安装mysqlclient遇ModuleNotFoundError及编译依赖错误求助

问题概述 #

尝试安装mysqlclient时先出现ModuleNotFoundError: No module named 'MySQLdb'，执行pip install mysqlclient又报错编译wheel失败，提示无法找到有效的pkg-config名称，需手动指定MYSQLCLIENT_CFLAGS和MYSQLCLIENT_LDFLAGS环境变量，完整报错日志：

kanishka@kanishka-VivoBook-ASUSLaptop-X512FJ-X512FJ:~/Documents/Ceylone Soft/bcj_dev_back_end$ pip install mysqlclient

Collecting mysqlclient
  Using cached mysqlclient-2.2.4.tar.gz (90 kB)
  Installing build dependencies ... done
  Getting requirements to build wheel ... error
  ERROR: Command errored out with exit status 1:
   command: '/home/kanishka/Documents/Ceylone Soft/bcj_dev_back_end/BuyChem/bin/python3' /tmp/tmp81chy8bh get_requires_for_build_wheel /tmp/tmpbjs9srac
       cwd: /tmp/pip-install-ulmsnxu3/mysqlclient
  Complete output (24 lines):
  Trying pkg-config --exists mysqlclient
  Command 'pkg-config --exists mysqlclient' returned non-zero exit status 1.
  Trying pkg-config --exists mariadb
  Command 'pkg-config --exists mariadb' returned non-zero exit status 1.
  Trying pkg-config --exists libmariadb
  Command 'pkg-config --exists libmariadb' returned non-zero exit status 1.
  Traceback (most recent call last):
    File "/tmp/tmp81chy8bh", line 280, in <module>
      main()
    File "/tmp/tmp81chy8bh", line 263, in main
      json_out['return_val'] = hook(**hook_input['kwargs'])
    File "/tmp/tmp81chy8bh", line 114, in get_requires_for_build_wheel
      return hook(config_settings)
    File "/tmp/pip-build-env-csmolp15/overlay/lib/python3.8/site-packages/setuptools/build_meta.py", line 325, in get_requires_for_build_wheel
      return self._get_build_requires(config_settings, requirements=['wheel'])
    File "/tmp/pip-build-env-csmolp15/overlay/lib/python3.8/site-packages/setuptools/build_meta.py", line 295, in _get_build_requires
      self.run_setup()
    File "/tmp/pip-build-env-csmolp15/overlay/lib/python3.8/site-packages/setuptools/build_meta.py", line 311, in run_setup
      exec(code, locals())
    File "<string>", line 155, in <module>
    File "<string>", line 49, in get_config_posix
    File "<string>", line 28, in find_package_name
  Exception: Can not find valid pkg-config name.
  Specify MYSQLCLIENT_CFLAGS and MYSQLCLIENT_LDFLAGS env vars manually
  ----------------------------------------
ERROR: Command errored out with exit status 1: '/home/kanishka/Documents/Ceylone Soft/bcj_dev_back_end/BuyChem/bin/python3' /tmp/tmp81chy8bh get_requires_for_build_wheel /tmp/tmpbjs9srac Check the logs for full command output.

解决步骤 #

1. 安装系统依赖（优先推荐） #

错误核心是缺少MySQL/MariaDB开发库和pkg-config工具，先安装对应系统的依赖包：

Ubuntu/Debian 系列

sudo apt-get update
sudo apt-get install python3-dev default-libmysqlclient-dev pkg-config

CentOS/RHEL 系列

sudo yum install python3-devel mysql-devel pkgconfig

Fedora

sudo dnf install python3-devel mysql-devel pkgconf

安装完依赖后，重新执行：

pip install mysqlclient

2. 手动指定环境变量（如果上述方法无效） #

若系统依赖安装后仍报错，手动获取MySQL编译参数并设置环境变量：

先用pkg-config查找已安装的MySQL/MariaDB库（以libmariadb为例）：

pkg-config --cflags libmariadb
pkg-config --libs libmariadb

将输出结果作为环境变量传入pip命令：

MYSQLCLIENT_CFLAGS="$(pkg-config --cflags libmariadb)" MYSQLCLIENT_LDFLAGS="$(pkg-config --libs libmariadb)" pip install mysqlclient

若找不到对应pkg-config包，可直接指定MySQL安装路径（假设路径为/usr/local/mysql）：

MYSQLCLIENT_CFLAGS="-I/usr/local/mysql/include" MYSQLCLIENT_LDFLAGS="-L/usr/local/mysql/lib -lmysqlclient" pip install mysqlclient

3. 验证安装 #

安装完成后，在Python环境中测试：

import MySQLdb

无报错则说明安装成功。

内容的提问来源于stack exchange，提问作者Kanishka Abeysinghe