Kubernetes Glossary
- Centralized Terminology: This glossary provides a comprehensive reference for common Kubernetes terms and concepts.
- Quick Definitions: Each entry offers a concise explanation and often includes links to official documentation for deeper understanding.
- Foundation for Learning: Familiarity with these terms is crucial for understanding Kubernetes architecture and functionality.
A comprehensive list of Kubernetes terminology with links to official documentation.
A-C
Cluster
A set of worker machines, called Nodes, that run containerized applications. Every cluster has at least one worker node.
ConfigMap
An API object used to store non-confidential data in key-value pairs. Pods can consume ConfigMaps as environment variables, command-line arguments, or as configuration files in a volume.
Container
A lightweight and portable executable image that contains software and all of its dependencies. Kubernetes is an orchestrator for containers.
Control Plane
The container orchestration layer that exposes the API and interfaces to define, deploy, and manage the lifecycle of containers. It consists of the API Server, etcd, Scheduler, and Controller Manager.
CronJob
A controller that runs Jobs on a repeating schedule (like a Linux cron tab).
D-H
DaemonSet
A workload that ensures a copy of a Pod is running on every node in the cluster (or a specific subset of nodes).
Deployment
An API object that manages a replicated application, typically by running Pods with no local state. It provides declarative updates (Rolling Updates) for Pods and ReplicaSets.
etcd
A consistent and highly-available key-value store used as the backing store for all cluster data.
Helm
The package manager for Kubernetes. It helps you manage Kubernetes applications via "Charts".
HPA (Horizontal Pod Autoscaler)
Automatically updates a workload resource (such as a Deployment or StatefulSet), with the aim of automatically scaling the workload to match demand.
I-L
Ingress
An API object that manages external access to the services in a cluster, typically HTTP. Ingress may provide load balancing, SSL termination, and name-based virtual hosting.
Job
A workload that creates one or more Pods and ensures that a specified number of them successfully terminate.
Kubelet
An agent that runs on each node in the cluster. It makes sure that containers are running in a Pod.
Kubectl
The command line tool for communicating with the Kubernetes API server.
Label
Key/value pairs that are attached to objects, such as Pods. Labels are intended to be used to specify identifying attributes of objects that are meaningful to users.
Liveness Probe
A health check that tells Kubernetes if a container is running. If it fails, the container is killed and restarted.
M-P
Namespace
An abstraction used by Kubernetes to support multiple virtual clusters on the same physical cluster. Namespaces are widely used in environments with many users spread across multiple teams.
Node
A worker machine in Kubernetes. A node may be a VM or physical machine, depending on the cluster.
Network Policy
An API object that lets you control the traffic flow at the IP address or port level (Layer 3 or 4) between Pods.
Persistent Volume (PV)
A piece of storage in the cluster that has been provisioned by an administrator or dynamically provisioned using Storage Classes.
Persistent Volume Claim (PVC)
A request for storage by a user. It is similar to a Pod. Pods consume node resources and PVCs consume PV resources.
Pod
The smallest and simplest Kubernetes object. A Pod represents a set of running containers on your cluster.
R-S
Readiness Probe
A health check that tells Kubernetes if a container is ready to accept traffic. If it fails, the Pod is removed from Service endpoints.
ReplicaSet
A purpose of the ReplicaSet is to maintain a stable set of replica Pods running at any given time.
Secret
An object that contains a small amount of sensitive data such as a password, a token, or a key.
Selector
Allows users to filter a list of resources based on Labels.
Service
An abstract way to expose an application running on a set of Pods as a network service.
Sidecar
A pattern where a secondary container runs alongside the main application container in the same Pod (e.g., logging agents, service mesh proxies).
StatefulSet
A workload API object used to manage stateful applications. It manages the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods.
T-Z
Taint / Toleration
Taints allow a node to repel a set of pods. Tolerations are applied to pods, and allow (but do not require) the pods to schedule onto nodes with matching taints.
Volume
A directory, possibly with some data in it, which is accessible to the containers in a Pod.