An attribute can be defined in a role and then used to override the default settings on a node. When a role is applied during a Chef Infra Client run, these attributes are compared to the attributes that are already present on the node. When the role attributes take precedence over the default attributes, Chef Infra Client applies those new settings and values during a Chef Infra Client run.
A role attribute can only be set to be a default attribute or an
override attribute. A role attribute cannot be set to be a normal
attribute. Use the default_attribute and override_attribute methods
in the .rb attributes file or the default_attributes and
override_attributes hashes in a JSON data file.