Kubernetes Overview
Kubenerets is an open source container orchestration system for deployment scaling and management. K8s is ideal for microservice architecture
This page contains one line overview of concepts to quick recap kubernetes :)
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Cluster
A logical grouping of all components within a cluster
Namespace:
A named logical grouping of Kubernetes component within cluster
Node:
VIrtual Machine or underlying server. There are 2 types of node in a cluster.
Control Plane (Manages Worker Nodes):
Consists of API Server
Scheduler
Control Manager
etcd
Kubelet
CoreDNS
Worker Nodes (Workload run here)
Kubelet
Kubeproxy
Container Runtime
Pods & Containers
Pod:
Smallest unit in k8s. It is abstraction over containers.
Service:
Used to allocate static IP addresses and DNS names for set of pods
Ingress:
Translates HTTP/s rules to point to service.
API Server:
Helps users interact with k8s cluster using kubectl or by sending HTTP requests.
Kubelet:
Helps interact with nodes via API server. Present on all nodes
Kubectl:
Command line terminal for k8s
Cloud Controller Manager:
Allows you to link a cloud service provider
Controller Manager:
Watches and changes current state back to the desired state.
Scheduler:
Determines where to place pods on nodes
Kubeproxy:
Provides routing & filtering rules for traffic to pods
Network Policy:
Acts as a virtual firewall bewtween namespaces, pods, nodes, etc
ConfigMap:
Used to store Non Confidential data into key value pair.
Secret:
Stores sensitive data like passwords, tokens or key.
Volumes:
Mounting storage to store the data for application to use and preserve.
Replica Set:
Maintain a stable set of replica pods running at given time.
Deployment:
It is a blueprint for a pod.
In-Tree:
Plugins and components or functionality that are provided by default or resides in main repository
Out-Tree:
Plugins and component or functionality that must be installed manually that replaces default behaviour.
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