Config coding std

Drupal 9 uses YAML files for configuration management.

Introductory notes on the configuration API -

The file name for a configuration object is equal to the unique name of the configuration, with a '.yml' extension.
Each configuration file has a specific structure, which is expressed as a YAML-based configuration schema.
Configuration object can be retrieved by calling

$config = \Drupal::config('mymodule.foo');

and

$value = $config->get('top_level.next_level.another_level');

etc. to get the values from the configuration object.

The configuration file name is equal to the unique configuration name with .yml extension.
The unique configuration name cannot exceed 250 characters.

For simple configuration, the unique configuration name must start with the extension name. Ex - mymodule.settings or mymodule.features

For configuration entities, the unique configuration name has a prefix, which is equal to (extension).(config_prefix).
Here, (extension) is the machine name of the module that defines the config entity, or "core" for core entities
(config_prefix) is defined in the entity annotation, and defaults to the machine name (ID) of the config entity if it has not been overridden by a config_prefix annotation in the entity class.
Extension names cannot exceed 50 characters, and config entity config prefixes cannot exceed 32 characters.
The rest of the unique configuration name for a config entity (which is called the suffix in the rest of this section) is limited to 150 characters.
For many configuration entities, the suffix consists solely of the individual machine name of the item. Ex- the unique configuration name for an image style is image.style.(machine_name_of_style), and for a view it is views.view.(machine_name_of_view)

Config files use YAML syntax and .yml extension.

Comments are not typically in config files, but can be made using #.

Use two spaces to indent in config files. In YAML, the white space has semantic meaning to represent nested structures.