Chef Fundamentals

Chef is a configuration management tool that defines infrastructure as Ruby-based code called recipes and cookbooks. It converges systems toward a declared desired state, ensuring consistent configuration across servers whether they number ten or ten thousand.

itInfrastructure and operations

Chef Fundamentals

Chef Infra manages system configuration as code. You describe the state a node should have, and Chef Infra Client moves that node toward the described state. A package should be installed. A file should contain approved content. A service should be enabled and running.

The central idea is convergence. Chef Infra Client compares each resource declaration with the current node. It changes the node only when the declared state is not already present. Repeated runs should reach the same final state without repeating unnecessary work.

Chef is useful when you manage many long-lived systems that must follow consistent policy. It gives configuration changes the same review, testing, and version-control practices as application code. It can also correct configuration drift during later runs.

The operating model

A typical Chef Infra installation has three main parts:

Chef Workstation is where you author and test policy.
Chef Infra Server stores cookbooks, policies, and node metadata.
Chef Infra Client runs on managed nodes and applies policy locally.

A managed system is a node. During a client run, Chef Infra Client collects node details with Ohai, authenticates to Chef Infra Server, and retrieves its policy. It then compiles a resource collection and converges the node.

The pull model matters. Nodes normally contact Chef Infra Server on a schedule. The server distributes policy, but the client performs most configuration work on the node. A temporary network interruption can delay retrieval without changing the policy already assigned to that node.

Chef Fundamentals

The operating model

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