinfo_2.0.1_linux_amd64.tar.gz

Dockerfile

  1. FROM ubuntu:20.04
  2. RUN apt-get update
  3. RUN apt-get install -y wget
  4. RUN wget https://github.com/ipinfo/cli/releases/download/ipinfo-2.0.1/ipinfo_2.0.1_linux_amd64.tar.gz
  5. RUN tar zxf ipinfo_2.0.1_linux_amd64.tar.gz
  6. RUN mv ipinfo_2.0.1_linux_amd64 /usr/bin/ipinfo
  7. RUN rm -rf ipinfo_2.0.1_linux_amd64.tar.gz

镜像的大小和分层

  1. $ docker image ls
  2. REPOSITORY   TAG       IMAGE ID       CREATED         SIZE
  3. ipinfo       latest    97bb429363fb   4 minutes ago   138MB
  4. ubuntu       21.04     478aa0080b60   4 days ago      74.1MB
  5. $ docker image history 97b
  6. IMAGE          CREATED         CREATED BY                                      SIZE      COMMENT
  7. 97bb429363fb   4 minutes ago   RUN /bin/sh -c rm -rf ipinfo_2.0.1_linux_amd…   0B        buildkit.dockerfile.v0
  8. <missing>      4 minutes ago   RUN /bin/sh -c mv ipinfo_2.0.1_linux_amd64 /…   9.36MB    buildkit.dockerfile.v0
  9. <missing>      4 minutes ago   RUN /bin/sh -c tar zxf ipinfo_2.0.1_linux_am…   9.36MB    buildkit.dockerfile.v0
  10. <missing>      4 minutes ago   RUN /bin/sh -c wget https://github.com/ipinf…   4.85MB    buildkit.dockerfile.v0
  11. <missing>      4 minutes ago   RUN /bin/sh -c apt-get install -y wget # bui…   7.58MB    buildkit.dockerfile.v0
  12. <missing>      4 minutes ago   RUN /bin/sh -c apt-get update # buildkit        33MB      buildkit.dockerfile.v0
  13. <missing>      4 days ago      /bin/sh -c #(nop)  CMD ["/bin/bash"]            0B
  14. <missing>      4 days ago      /bin/sh -c mkdir -p /run/systemd && echo 'do…   7B
  15. <missing>      4 days ago      /bin/sh -c [ -z "$(apt-get indextargets)" ]     0B
  16. <missing>      4 days ago      /bin/sh -c set -xe   && echo '#!/bin/sh' > /…   811B
  17. <missing>      4 days ago      /bin/sh -c #(nop) ADD file:d6b6ba642344138dc…   74.1MB
每一行的RUN命令都会产生一层image layer, 导致镜像的臃肿。

改进版Dockerfile

  1. FROM ubuntu:20.04
  2. RUN apt-get update && \
  3.     apt-get install -y wget && \
  4.     wget https://github.com/ipinfo/cli/releases/download/ipinfo-2.0.1/ipinfo_2.0.1_linux_amd64.tar.gz && \
  5.     tar zxf ipinfo_2.0.1_linux_amd64.tar.gz && \
  6.     mv ipinfo_2.0.1_linux_amd64 /usr/bin/ipinfo && \
  7.     rm -rf ipinfo_2.0.1_linux_amd64.tar.gz
  1. $ docker image ls
  2. REPOSITORY   TAG       IMAGE ID       CREATED          SIZE
  3. ipinfo-new   latest    fe551bc26b92   5 seconds ago    124MB
  4. ipinfo       latest    97bb429363fb   16 minutes ago   138MB
  5. ubuntu       21.04     478aa0080b60   4 days ago       74.1MB
  6. $ docker image history fe5
  7. IMAGE          CREATED          CREATED BY                                      SIZE      COMMENT
  8. fe551bc26b92   16 seconds ago   RUN /bin/sh -c apt-get update &&     apt-get…   49.9MB    buildkit.dockerfile.v0
  9. <missing>      4 days ago       /bin/sh -c #(nop)  CMD ["/bin/bash"]            0B
  10. <missing>      4 days ago       /bin/sh -c mkdir -p /run/systemd && echo 'do…   7B
  11. <missing>      4 days ago       /bin/sh -c [ -z "$(apt-get indextargets)" ]     0B
  12. <missing>      4 days ago       /bin/sh -c set -xe   && echo '#!/bin/sh' > /…   811B
  13. <missing>      4 days ago       /bin/sh -c #(nop) ADD file:d6b6ba642344138dc…   74.1MB
  14. $