Recipes are the core component of getting things done. They are scripts, written in Ruby, that provide the instructions to be executed on end hosts when the Chef client is run. Recipes are placed in the recipes directory inside of a cookbook, and each recipe is designed to achieve a specific purpose, such as provisioning accounts, installing and configuring a database server, and custom software deployments.
Recipes combine configuration data with the current state of the host to execute commands that will cause the system to enter a new state. For example, a PostgreSQL database server recipe would have the goal of installing and starting a PostgreSQL server on any host that runs the recipe. Let's look at a few possible starting states and the expected behavior:
A host without PostgreSQL installed would begin at the state of not having the service; then, it will execute the commands required to install and configure the service
Hosts with an existing but outdated PostgreSQL service...