Docker中基于php:7.1镜像安装opencv-python时出现cmake编译错误

问题复现 #

使用以下Dockerfile构建镜像时，基于php:7.1会报错，切换为php:8.0则正常执行：

FROM php:7.1

RUN apt-get update
RUN apt-get install -y python3-pip
RUN pip3 install opencv-python

错误信息 #

构建过程中触发cmake安装失败的错误，核心内容如下：

Running setup.py bdist_wheel for cmake: finished with status 'error'
Traceback (most recent call last):
  File "/tmp/pip-build-env-qno2yg1l/lib/python3.7/site-packages/skbuild/setuptools_wrap.py", line 613, in setup
    cmkr = cmaker.CMaker(cmake_executable)
  File "/tmp/pip-build-env-qno2yg1l/lib/python3.7/site-packages/skbuild/cmaker.py", line 141, in __init__
    self.cmake_version = get_cmake_version(self.cmake_executable)
  File "/tmp/pip-build-env-qno2yg1l/lib/python3.7/site-packages/skbuild/cmaker.py", line 96, in get_cmake_version
    "Problem with the CMake installation, aborting build. CMake executable is %s" % cmake_executable

...

Problem with the CMake installation, aborting build. CMake executable is cmake

----------------------------------------
Failed building wheel for cmake
Running setup.py clean for cmake
Failed to build cmake

原因分析 #

• php:7.1镜像基于Debian 9（stretch），自带的python3-pip版本为18.1，版本过低，无法正确处理cmake的二进制包，导致需要编译cmake但环境不满足要求。
• 新版本opencv-python依赖的cmake版本较高，Debian 9的默认软件源无法提供兼容版本，pip编译cmake时也会失败。
• php:8.0镜像基于Debian 11（bullseye），系统环境和软件包版本更现代，天然兼容最新opencv-python的安装需求。

解决方案 #

提供两种可行的修改方案：

方案一：升级pip并预先安装系统级cmake #

通过系统包管理器安装cmake，避免pip编译cmake，同时升级pip以适配现代Python包的安装逻辑：

FROM php:7.1

RUN apt-get update && apt-get install -y --no-install-recommends python3-pip cmake
RUN pip3 install --upgrade pip
RUN pip3 install opencv-python

方案二：指定兼容老环境的opencv-python版本 #

选择一个支持Python 3.7和Debian 9的旧版本opencv-python，例如4.5.5.62：

FROM php:7.1

RUN apt-get update && apt-get install -y --no-install-recommends python3-pip
RUN pip3 install --upgrade pip
RUN pip3 install opencv-python==4.5.5.62

内容的提问来源于stack exchange，提问作者neubert