Kubernetes Management Techniques

Run, Create and Expose Generators

• These commands use helper templates called "generators"

• Every resource in Kubernetes has a specification or "spec"

• kubectl create deployment sample --image nginx --dry-run -o yaml

• You can output those templates with --dry-run -o yaml

• You can use those YAML default as a starting point for your own templates

• Generators are "opinionated defaults"

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: sample
  name: sample
spec:
  replicas: 1
  selector:
    matchLabels:
      app: sample
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: sample
    spec:
      containers:
      - image: nginx
        name: nginx
        resources: {}
status: {}

Three Management Approaches

• Imperative commands: run, expose, scale, edit, create deployment

  • best for dev / learning / personal projects

  • easy to learn, hardest to manage over time

• Imperative objects: create -f file.yml, replace -f file.yml, delete -f file.yml

  • good for prod of small environments, single file per command

  • store your changes in git-based yaml files

  • hard to automate

• Declarative objects: apply -f file.yaml or dir\, diff

  • best for prod, easier to automate

  • harder to understand and predict changes

• Most important rule:

  • don't mix these three approaches