11_crds.adoc

CRDs & Controllers

Custom Resources extend the API

Custom Controllers provide the functionality - continually maintains the desired state - to monitor its state and reconcile the resource to match with the configuration

https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/custom-resources/

https://kubernetes.io/docs/tasks/access-kubernetes-api/custom-resources/custom-resource-definitions/

Custom Resource Definitions (CRDs) in version 1.7

CRDs

$ kubectl get crds
$ kubectl api-resources

Example CRD

apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
  name: pizzas.mykubernetes.burrsutter.com
  labels:
    app: pizzamaker
    mylabel: stuff
  annotations:
    "yourannotation": morestuff
spec:
  group: mykubernetes.burrsutter.com
  scope: Namespaced
  version: v1beta2
  names:
    kind: Pizza
    listKind: PizzaList
    plural: pizzas
    singular: pizza
    shortNames:
    - pz

Add Pizzas

$ kubectl apply -f pizza-crd.yaml

Now part of the API

$ kubectl get crds | grep pizza
pizzas.mykubernetes.burrsutter.com                          2019-09-04T19:40:09Z
$ kubectl api-resources | grep burr

Make some Pizzas

$ kubectl create namespace pizzahat

$ kubectl config set-context --current --namespace=pizzahat

$ kubectl apply -f cheese-pizza.yaml

$ kubectl get pizzas

$ kubectl describe pizza burrcheese

Make more Pizzas

$ kubectl apply -f meat-lovers.yaml

$ kubectl apply -f veggie-lovers.yaml

$ kubectl get pizzas --all-namespaces

Eat all Pizzas

$ kubectl delete pizzas --all

Example CRD

Controllers

Build a controller via Metacontroller: https://metacontroller.app/guide/create/

https://github.com/GoogleCloudPlatform/metacontroller

Note: Future?

Setup Metacontroller

$ kubectl create namespace metacontroller

$ kubectl apply -f https://raw.githubusercontent.com/GoogleCloudPlatform/metacontroller/master/manifests/metacontroller-rbac.yaml

$ kubectl apply -f https://raw.githubusercontent.com/GoogleCloudPlatform/metacontroller/master/manifests/metacontroller.yaml

$ kubectl get pods --all-namespaces

$ stern metacontroller-0 -n metacontroller

$ kubectl apply -f pizza-controller.yaml

metacontroller-0 metacontroller I0904 22:23:35.324855       1 metacontroller.go:148] sync CompositeController pizza-controller
metacontroller-0 metacontroller I0904 22:23:35.324899       1 factory.go:104] Starting shared informer for pizzas in mykubernetes.burrsutter.com/v1beta2
metacontroller-0 metacontroller I0904 22:23:35.324940       1 factory.go:104] Starting shared informer for pods in v1
metacontroller-0 metacontroller I0904 22:23:35.325019       1 controller.go:165] Starting Pizza CompositeController
metacontroller-0 metacontroller I0904 22:23:35.325029       1 controller.go:169] Waiting for Pizza CompositeController caches to sync
metacontroller-0 metacontroller I0904 22:23:35.325039       1 controller.go:32] Waiting for caches to sync for Pizza controller
metacontroller-0 metacontroller I0904 22:23:35.325453       1 reflector.go:202] Starting reflector *unstructured.Unstructured (30m0s) from metacontroller.app/dynamic/informer/factory.go:111
metacontroller-0 metacontroller I0904 22:23:35.325476       1 reflector.go:240] Listing and watching *unstructured.Unstructured from metacontroller.app/dynamic/informer/factory.go:111
metacontroller-0 metacontroller I0904 22:23:35.325947       1 reflector.go:202] Starting reflector *unstructured.Unstructured (30m0s) from metacontroller.app/dynamic/informer/factory.go:111
metacontroller-0 metacontroller I0904 22:23:35.325963       1 reflector.go:240] Listing and watching *unstructured.Unstructured from metacontroller.app/dynamic/informer/factory.go:111
metacontroller-0 metacontroller I0904 22:23:35.525234       1 shared_informer.go:123] caches populated
metacontroller-0 metacontroller I0904 22:23:35.525259       1 controller.go:39] Caches are synced for Pizza controller

Add Pizza Controller

kubectl -n pizzahat create configmap pizza-controller --from-file=sync.py

kubectl -n pizzahat apply -f webhook-py.yaml

Deploy some Pizzas

$ stern metacontroller-0 -n metacontroller

$ stern pizza-controller

$ watch kubectl get pods

$ kubectl -n pizzahat apply -f veggie-lovers.yaml

$ kubectl logs burrveggie

Eat the Pizza

$ kubectl delete pizza burrveggie
$ kubectl delete namespace pizzahat

Kafka via OperatorHub

$ kubectl create namespace franz

$ kubectl config set-context --current --namespace=franz

$ curl -sL https://github.com/operator-framework/operator-lifecycle-manager/releases/download/0.12.0/install.sh | bash -s 0.12.0

$ kubectl create -f https://operatorhub.io/install/strimzi-kafka-operator.yaml

$ kubectl get csv -n operators

$ kubectl get crds | grep kafka

$ watch kubectl get pods

$ kubectl apply -f https://raw.githubusercontent.com/burrsutter/9stepsawesome/master/kubefiles/kafka-strimzi-minikube.yml

$ kubectl get kafkas

Clean up

$ kubectl delete kafka burr-cluster
$ kubectl delete namespace franz