Kubernetes

Kubernetes (2014) (commonly stylized as K8s[3]) is an open-source Container-Orchestration system for automating deployment, autoscaling (based on CPU, memory or custom metrics) and management of containerized applications.[4] It works with a range of container tools, including Docker.

Kubernetes objects, concepts or subsystems:

• Containers, Pods, Volumes
• Persistent Volumes subsystem provides an API for users and administrators that abstracts details of how storage is provided from how it is consumed
• namespaces

Installation

See: Kubernetes installation and Kubernetes changelog/releases.

Information

• kubeadm version
• kubectl get nodes

Microk8s

MicroK8s single node Kubernetes solution available since December 2018

• Installation:
  • snap install microk8s
  • snap install microk8s --classic

Kubernetes Log files

Master

• /var/log/kube-apiserver.log - API Server, responsible for serving the API
• /var/log/kube-scheduler.log - Scheduler (kube-scheduler), responsible for making scheduling decisions
• /var/log/kube-controller-manager.log - Controller that manages replication controllers
• etcd

Worker Nodes

• /var/log/kubelet.log - Kubelet, responsible for running containers on the node
• /var/log/kube-proxy.log - Kube Proxy, responsible for service load balancing

Kubernetes Ports

• Kubernetes API: TCP 6443
• kubelet listen on port 10250

See also OpenShift port requeriments: https://docs.openshift.com/container-platform/4.2/installing/installing_bare_metal/installing-bare-metal.html

Products

• Red Hat OpenShift
• Red Hat Advanced Cluster Management for Kubernetes
• OKD community distribution
• Canonical Charmed Kubernetes

Activities

• Read Kubernetes changelog/versions: https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG.md
• Read the History of Kubernetes: https://blog.risingstack.com/the-history-of-kubernetes/
• Read wikitech documentation: https://wikitech.wikimedia.org/wiki/Portal:Toolforge/Admin/Kubernetes
• Read Kubernetes Storage documentation: https://kubernetes.io/docs/concepts/storage/ and types of /Volumes/ supported.
• Review Wikipedia Kubernetes Grafana statistics: https://grafana.wikimedia.org/d/G8zPL7-Wz/kubernetes-node?orgId=1&var-dc=eqiad%20prometheus%2Fk8s&var-instance=kubernetes1002.eqiad.wmnet

Kubernetes Cloud Service Providers

Kubernetes is offered as a service on multiple public clouds, including Amazon Web Services (EKS) (since June 2018 in the US East (N. Virginia) and US West (Oregon) Regions), Microsoft Azure (AKS) since october 2017, DigitalOcean (since May 2018), Google Kubernetes Engine (GKE) in Google Cloud Platform (at least since November 2014), IBM Cloud , Alibaba Cloud , Mail.Ru Cloud Solutions (since May 2018) and Oracle Kubernetes Service. For a more comprehensive list you can check https://kubernetes.io/docs/setup/pick-right-solution/#hosted-solutions. Most of them if not all requires a valid credit card.

Kubernetes adoption

• August 16 2017: Github runs on Kubernetes: all web and API requests are served by containers running in Kubernetes clusters deployed on metal cloud.

Related terms

• Helm package manager
• Pod, etcd, Volume, container, Jobs
• Rancher
• Kubernetes operator
• Katacoda
• CoreDNS
• Control-plane
• Components: kube-proxy, kube-scheduler, kube-apiserver, kubelet, kubectl, kubeadm
• CustomResourceDefinition (CRD)

See also

• MicroK8s
• minikube: [status | start | stop | version | addons | addons list | addons enable | dashboard | logs | tunnel | ssh | config | image | delete ], config set minikube start --vm=true, kicbase, ~/.minikube/, minikube --help, Minikube changelog
• Peloton, a unified resource scheduler developed by Uber
• Tigera: Calico, Typha, Canal, calicoctl, calico-kube-controllers, kind: BGPPeer
• Service mesh: Istio, Linkerd, Consul, containerpilot, AWS App Mesh, Kiali, INNOQ, Kuma, Kong Mesh
• Cilium API-aware Networking and Security
• Jaeger tracing
• Container orchestration: Kubernetes, Nomad, Docker Swarm, OpenShift, Mesos, Marathon, AWS Fargate
• Kubernetes cloud services: EKS, GKE (Anthos), AKS, Docker Kubernetes Service (DKS), TKE
• CKA: v1.28: API, Namespace, Pods, secrets, Services, deployments, nodes, Volumes, Ingress, CKS
• Kubernetes: distributions, tools, CKA, CKS, Kubernetes interfaces: CSI, CNI, installation, workloads, networking, kubeadm, Kubernetes API, Kubernetes API Server, kubectl, kubeadm, kubelet, kube-proxy, Cloud services: EKS, GKE, TKE, DKS, Helm, Kubernetes RBAC, Kubernetes deployments, Minikube, Rancher, OpenShift, Charmed Kubernetes, Ingress, Kubernetes scheduler, Kubernetes Finalizers, logging, Kubernetes operator, Orka, kind:, Kubernetes namespaces, Kubernetes dashboard, Kubernetes Metrics Server, Field Selectors, CoreDNS, CRI, Kubernetes Topology Manager, Kubernetes governance: (SIG, KEP), Kustomize, controllers, ReadinessProbe, LivenessProbe, KOPS, K9s, Kui, k3s, ImagePullBackOff, PDB, EndPoints, Kots, metadata, Karpenter, Replicated.com, Kubernetes Authenticating, Kubernetes timeline, Changelog/Versions, service accounts, Kubernetes Pod Lifecycle, Kubernetes Conformance Certified, Kubernetes backup, Kubernetes Pod Security Admission, tEKS, Kubernetes events, Kubernetes ports, Kubernetes policies, Connect, addons, DoKC, Kubernetes control plane, Kubernetes Federation, Kubernetes info, Kubetest2, Sidecar (Kubernetes)

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Source: https://en.wikiversity.org/wiki/DevOps/Kubernetes