Install components with Helm and Kustomize

$ run as a normal user# run as root (or with sudo)

Skills in this chapter

Install components with Helm and Kustomize; understand CRDs and operators

Install a chart with Helm

A chart is a package of templates; a release is an installed chart with your values.

$helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx
$helm repo update
$helm search repo ingress-nginx
$helm show values ingress-nginx/ingress-nginx > values.yaml
$helm install ingress ingress-nginx/ingress-nginx -n ingress-nginx --create-namespace --set controller.replicaCount=2
$helm list -A
$helm status ingress -n ingress-nginx

5.2

Upgrade and roll back a release

Every change is a new revision; roll back to any old one.

$helm upgrade ingress ingress-nginx/ingress-nginx -n ingress-nginx -f values.yaml
$helm history ingress -n ingress-nginx
$helm rollback ingress 1 -n ingress-nginx
$helm template ingress ingress-nginx/ingress-nginx -f values.yaml > rendered.yaml
$helm uninstall ingress -n ingress-nginx

Command	Does
`helm install NAME CHART`	Install a new release
`helm upgrade --install`	Install or upgrade (good in pipelines)
`-f values.yaml`, `--set k=v`	Your values
`helm get values NAME`	The values in use
`helm template`	Render YAML without installing
`helm rollback NAME REV`	Go back to a revision

5.3

Change YAML with Kustomize

A kustomization.yaml lists resources and changes (name prefix, labels, image tags, patches). kubectl apply -k builds and applies it.

base/kustomization.yaml

resources:
  - deployment.yaml
  - service.yaml

overlays/prod/kustomization.yaml

resources:
  - ../../base
namespace: shop-prod
namePrefix: prod-
labels:
  - pairs: { env: prod }
images:
  - name: ghcr.io/s0sta/shop
    newTag: "1.4.0"
patches:
  - target: { kind: Deployment, name: web }
    patch: |-
      - op: replace
        path: /spec/replicas
        value: 4

$kubectl kustomize overlays/prod
$kubectl apply -k overlays/prod
$kubectl diff -k overlays/prod

5.4

Understand CRDs and operators

A CustomResourceDefinition adds a new object type to the API (for example Certificate from cert-manager). An operator is a controller that watches those objects and does the work.

$kubectl get crd
$kubectl api-resources | grep cert-manager
$kubectl explain certificate.spec
$kubectl get certificates -A

Remember

Install the CRDs before objects of that type — otherwise kubectl apply says "no matches for kind".

All commands in this chapter