YML标准没有指定这样做的方法。而且这个问题并不局限于YML。JSON也有同样的限制。

许多使用基于YML或JSON配置的应用程序最终都会遇到这个问题。当这种情况发生时，他们就会制定自己的惯例。

例如，对于swagger API定义:

$ref: 'file.yml'

例如，对于docker组合配置:

services:
  app:
    extends:
      file: docker-compose.base.yml

或者，如果您希望将一个yml文件的内容拆分到多个文件中，就像内容树一样，您可以定义自己的文件夹结构约定并使用(现有的)合并脚本。

根据之前的帖子:

  class SimYamlLoader(yaml.SafeLoader):
        '''
        Simple custom yaml loader that supports include, e.g:

        main.yaml:

        - !include file1.yaml
        - !include dir/file2.yaml

        '''

        def __init__(self, stream):
            self.root = os.path.split(stream.name)[0]
            super().__init__(stream)

    def _include(loader, node):
        filename = os.path.join(loader.root, loader.construct_scalar(node))
        with open(filename, 'r') as f:
            return yaml.load(f, SimYamlLoader)
    SimYamlLoader.add_constructor('!include', _include)

    # example:
    with open('main.yaml', 'r') as f:
        lists = yaml.load(f, SimYamlLoader)
        # if you want to merge the lists
        data = functools.reduce(
            lambda x, y: x if y is None else {**x, **dict(y)}, lists, {})
        # python 3.10+:lambda x, y: x if y is None else x | dict(y), lists, {})

我举了一些例子供你参考。

import yaml

main_yaml = """
Package:
 - !include _shape_yaml    
 - !include _path_yaml
"""

_shape_yaml = """
# Define
Rectangle: &id_Rectangle
    name: Rectangle
    width: &Rectangle_width 20
    height: &Rectangle_height 10
    area: !product [*Rectangle_width, *Rectangle_height]

Circle: &id_Circle
    name: Circle
    radius: &Circle_radius 5
    area: !product [*Circle_radius, *Circle_radius, pi]

# Setting
Shape:
    property: *id_Rectangle
    color: red
"""

_path_yaml = """
# Define
Root: &BASE /path/src/

Paths: 
    a: &id_path_a !join [*BASE, a]
    b: &id_path_b !join [*BASE, b]

# Setting
Path:
    input_file: *id_path_a
"""


# define custom tag handler
def yaml_import(loader, node):
    other_yaml_file = loader.construct_scalar(node)
    return yaml.load(eval(other_yaml_file), Loader=yaml.SafeLoader)


def yaml_product(loader, node):
    import math
    list_data = loader.construct_sequence(node)
    result = 1
    pi = math.pi
    for val in list_data:
        result *= eval(val) if isinstance(val, str) else val
    return result


def yaml_join(loader, node):
    seq = loader.construct_sequence(node)
    return ''.join([str(i) for i in seq])


def yaml_ref(loader, node):
    ref = loader.construct_sequence(node)
    return ref[0]


def yaml_dict_ref(loader: yaml.loader.SafeLoader, node):
    dict_data, key, const_value = loader.construct_sequence(node)
    return dict_data[key] + str(const_value)


def main():
    # register the tag handler
    yaml.SafeLoader.add_constructor(tag='!include', constructor=yaml_import)
    yaml.SafeLoader.add_constructor(tag='!product', constructor=yaml_product)
    yaml.SafeLoader.add_constructor(tag='!join', constructor=yaml_join)
    yaml.SafeLoader.add_constructor(tag='!ref', constructor=yaml_ref)
    yaml.SafeLoader.add_constructor(tag='!dict_ref', constructor=yaml_dict_ref)

    config = yaml.load(main_yaml, Loader=yaml.SafeLoader)

    pk_shape, pk_path = config['Package']
    pk_shape, pk_path = pk_shape['Shape'], pk_path['Path']
    print(f"shape name: {pk_shape['property']['name']}")
    print(f"shape area: {pk_shape['property']['area']}")
    print(f"shape color: {pk_shape['color']}")

    print(f"input file: {pk_path['input_file']}")


if __name__ == '__main__':
    main()

输出

shape name: Rectangle
shape area: 200
shape color: red
input file: /path/src/a

更新2

你可以把它们结合起来，像这样

# xxx.yaml
CREATE_FONT_PICTURE:
  PROJECTS:
    SUNG: &id_SUNG
      name: SUNG
      work_dir: SUNG
      output_dir: temp
      font_pixel: 24


  DEFINE: &id_define !ref [*id_SUNG]  # you can use config['CREATE_FONT_PICTURE']['DEFINE'][name, work_dir, ... font_pixel]
  AUTO_INIT:
    basename_suffix: !dict_ref [*id_define, name, !product [5, 3, 2]]  # SUNG30

# ↓ This is not correct.
# basename_suffix: !dict_ref [*id_define, name, !product [5, 3, 2]]  # It will build by Deep-level. id_define is Deep-level: 2. So you must put it after 2. otherwise, it can't refer to the correct value.

不幸的是，YAML在其标准中没有提供这个功能。

但是如果你正在使用Ruby，有一个gem通过扩展Ruby YAML库来提供你所要求的功能: https://github.com/entwanderer/yaml_extend

使用Symfony，它对yaml的处理将间接地允许您嵌套yaml文件。诀窍在于使用参数选项。例如:

common.yml

parameters:
    yaml_to_repeat:
        option: "value"
        foo:
            - "bar"
            - "baz"

config.yml

imports:
    - { resource: common.yml }
whatever:
    thing: "%yaml_to_repeat%"
    other_thing: "%yaml_to_repeat%"

其结果将与:

whatever:
    thing:
        option: "value"
        foo:
            - "bar"
            - "baz"
    other_thing:
        option: "value"
        foo:
            - "bar"
            - "baz"

使用Yglu，你可以像这样导入其他文件:

A.yaml

foo: !? $import('B.yaml')

B.yaml

bar: Hello

$ yglu A.yaml
foo:
  bar: Hello

因为$import是一个函数，你也可以传递一个表达式作为参数:

  dep: !- b
  foo: !? $import($_.dep.toUpper() + '.yaml')

这将得到与上面相同的输出。

声明:我是Yglu的作者。