Kubernetes: basic resources and concepts

Using K8s feels like being air traffic controller, sometimes.

Master Server Components

  • etcd — config store accessible to all cluster nodes
  • kube-apiserver — config workloads and org unit; REST + kubectl client
  • kube-controller-manager manages controllers, state saved to etcd
  • kube-scheduler — assigns workloads to specific nodes
  • cloud-controller-manager — bridge to specific cloud provider

Node Server Components

  • Node is a server that preforms work.
  • Container Runtime is typically Docker, but can be rkt or runc too.
  • kubelet is a main contact point for each node with the cluster group. Work is received as manifest.
  • kube-proxy lets manage sub-netting and makes services available to other components. Can do primitive load-balancing.

Kubernetes Objects and Workloads

Pods

Replication Controllers and Replication Sets

Deployments

apiVersion: apps/v1
kind: Deployment
metadata:
name: apache-deployment
labels:
app: web
spec:
replicas: 5
selector:
matchLabels:
app: web
template:
metadata:
labels:
app: web
spec:
containers:
- name: apache-container
image: httpd:2.4.35

Stateful Sets

Daemon Sets

Jobs and Cron Jobs

Other Kubernetes Components

Services

Volumes and Persistent Volumes

Namespaces

Labels and Annotations

Secrets

ConfigMap

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Father. Husband. Solutions developer profesionally (software quite often). Arsenal supporter. Cyclist.

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Adam Brodziak

Adam Brodziak

Father. Husband. Solutions developer profesionally (software quite often). Arsenal supporter. Cyclist.

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