Creating functional roles

Until now, we have created cookbooks based on a particular technology. We created a cookbook for MariaDB, one for Apache HTTPd, and one for our app (including all the dependencies). What about the role of each of those infrastructure elements? A database role can include what is now running our database (MariaDB), but maybe tomorrow it can run something else (migrate back to MySQL, or switch to PostgreSQL). As roles in Chef have a dedicated run list, it's common to see a role include the product recipes, and everything related to it, think monitoring for example. Roles can do a lot more, like overriding attributes or have different run lists for each environment. Here, we'll create two generic database and webserver roles that might be simply reused later for another project that just need those services and a mysite role, that will include the two other roles. A role can include other roles as well as recipes. This way, the role for mysite will be enough to run...