Kubernetes Core Objects Cheatsheet

A Pod is the smallest deployable unit in Kubernetes; it encapsulates one or more tightly coupled containers that share a network namespace, IPC, and optionally volumes.

A Pod represents a single instance of a running process in a cluster and is described by a Pod manifest containing metadata (labels, annotations) and a pod spec.

A ReplicaSet manages a stable set of identical Pods and ensures a specified number of pod replicas are running at any given time.

A Deployment, which manages a ReplicaSet and provides declarative updates, rolling updates, and rollback capability.

A StatefulSet manages the deployment and scaling of a set of Pods with stable, unique network identities and persistent per-pod storage.

Choose a StatefulSet when Pods need stable network IDs, stable persistent storage, or ordered, graceful deployment and scaling (e.g., databases, message brokers).

A DaemonSet ensures that a copy of a Pod runs on all (or a subset of) nodes, typically used for node-level agents like log shippers, monitoring, or CNI plugins.

A Job runs one or more Pods to perform a batch task to completion, tracking successful completions and supporting parallel execution.

A CronJob manages time-scheduled Jobs by creating Job objects on a cron schedule, similar to Unix crontab entries.

A Job runs once and finishes; a CronJob creates Jobs on a schedule and manages their lifecycle, including concurrency policy and history limits.

A Service is an abstraction that defines a logical set of Pods and a policy to access them, usually via a stable virtual IP and DNS name.

A Service uses a label selector to dynamically route traffic to Pods whose labels match; endpoints are updated automatically by the endpoints controller.