添加新依赖项时包卸载？

Question

在 docker -基于 alpine linux- 的入口点脚本中，我有以下几行：

#!/bin/sh
echo "============== START ============"
echo $@
NOLOAD=0
FILE=""

RET=1

if [ !  -f /initialized ]; then
  echo "not initialized"
  apk add --virtual .init-deps bash
  echo "bash installed"
  echo "Building from server"
  apk add --virtual .init-deps git
  echo "git installed"
  bash load_git.sh "${GIT_SERVER}" "${GIT_USERNAME}" "${GIT_PASSWORD}" "${GIT_BRANCH}"
  RET=$?
  echo cloning done
fi
echo "just before purging all dependencies"
apk --purge del .init-deps

我希望 bash 安装，以及 git 和运行使用 bash 的 load_git.sh 脚本。我每隔一行记录一次文学，但得到了一些奇怪的结果 - 在 load_git.sh 脚本甚至运行:

之前

============== START ============

not initialized
(1/6) Installing ncurses-terminfo-base (6.1_p20191130-r0)
(2/6) Installing ncurses-terminfo (6.1_p20191130-r0)
(3/6) Installing ncurses-libs (6.1_p20191130-r0)
(4/6) Installing readline (8.0.1-r0)
(5/6) Installing bash (5.0.11-r1)
Executing bash-5.0.11-r1.post-install
(6/6) Installing .init-deps (20200109.202215)
Executing busybox-1.31.1-r8.trigger
OK: 18 MiB in 24 packages
bash installed
Building from server
(1/12) Installing ca-certificates (20191127-r0)
(2/12) Installing nghttp2-libs (1.40.0-r0)
(3/12) Installing libcurl (7.67.0-r0)
(4/12) Installing expat (2.2.9-r1)
(5/12) Installing pcre2 (10.34-r1)
(6/12) Installing git (2.24.1-r0)
(7/12) Upgrading .init-deps (20200109.202215 -> 20200109.202216)
(8/12) Purging bash (5.0.11-r1)
Executing bash-5.0.11-r1.pre-deinstall
(9/12) Purging readline (8.0.1-r0)
(10/12) Purging ncurses-libs (6.1_p20191130-r0)
(11/12) Purging ncurses-terminfo (6.1_p20191130-r0)
(12/12) Purging ncurses-terminfo-base (6.1_p20191130-r0)
Executing busybox-1.31.1-r8.trigger
Executing ca-certificates-20191127-r0.trigger
OK: 25 MiB in 25 packages
git installed
/init.sh: line 17: bash: not found
cloning done
outside if statement to get source
just before purging all dependencies
Build failed, starting shell

我无法理解在安装 git 时它也会清除 bash 的事实，这根本没有意义。

编辑：只有在 synology nas 中通过 ssh 连接启动 docker 时才会发生这种情况，当使用本地 docker 图像并启动它时在本地它工作得很好。

Answer 1

我尝试在远程计算机上重现并使用以下脚本进行管理：

#!/bin/sh
if [ !  -f /initialized ]; then
  apk add --virtual .init-deps bash
  apk add --virtual .init-deps git
  bash -c "bash works"
fi

但连续运行有不同的结果：

ubuntu@dev:~$ docker run c81a2d3a5f6b
fetch http://dl-cdn.alpinelinux.org/alpine/v3.11/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.11/community/x86_64/APKINDEX.tar.gz
(1/6) Installing ncurses-terminfo-base (6.1_p20191130-r0)
(2/6) Installing ncurses-terminfo (6.1_p20191130-r0)
(3/6) Installing ncurses-libs (6.1_p20191130-r0)
(4/6) Installing readline (8.0.1-r0)
(5/6) Installing bash (5.0.11-r1)
Executing bash-5.0.11-r1.post-install
(6/6) Installing .init-deps (20200109.224208)
Executing busybox-1.31.1-r8.trigger
OK: 15 MiB in 20 packages
(1/12) Installing ca-certificates (20191127-r0)
(2/12) Installing nghttp2-libs (1.40.0-r0)
(3/12) Installing libcurl (7.67.0-r0)
(4/12) Installing expat (2.2.9-r1)
(5/12) Installing pcre2 (10.34-r1)
(6/12) Installing git (2.24.1-r0)
(7/12) Upgrading .init-deps (20200109.224208 -> 20200109.224209)
(8/12) Purging bash (5.0.11-r1)
Executing bash-5.0.11-r1.pre-deinstall
(9/12) Purging readline (8.0.1-r0)
(10/12) Purging ncurses-libs (6.1_p20191130-r0)
(11/12) Purging ncurses-terminfo (6.1_p20191130-r0)
(12/12) Purging ncurses-terminfo-base (6.1_p20191130-r0)
Executing busybox-1.31.1-r8.trigger
Executing ca-certificates-20191127-r0.trigger
OK: 22 MiB in 21 packages
/test.sh: line 5: bash: not found

ubuntu@dev:~$ docker run c81a2d3a5f6b
fetch http://dl-cdn.alpinelinux.org/alpine/v3.11/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.11/community/x86_64/APKINDEX.tar.gz
(1/6) Installing ncurses-terminfo-base (6.1_p20191130-r0)
(2/6) Installing ncurses-terminfo (6.1_p20191130-r0)
(3/6) Installing ncurses-libs (6.1_p20191130-r0)
(4/6) Installing readline (8.0.1-r0)
(5/6) Installing bash (5.0.11-r1)
Executing bash-5.0.11-r1.post-install
(6/6) Installing .init-deps (20200109.224207)
Executing busybox-1.31.1-r8.trigger
OK: 15 MiB in 20 packages
OK: 15 MiB in 20 packages
bash works

所以我认为这是apk中的时间问题

Answer 2

看起来这里发生的事情是 apk add --virtual .init-deps 选项创建了一个虚拟包并使其依赖于刚刚安装的其他包。当你第二次这样做时，它会创建一个新的虚拟包（仅）依赖于第二组包，并将虚拟包升级到新版本；当您这样做时，第一组软件包会自动卸载。

这里有两个简单的解决方法：从两行中删除这个 --virtual .init-deps 选项，或者将所有安装合并到一个 apk add 行中。

（在容器启动时下载包通常不是很好的做法，特别是因为删除和重新创建容器是一个相当常规的操作。更好的做法是在图像的 Dockerfile 中执行一次

RUN apk add bash git

还要考虑您是否真的需要这些工具中的任何一个来运行将应用程序打包到您的映像中。）

添加新依赖项时包卸载？

package uninstalls when adding a new dependency?

bash

shell

docker

alpine