Kubernetes (container orchestrator)

Kubernetes (container orchestrator)
Name	Kubernetes
Developer	Google; Cloud Native Computing Foundation
Initial release	2014
Latest release	(varies)
Repo	kubernetes/kubernetes
Written in	Go
Operating system	Linux; Windows
License	Apache License 2.0

Kubernetes (container orchestrator) Kubernetes is an open-source container orchestration system for automating deployment, scaling, and management of containerized applications. It originated from work at Google and is now maintained by the Cloud Native Computing Foundation, with contributions from entities such as Red Hat, VMware, Microsoft, Amazon Web Services, IBM, and Canonical. Kubernetes coordinates workloads across clusters of machines, integrating with projects and products from organizations like Docker, CoreOS, Heptio, HashiCorp, CNCF, and Mesosphere.

Overview

Kubernetes provides primitives for deploying distributed systems modeled after patterns used at Google in systems like Borg and Omega. The project combines ideas implemented by companies including Amazon Web Services, Microsoft Azure, Google Cloud Platform, and IBM Cloud with tools from the Linux Foundation ecosystem. The platform integrates with container runtimes such as Docker Engine, containerd, CRI-O, and orchestration alternatives like Apache Mesos and HashiCorp Nomad. End-user tooling and management are provided by vendors including Red Hat OpenShift, Rancher Labs, Pivotal, SUSE, and cloud-native services from Google Kubernetes Engine, Amazon EKS, Azure Kubernetes Service, and IBM Cloud Kubernetes Service.

Architecture

Kubernetes implements a distributed control plane architecture inspired by Borg and Omega with components that run on master and node hosts. The control plane includes the kube-apiserver, etcd as a key-value store, the kube-scheduler, and controllers like the kube-controller-manager. Worker nodes run agents such as the kubelet and network proxies such as kube-proxy. Kubernetes interfaces with operating systems like Ubuntu, Red Hat Enterprise Linux, CentOS, Debian, and CoreOS Container Linux and supports orchestration across virtualized infrastructure from VMware vSphere, OpenStack, Google Compute Engine, and Amazon EC2. High-availability deployments, role-based access control from OpenID Connect and OAuth 2.0, and service discovery patterns reflect practices adopted by enterprises like Salesforce, LinkedIn, Spotify, and Airbnb.

Core Concepts and Components

Key abstractions include Pod, ReplicaSet, Deployment, StatefulSet, DaemonSet, Job, and CronJob, which manage lifecycle and scaling. Networking constructs include Service and Ingress resources with implementations such as NGINX Ingress Controller, Traefik, Istio, Linkerd, and Ambassador API Gateway. Storage is provisioned via PersistentVolume and PersistentVolumeClaim with dynamic provisioning supported by Container Storage Interface drivers from vendors like NetApp, Ceph, Portworx, Rook, and GlusterFS. Configuration and secret management use ConfigMap and Secret, integrating with vaults such as HashiCorp Vault, AWS Secrets Manager, Azure Key Vault, and Google Secret Manager. Observability is achieved through integrations with Prometheus, Grafana, Jaeger, Zipkin, Elasticsearch, Fluentd, and Kibana. Authentication, authorization, and auditing involve RBAC, Open Policy Agent, Istio RBAC, and identity providers such as Okta and Active Directory.

Deployment and Operations

Kubernetes supports continuous delivery workflows with tools like Helm, Kustomize, Argo CD, Flux, and CI/CD platforms including Jenkins, GitLab CI, CircleCI, Travis CI, TeamCity, and Azure DevOps. Cluster lifecycle management is handled by projects and tools such as kubeadm, kops, Kubermatic, Rancher, Google Anthos, AWS CloudFormation, and Terraform from HashiCorp. Operators pattern orchestration is implemented with Operator Framework and projects like Prometheus Operator, Etcd Operator, MongoDB Kubernetes Operator, and Postgres Operator. Backup and disaster recovery integrate with Velero, Restic, and commercial offerings from Veeam and Portworx. Service mesh adoption drives day-two operations with Istio, Consul, and Linkerd affecting traffic management, observability, and security.

Networking, Storage, and Security

Networking in Kubernetes uses Container Network Interface plugins such as Calico, Flannel, Weave Net, Cilium, and Canal to implement pod networking, network policies, and load balancing. Storage solutions span cloud-native block and file systems offered by Amazon EBS, Google Persistent Disk, Azure Disk, and distributed systems like Ceph, GlusterFS, NFS, and OpenEBS. Security posture leverages tools and standards including AppArmor, SELinux, seccomp, Pod Security Policies (deprecated in favor of Pod Security Admission), NetworkPolicy, and supply-chain protections like in-toto, sigstore, Notary, and TUF. Image signing and vulnerability scanning are provided by Clair, Trivy, Anchore, Twistlock (now part of Palo Alto Networks), and cloud offerings from Google Cloud Security Command Center and AWS Security Hub.

Ecosystem and Integrations

The Kubernetes ecosystem encompasses a broad array of projects hosted by the Cloud Native Computing Foundation and other organizations: Prometheus, Envoy, gRPC, OpenTelemetry, Harbor, Knative, Open Policy Agent, Service Mesh Interface, Container Storage Interface, CRI-O, containerd, Buildpacks, Tekton, Backstage, KubeVirt, MetalLB, Longhorn, Flux CD, Argo Workflows, KEDA, Knative Serving, and Skaffold. Major cloud providers and vendors such as Google Cloud, Amazon Web Services, Microsoft, IBM, Red Hat, VMware, Cisco, Intel, NVIDIA, Dell, and HPE build managed services and integrations. Enterprises and open-source projects from Spotify, Airbnb, Pinterest, Shopify, Netflix, Uber, Salesforce, Dropbox, and eBay contribute operation patterns, tooling, and case studies.

History and Development

Kubernetes was announced by Google in 2014 and donated to the Cloud Native Computing Foundation to foster open governance modeled after projects like Linux Kernel and Apache HTTP Server. Key milestones include the initial open-source release, adoption of Docker containers, the formation of working groups within the CNCF, and the emergence of distributions and managed services from Red Hat, VMware, Google, Amazon Web Services, and Microsoft. Influential figures and organizations involved in the project include engineers and leaders from Google and contributors associated with Heptio founders who later joined VMware, and corporate backers such as IBM and Huawei. Kubernetes’ evolution has been shaped by standards and adjacent projects like Open Container Initiative, Cloud Foundry, and research on cluster schedulers exemplified by Borg and Omega.

Category:Cloud computing