An Introduction to Chef
Chef is an automation platform for writing system configurations. It allows dev ops teams to automate the deployment and configuration of shared servers and distributed computing environments. In this article, we explore what Chef is, including how Chef works and the problems it solves.
What is Chef?
Chef is a platform for automating infrastructure. In a nutshell, Chef transforms infrastructure to code. It exemplifies the idea behind Infrastructure as Code (IAC) where code is written to automate the management and provisioning of system infrastructure. Chef uses a domain specific language (Ruby) for defining system configuration in a centralized, easily readable, and reusable format.
The Problem Chef Solves:
Operations teams typically manage a cluster of servers having different environments. While bash scripting and manual deploys are one way to manage this system, things become increasingly difficult with the addition of each new server or environment added. DevOps engineers often find themselves implementing the same configuration over and over again with these more traditional approaches.
Chef solves this problem with a centralized source for all system configuration. Using Chef, engineers can easily define and implement different configurations for different environments. Servers can then be automatically configured and provisioned based on the same set of rules defined in Chef. This makes it possible to scale without the need for more manual deploys.
Chef provides an accurate history of previous deployments and configurations that plays well with enterprise analytics and reporting.
Chef also abstracts system configuration with an easily readable language (Ruby). This makes it easy for engineers to understand existing configuration and reduces the amount of documentation needed for environment setups and deployment.
How Chef Works
With a distributed environment, a central chef server acts as a hub for the systems configuration data. Chef clients are then installed on server nodes and communicate with the central chef server to automatically configure and provision the nodes they run on. Since configuration information is stored in a database on the central server, chef clients can query the chef server for configuration details and update themselves as necessary.
Below is a list and short description of the major components used with Chef:
Work station
The work station is the portal through which users create and test recipes and cookbooks.
Recipe
A recipe is the smallest unit of configuration in Chef. It describes things like packages to be installed, services to run, and files to write for a particular state or environment.
Cookbook
Recipes are grouped into cookbooks. These cookbooks define and execute scenarios such as installing applications and provisioning servers.
Node
Any server that runs a chef client. Nodes pull down configuration data from the central chef server as needed via the chef client installed on that node.
Chef Client
The agent that runs locally on a chef managed server node to pull configuration data from the central chef server.
Chef Server
The central server that defines and stores all relevant configuration data. Chef clients pull data from the central chef server.
Chef Management Console
The user interface for managing/interacting with Chef. Using the Chef management console, users can easily manage cookbook, environments, data bags, etc.
To recap, users author and test recipes on work stations. These recipes are grouped into cookbooks for easier management. Chef clients run on server nodes that pull configuration data from the central chef server. This brings scalability to system configuration as server nodes can update themselves dynamically based on a centralized configuration. Server nodes can run cookbooks via the chef client locally and manage their own provisioning.
Conclusion
Chef greatly improves devOps by providing a clear abstraction for system configuration. Using Chef, developers can easily define configurations for different environments that scale with additional servers. Chef implements the ideas behind infrastructure as code.
