User-Defined Roles
MongoDB provides a number of built-in roles. However, if these roles cannot describe the desired set of privileges, you can create new roles.
Role Management Interface
To add a role, MongoDB provides the db.createRole() method.
MongoDB also provides methods to update existing user-defined roles. For
a full list of role management methods, see
Role Management.
Scope
When adding a role, you create the role in a specific database. MongoDB uses the combination of the database and the role name to uniquely define a role.
Except for roles created in the admin database, a role can only
include privileges that apply to its database and can only inherit from
other roles in its database.
A role created in the admin database can include privileges that
apply to the admin database, other databases or to the
cluster resource, and can inherit from roles
in other databases as well as the admin database.
Centralized Role Data
MongoDB stores all role information in the system.roles collection in the admin database
Do not access this collection directly but instead use the role management commands to view and edit custom roles.