运行molecule create命令时出现KeyError: 'docker'错误求助

问题描述 #

作为Molecule新手，修改了molecule文件夹下的molecule.yml配置文件，内容如下：

---
dependency:
  name: galaxy
driver:
  name: docker
lint:
  name: yamllint
platforms:
  - name: instance
    image: centos:7
    pre_build_image: true
provisioner:
  name: ansible
verifier:
  name: ansible

在Mac和Ubuntu系统中重新部署Molecule后，运行molecule create命令仍出现相同错误，错误栈如下：

Traceback (most recent call last):
  File "/usr/local/bin/molecule", line 8, in <module>
    sys.exit(main())
  File "/usr/lib/python3/dist-packages/click/core.py", line 1128, in __call__
    return self.main(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/click/core.py", line 1053, in main
    rv = self.invoke(ctx)
  File "/usr/lib/python3/dist-packages/click/core.py", line 1659, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/lib/python3/dist-packages/click/core.py", line 1395, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/lib/python3/dist-packages/click/core.py", line 754, in invoke
    return __callback(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/click/decorators.py", line 26, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/usr/local/lib/python3.10/dist-packages/molecule/command/reset.py", line 46, in reset
    base.execute_cmdline_scenarios(scenario_name, args, command_args)
  File "/usr/local/lib/python3.10/dist-packages/molecule/command/base.py", line 94, in execute_cmdline_scenarios
    get_configs(args, command_args, ansible_args, glob_str),
  File "/usr/local/lib/python3.10/dist-packages/molecule/command/base.py", line 185, in get_configs
    configs = [
  File "/usr/local/lib/python3.10/dist-packages/molecule/command/base.py", line 186, in <listcomp>
    config.Config(
  File "/usr/local/lib/python3.10/dist-packages/molecule/config.py", line 64, in __call__
    obj.after_init()
  File "/usr/local/lib/python3.10/dist-packages/molecule/config.py", line 116, in after_init
    self.config = self._reget_config()
  File "/usr/local/lib/python3.10/dist-packages/molecule/config.py", line 308, in _reget_config
    env = util.merge_dicts(os.environ, self.env)
  File "/usr/local/lib/python3.10/dist-packages/molecule/config.py", line 201, in env
    "MOLECULE_INSTANCE_CONFIG": self.driver.instance_config,
  File "/usr/lib/python3.10/functools.py", line 981, in __get__
    val = self.func(instance)
  File "/usr/local/lib/python3.10/dist-packages/molecule/config.py", line 185, in driver
    driver = api.drivers(config=self)[driver_name]
  File "/usr/local/lib/python3.10/dist-packages/molecule/api.py", line 29, in __getitem__
    return self.__dict__[i]
KeyError: 'docker'

解决方案 #

这个错误的核心原因是Molecule的Docker驱动未安装——Molecule核心包不包含Docker驱动，需要单独安装对应的插件：

• 安装Molecule Docker驱动
  执行以下命令安装：

  pip install molecule-docker
  

  如果使用Python虚拟环境，请确保在对应的虚拟环境中执行该命令。

• 验证驱动安装
  安装完成后，运行以下命令查看已安装的驱动：

  molecule drivers
  

  输出中应包含docker，说明驱动已成功加载。

• 重新运行命令
  回到Molecule项目目录，再次执行：

  molecule create
  

  此时应该可以正常创建Docker实例。

补充说明 #

如果使用pipx安装Molecule，需要用pipx inject命令添加驱动：

pipx inject molecule molecule-docker

同时确保系统中已安装并运行Docker服务，否则即使驱动安装成功，也会出现其他连接错误。

内容的提问来源于stack exchange，提问作者Eric27710