Kubernetes and Cloud Native Associate (KCNA): key terms

Flashcards for this exam Kubernetes and Cloud Native Associate (KCNA) guide

• Admission ControllerA Kubernetes API server plugin that intercepts requests after authentication and authorization to validate or mutate objects before persistence.Advanced
• AlertmanagerThe Prometheus component that deduplicates, groups, routes, silences, and inhibits alerts and sends notifications.Intermediate
• Argo CDA declarative GitOps continuous delivery tool for Kubernetes that syncs cluster state with manifests stored in Git.Intermediate
• BackstageAn open-source CNCF framework, originally from Spotify, for building developer portals with a software catalog, templates, and plugins.Intermediate
• Canary DeploymentReleasing a new model to a small fraction of traffic first, then increasing gradually if metrics are healthy.Intermediate
• CardinalityIn observability, the number of unique time series created by the combinations of metric label values.Advanced
• Cluster AutoscalerA Kubernetes component that adds nodes when pods cannot be scheduled and removes underutilized nodes.Intermediate
• ConfigMapA Kubernetes object that stores non-confidential configuration data as key-value pairs for pods to consume.Foundational
• ContainerA lightweight, isolated runtime environment that packages an application with its dependencies and shares the host operating system kernel.Foundational
• Container ImageAn immutable, layered package containing an application, its runtime, libraries, and configuration, used to create containers.Foundational
• Container Network Interface (CNI)A CNCF specification and plugin model for configuring network interfaces for containers, used by Kubernetes for pod networking.Intermediate
• Container RegistryA service that stores and distributes container images, such as Docker Hub, Amazon ECR, Azure Container Registry, Google Artifact Registry, Quay, or Harbor.Foundational
• Container RuntimeThe software that runs containers on a host, such as containerd, CRI-O, or the low-level runc.Intermediate
• Container Runtime Interface (CRI)A Kubernetes gRPC API that lets the kubelet use any compliant container runtime.Intermediate
• Container Storage Interface (CSI)A standard API that lets storage vendors write plugins to expose block and file storage to container orchestrators.Advanced
• containerdA CNCF graduated, industry-standard container runtime that manages image transfer, storage, and container execution.Intermediate
• Control Groups (cgroups)A Linux kernel feature that limits, accounts for, and isolates CPU, memory, I/O, and other resources for groups of processes.Advanced
• Control PlaneThe Kubernetes components that manage cluster state: kube-apiserver, etcd, kube-scheduler, kube-controller-manager, and cloud-controller-manager.Foundational
• CoreDNSThe default cluster DNS server in Kubernetes that resolves Service and pod names.Intermediate
• CRI-OA lightweight Kubernetes-specific container runtime implementing the CRI with OCI-compatible runtimes.Intermediate
• Custom Resource Definition (CRD)A Kubernetes API extension that defines a new resource type that can be managed like built-in objects.Advanced
• DaemonSetA Kubernetes workload object that ensures a copy of a pod runs on all (or selected) nodes.Foundational
• Declarative ConfigurationSpecifying the desired end state of a system and letting a tool determine the steps to reach it.Foundational
• DeploymentA Kubernetes workload object that manages ReplicaSets to provide declarative updates, scaling, and rollback for stateless pods.Foundational
• Distributed TracingTracking a single request as it flows across multiple services by propagating a trace context and recording timed spans.Intermediate
• DockerA platform and toolset for building, shipping, and running containers, including Docker Engine, the docker CLI, Docker Compose, and Docker Desktop.Foundational
• DockerfileA text file of instructions (FROM, RUN, COPY, CMD, and others) that Docker uses to build a container image.Foundational
• EnvoyA high-performance CNCF graduated L4/L7 proxy designed for cloud-native applications and used as the data plane of many service meshes.Advanced
• etcdA distributed, consistent key-value store that holds all Kubernetes cluster state.Intermediate
• FluentdAn open-source CNCF graduated log collector that unifies log collection, parsing, buffering, and routing to many outputs.Intermediate
• FluxA CNCF graduated GitOps toolkit that keeps Kubernetes clusters in sync with configuration sources such as Git repositories and OCI artifacts.Intermediate
• Four Golden SignalsThe four key metrics Google SRE recommends monitoring for any user-facing system: latency, traffic, errors, and saturation.Foundational
• Gateway APIThe Kubernetes successor to Ingress providing role-oriented, extensible resources such as GatewayClass, Gateway, and HTTPRoute.Advanced
• GitOpsAn operating model where desired infrastructure and app state is stored declaratively in Git and automatically reconciled to the live environment.Intermediate
• GrafanaAn open-source visualization and dashboarding platform that queries data sources such as Prometheus, Loki, Elasticsearch, and cloud monitoring services.Foundational
• gRPCA high-performance open-source RPC framework that uses HTTP/2 transport and Protocol Buffers serialization.Intermediate
• HelmThe package manager for Kubernetes that templates, installs, upgrades, and rolls back applications packaged as charts.Intermediate
• Helm ChartA Helm package containing Chart.yaml, values.yaml, and Go-templated Kubernetes manifests in a templates directory.Intermediate
• Horizontal Pod Autoscaler (HPA)A Kubernetes controller that scales the number of pod replicas based on CPU, memory, or custom metrics.Intermediate
• IngressA Kubernetes API object that manages external HTTP/HTTPS access to Services with host- and path-based routing and TLS termination.Intermediate
• Ingress ControllerA component running in the cluster that implements Ingress rules by configuring a reverse proxy or cloud load balancer.Intermediate
• Init ContainerA container in a pod that runs to completion before the app containers start, used for setup tasks.Intermediate
• IstioA CNCF graduated open-source service mesh using Envoy proxies to provide traffic management, security, and observability.Advanced
• JaegerAn open-source CNCF graduated distributed tracing platform for collecting, storing, and visualizing traces.Intermediate
• kube-apiserverThe Kubernetes component that exposes the REST API and is the front end and only component that talks directly to etcd.Intermediate
• kube-controller-managerThe control plane component that runs core controllers such as the Deployment, ReplicaSet, Node, and Job controllers.Intermediate
• kube-proxyA node component that maintains network rules (iptables, IPVS, or nftables) to implement Kubernetes Service virtual IPs.Advanced
• kube-schedulerThe control plane component that assigns newly created pods to suitable nodes.Intermediate
• kubeconfigA YAML file that stores cluster endpoints, user credentials, and contexts used by kubectl.Foundational
• kubectlThe Kubernetes command-line tool for interacting with the API server to create, inspect, update, and delete resources.Foundational
• kubeletThe node agent that ensures containers described in PodSpecs are running and healthy on each Kubernetes node.Intermediate
• Kubernetes (K8s)An open-source CNCF container orchestration platform that automates deployment, scaling, networking, and self-healing of containerized applications.Foundational
• Kubernetes JobA Kubernetes workload that runs pods to completion for batch tasks, retrying failures up to a backoff limit.Intermediate
• Kubernetes SecretA Kubernetes object for storing small amounts of sensitive data such as passwords, tokens, and TLS keys.Foundational
• KustomizeA template-free tool, built into kubectl, that customizes Kubernetes YAML using bases, overlays, and patches.Intermediate
• Label and SelectorKey-value pairs attached to Kubernetes objects (labels) and the queries that match them (selectors).Foundational
• LinkerdA lightweight CNCF graduated service mesh that uses its own Rust-based micro-proxy to add mTLS, reliability, and observability.Advanced
• Linux NamespacesA Linux kernel feature that isolates process views of system resources such as PIDs, network, mounts, users, IPC, and hostnames.Advanced
• Liveness ProbeA Kubernetes health check that restarts a container when it fails, indicating the container is unhealthy or stuck.Intermediate
• Local Kubernetes ClusterA single-machine Kubernetes environment for development and testing, such as minikube, kind, k3d, or Docker Desktop Kubernetes.Foundational
• Log AggregationCollecting logs from many systems into a central store for search, correlation, retention, and alerting.Foundational
• ManifestA YAML or JSON file describing Kubernetes objects with apiVersion, kind, metadata, and spec fields.Foundational
• Metric TypesThe kinds of metrics used in monitoring systems such as Prometheus: counter, gauge, histogram, and summary.Intermediate
• Microservices ArchitectureAn architectural style that structures an application as small, independently deployable services communicating over APIs.Foundational
• Mutual TLS (mTLS)TLS in which both client and server present and verify certificates, providing two-way authentication and encryption.Intermediate
• NamespaceA Kubernetes mechanism for dividing a cluster into virtual partitions that scope names, policies, quotas, and access control.Foundational
• Network PolicyA Kubernetes resource that controls allowed ingress and egress traffic for selected pods at the IP and port level.Intermediate
• NodeA worker machine, virtual or physical, in a Kubernetes cluster that runs pods.Foundational
• ObservabilityThe ability to understand a system's internal state from its external outputs, typically metrics, logs, and traces.Foundational
• Open Container Initiative (OCI)A Linux Foundation project defining open standards for container image format, runtime, and distribution.Intermediate
• Open Policy Agent (OPA)A CNCF graduated general-purpose policy engine that evaluates policies written in Rego against JSON input.Advanced
• OpenTelemetry (OTel)A CNCF open standard and set of SDKs, APIs, and a collector for generating and exporting metrics, logs, and traces vendor-neutrally.Intermediate
• OpenTelemetry CollectorA vendor-agnostic agent or gateway that receives, processes, and exports telemetry data using pipelines of receivers, processors, and exporters.Advanced
• OperatorA Kubernetes extension that uses custom resources and a controller to automate the lifecycle of complex applications.Advanced
• Operator Lifecycle Manager (OLM)A component that installs, updates, and manages the lifecycle of Kubernetes operators, central to OpenShift.Advanced
• Persistent Volume (PV)A cluster-scoped Kubernetes storage resource provisioned by an administrator or dynamically by a StorageClass.Intermediate
• Persistent Volume Claim (PVC)A namespaced request for storage by a user that binds to a matching PersistentVolume.Intermediate
• Pets vs CattleAn analogy contrasting uniquely cared-for servers (pets) with interchangeable, replaceable servers (cattle).Foundational
• PodThe smallest deployable unit in Kubernetes: one or more containers sharing network namespace, storage volumes, and a lifecycle.Foundational
• Progressive DeliveryAn evolution of continuous delivery that releases changes gradually with automated analysis, using canaries, feature flags, and traffic shaping.Advanced
• PrometheusAn open-source CNCF graduated monitoring system and time-series database that scrapes metrics over HTTP and supports alerting with PromQL.Intermediate
• Prometheus ExporterA process that exposes metrics from a third-party system in Prometheus format on an HTTP endpoint.Intermediate
• PromQLThe Prometheus Query Language used to select, aggregate, and compute on time-series metrics.Advanced
• PushgatewayA Prometheus component that lets short-lived or batch jobs push metrics so Prometheus can scrape them later.Advanced
• Readiness ProbeA Kubernetes check that determines whether a pod can receive traffic; failing pods are removed from Service endpoints.Intermediate
• Reconciliation LoopThe control-loop pattern in which a controller repeatedly compares desired state with actual state and acts to close the gap.Intermediate
• Red Hat OpenShiftRed Hat's enterprise Kubernetes platform that adds integrated developer tools, security defaults, operators, and a web console.Intermediate
• ReplicaSetA Kubernetes controller that maintains a stable set of identical pod replicas.Foundational
• Resource Requests and LimitsKubernetes settings that declare the minimum CPU/memory a container needs (requests) and the maximum it may use (limits).Intermediate
• Role-Based Access Control (RBAC)The Kubernetes authorization mode that grants permissions through Roles/ClusterRoles bound to users, groups, or service accounts.Intermediate
• Rolling DeploymentA release strategy that gradually replaces instances of the old version with the new version in batches.Foundational
• ServiceA Kubernetes object that provides a stable virtual IP and DNS name to load balance traffic to a set of pods selected by labels.Foundational
• Service MeshAn infrastructure layer that manages service-to-service communication with traffic management, mTLS security, and observability, usually via proxies.Intermediate
• Service TypesThe Kubernetes Service exposure modes: ClusterIP, NodePort, LoadBalancer, and ExternalName.Foundational
• Sidecar ContainerA helper container that runs alongside the main application container in the same pod to extend its functionality.Intermediate
• StatefulSetA Kubernetes workload object for stateful applications that need stable network identities, ordered deployment, and persistent storage per pod.Intermediate
• Taints and TolerationsA Kubernetes mechanism where node taints repel pods unless the pods have matching tolerations.Intermediate
• TektonA Kubernetes-native open-source framework for building CI/CD pipelines using custom resources such as Task and Pipeline.Advanced
• Three Pillars of ObservabilityThe three primary telemetry types used for observability: metrics, logs, and traces.Foundational
• Vertical Pod Autoscaler (VPA)A Kubernetes add-on that recommends or automatically adjusts container CPU and memory requests based on usage.Advanced