Kubernetes Operators and Crossplane#

The Operator Pattern#

An operator is a CRD (Custom Resource Definition) paired with a controller. The CRD defines a new resource type (like Certificate or KafkaCluster). The controller watches for instances of that CRD and reconciles actual state to match desired state. This is the same reconciliation loop that powers Deployments, extended to anything.

Operators encode operational knowledge into software. Instead of a runbook with 47 steps to create a Kafka cluster, you declare what you want and the operator handles creation, scaling, upgrades, and failure recovery.