如果系统中没有python3.6，我可以在ubuntu18.04中安装python3.7吗？

Question

请仔细阅读问题，然后结束前作为副本，我相信用例是独特的。

我正在尝试创建一个只安装了python3.7的的对接映像，问题是如果我试图安装pip，命令还会安装python3.6，是我不想要的。

我正在修补的理想码头文件的相关部分如下

FROM ubuntu:18.04

# Upgrade installed packages
RUN apt-get update && apt-get upgrade -y && apt-get clean

# (...)

# Python package management and basic dependencies
RUN apt-get install -y python3.7 python3.7-dev python3.7-pip

# Register the version in alternatives
RUN update-alternatives --install /usr/bin/python python /usr/bin/python3.7 1

# Set python 3 as the default python
RUN update-alternatives --set python /usr/bin/python3.7

# Upgrade pip to latest version
RUN python -m ensurepip --upgrade

# (...)

这可能会失败，因为python3.7-pip似乎不存在；只有python3-pip才会失败，这就是安装python3.6-pip的原因。

我试着完全不安装pip并手动执行，如下所示

# (...)

RUN apt-get install -y python3.7 python3.7-dev

# (...)

RUN curl 'https://bootstrap.pypa.io/get-pip.py' > get-pip.py

RUN python get-pip.py pip --no-setuptools --no-wheel

如果出现此错误，将失败：

Traceback (most recent call last):
  File "get-pip.py", line 21492, in <module>
    main()
  File "get-pip.py", line 197, in main
    bootstrap(tmpdir=tmpdir)
  File "get-pip.py", line 82, in bootstrap
    import pip._internal
  File "/tmp/tmpbez2vju9/pip.zip/pip/_internal/__init__.py", line 40, in <module>
  File "/tmp/tmpbez2vju9/pip.zip/pip/_internal/cli/autocompletion.py", line 8, in <module>
  File "/tmp/tmpbez2vju9/pip.zip/pip/_internal/cli/main_parser.py", line 8, in <module>
  File "/tmp/tmpbez2vju9/pip.zip/pip/_internal/cli/cmdoptions.py", line 14, in <module>
ModuleNotFoundError: No module named 'distutils.util'

同样，安装python3-distutils会导致python3.6出现在系统中。

那么，是否可以在ubuntu18.04中只安装一个功能齐全的python 3.7，而不必安装python 3.6？

Answer 1

我看到两种选择：

1. 使用Ubuntu映像，使Python不受系统的影响。安装pyenv (https://github.com/pyenv/pyenv)，然后下载python3.7install，与系统的Python完全分离。

或

1. 使用标有3.7.3-拉伸或3.7.3-苗条拉伸(Debian)的Python官方图像

Answer 2

如果有人同意安装Python3.6作为一个副作用(python3.7-distutils介绍它，如OP所指出的)。这将安装Python3.7，使其成为默认值，并使用python3.7安装拥有最新可用的pip。

FROM ubuntu:18.04

# Upgrade installed packages
RUN apt-get update && apt-get upgrade -y && apt-get clean

# (...)

# Python package management and basic dependencies
RUN apt-get install -y curl python3.7 python3.7-dev python3.7-distutils

# Register the version in alternatives
RUN update-alternatives --install /usr/bin/python python /usr/bin/python3.7 1

# Set python 3 as the default python
RUN update-alternatives --set python /usr/bin/python3.7

# Upgrade pip to latest version
RUN curl -s https://bootstrap.pypa.io/get-pip.py -o get-pip.py && \
    python get-pip.py --force-reinstall && \
    rm get-pip.py


# (...)

Answer 3

@donhector的解决方案有两个微妙的问题：

1. 它将只安装过时的Python版本3.7.5。您需要回购ppa:deadsnakes来获得更新的版本。
2. 通过为python安装替代程序，它打破了用于Python2.x的python的约定。这可能会损坏，请参阅How to update-alternatives to Python 3 without breaking apt?

没有这些问题的解决办法是：

FROM ubuntu:18.04

# Upgrade installed packages
RUN apt update && apt upgrade -y && apt clean

# install python 3.7.10 (or newer)
RUN apt update && \
    apt install --no-install-recommends -y build-essential software-properties-common && \
    add-apt-repository -y ppa:deadsnakes/ppa && \
    apt install --no-install-recommends -y python3.7 python3.7-dev python3.7-distutils && \
    apt clean && rm -rf /var/lib/apt/lists/*

# Register the version in alternatives (and set higher priority to 3.7)
RUN update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.6 1
RUN update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.7 2

# Upgrade pip to latest version
RUN curl -s https://bootstrap.pypa.io/get-pip.py -o get-pip.py && \
    python3 get-pip.py --force-reinstall && \
    rm get-pip.py