examples/

README

Examples

Resource Interpreter

This example implements a new CustomResourceDefinition(CRD), Workload, and creates a resource interpreter webhook.

Install

For karmada deployed using hack/local-up-karmada.sh, there are karmada-host, karmada-apiserver and three member clusters named member1, member2 and member3.

Step1: Install Workload CRD in karmada-apiserver and member clusters

Install CRD in karmada-apiserver by running the following command:

kubectl --kubeconfig $HOME/.kube/karmada.config --context karmada-apiserver apply -f examples/customresourceinterpreter/apis/workload.example.io_workloads.yaml

Create ClusterPropagationPolicy object to propagate CRD to member clusters:

workload-crd-cpp.yaml:

unfold me to see the yaml

apiVersion: policy.karmada.io/v1alpha1
kind: ClusterPropagationPolicy
metadata:
  name: workload-crd-cpp
spec:
  resourceSelectors:
    - apiVersion: apiextensions.k8s.io/v1
      kind: CustomResourceDefinition
      name: workloads.workload.example.io
  placement:
    clusterAffinity:
      clusterNames:
        - member1
        - member2
        - member3

kubectl --kubeconfig $HOME/.kube/karmada.config --context karmada-apiserver apply -f workload-crd-cpp.yaml

Step2: Deploy webhook configuration in karmada-apiserver

Execute below script:

webhook-configuration.sh

unfold me to see the script

#!/usr/bin/env bash

export ca_string=$(cat ${HOME}/.karmada/ca.crt | base64 | tr "\n" " "|sed s/[[:space:]]//g)
export temp_path=$(mktemp -d)

cp -rf "examples/customresourceinterpreter/webhook-configuration.yaml" "${temp_path}/temp.yaml"
sed -i'' -e "s/{{caBundle}}/${ca_string}/g" "${temp_path}/temp.yaml"
kubectl --kubeconfig $HOME/.kube/karmada.config --context karmada-apiserver apply -f "${temp_path}/temp.yaml"
rm -rf "${temp_path}"

chmod +x webhook-configuration.sh

./webhook-configuration.sh

Step3: Deploy interpreter webhook example in karmada-host

kubectl --kubeconfig $HOME/.kube/karmada.config --context karmada-host apply -f examples/customresourceinterpreter/karmada-interpreter-webhook-example.yaml

Usage

Create a Workload resource and propagate it to the member clusters:

workload-interpret-test.yaml:

unfold me to see the yaml

apiVersion: workload.example.io/v1alpha1
kind: Workload
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  replicas: 3
  paused: false
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx
        name: nginx
---
apiVersion: policy.karmada.io/v1alpha1
kind: PropagationPolicy
metadata:
  name: nginx-workload-propagation
spec:
  resourceSelectors:
    - apiVersion: workload.example.io/v1alpha1
      kind: Workload
      name: nginx
  placement:
    clusterAffinity:
      clusterNames:
        - member1
        - member2
        - member3
    replicaScheduling:
      replicaDivisionPreference: Weighted
      replicaSchedulingType: Divided
      weightPreference:
        staticWeightList:
          - targetCluster:
              clusterNames:
                - member1
            weight: 1
          - targetCluster:
              clusterNames:
                - member2
            weight: 1
          - targetCluster:
              clusterNames:
                - member3
            weight: 1

kubectl --kubeconfig $HOME/.kube/karmada.config --context karmada-apiserver apply -f workload-interpret-test.yaml

InterpretReplica

You can get ResourceBinding to check if the replicas field is interpreted successfully.

kubectl get rb nginx-workload -o yaml 

ReviseReplica

You can check if the replicas field of Workload object is revised to 1 in all member clusters.

kubectl --kubeconfig $HOME/.kube/members.config --context member1 get workload nginx --template={{.spec.replicas}}

Retain

Update spec.paused of Workload object in member1 cluster to true.

kubectl --kubeconfig $HOME/.kube/members.config --context member1 patch workload nginx --type='json' -p='[{"op": "replace", "path": "/spec/paused", "value":true}]'

Check if it is retained successfully.

kubectl --kubeconfig $HOME/.kube/members.config --context member1 get workload nginx --template={{.spec.paused}}

Note: If you want to use Retain function in pull mode cluster, you need to deploy interpreter webhook example in this member cluster.