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API Versioning

API Version

  • apiVersion: api-group/api-version
  • alpha, beta and stable
  • check:
  • kubectl api-versions

  • kubectl api-resources

  • k8s supports multiple version. handle multiple version:

  • preferred
    • typically the latest stable version of that resource.
    • eg: apps/v1 for deploymnet.
  • stored
    • version in which Kubernetes stores resource data in its etcd database, internally.
  • enable version. eg:
  • kube-apiserver.yaml --> add --runtime-config=rbac.authorization.k8s.io/v1alpha1

API Deprecations rules

rule-1

  • API element may only be removed, by incrementing the version.
  • img.png
  • in yaml it can be still alpha1, but internally it switch to alpha2.
  • since alpha2 is preferred and stored version.

rule-2

  • API version must be able to round-trip in given release without information loss.
  • img_3.png

rule-3

  • older version must be supported for some duration
  • GA/stable - 12 months or 3 releases
  • beta - 12 months or 3 releases
  • alpha - anytime deprecate.

rule-4

  • v2 just now came and released in current release.
  • then it can be become preferred/stored.

rule-5

  • v1-Alpha1 > v1-Alpha2 > V1-beta1 > v1-beta2 > v1
  • v2-Alpha1 > v2-Alpha2 > V1-beta1 > v1-beta2 > v2 > after this can deprecate v1.
  • eg:
  • img_2.png
  • img_1.png

Kubectl Convert

  • install this utility first. check official doc.
  • https://kubernetes.io/docs/tasks/tools/install-kubectl-linux/#install-kubectl-convert-plugin 
    - steps (linux)
  - curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl-convert"
  - curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl-convert.sha256"
  - echo "$(cat kubectl-convert.sha256) kubectl-convert" | sha256sum --check
  - sudo install -o root -g root -m 0755 kubectl-convert /usr/local/bin/kubectl-convert
  - kubectl convert --help
  • kubectl convert -f old-file.yaml --output-version apps/v2 --> it will priny new converted yaml file.
  • eg: k convert -f ingress-old.yaml --output-version networking.k8s.io/v1 > ingress-new.yaml img_4.png