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Propagate dependencies

Deployment, Job, Pod, DaemonSet and StatefulSet dependencies (ConfigMaps and Secrets) can be propagated to member clusters automatically. This document demonstrates how to use this feature. For more design details, please refer to dependencies-automatically-propagation

Prerequisites

Karmada has been installed

We can install Karmada by referring to quick-start, or directly run hack/local-up-karmada.sh script which is also used to run our E2E cases.

Enable PropagateDeps feature

PropagateDeps feature gate has evolved to the Beta sine Karmada v1.4 and is enabled by default. If you use the Karmada 1.3 or earlier, you need to enable this feature gate.

kubectl edit deployment karmada-controller-manager -n karmada-system

Add --feature-gates=PropagateDeps=true option.

Example

Create a Deployment mounted with a ConfigMap

apiVersion: apps/v1
kind: Deployment
metadata:
name: my-nginx
labels:
app: my-nginx
spec:
replicas: 2
selector:
matchLabels:
app: my-nginx
template:
metadata:
labels:
app: my-nginx
spec:
containers:
- image: nginx
name: my-nginx
ports:
- containerPort: 80
volumeMounts:
- name: configmap
mountPath: "/configmap"
volumes:
- name: configmap
configMap:
name: my-nginx-config
---
apiVersion: v1
kind: ConfigMap
metadata:
name: my-nginx-config
data:
nginx.properties: |
proxy-connect-timeout: "10s"
proxy-read-timeout: "10s"
client-max-body-size: "2m"

Create a propagation policy with this Deployment and set propagateDeps: true.

apiVersion: policy.karmada.io/v1alpha1
kind: PropagationPolicy
metadata:
name: my-nginx-propagation
spec:
propagateDeps: true
resourceSelectors:
- apiVersion: apps/v1
kind: Deployment
name: my-nginx
placement:
clusterAffinity:
clusterNames:
- member1
- member2
replicaScheduling:
replicaDivisionPreference: Weighted
replicaSchedulingType: Divided
weightPreference:
staticWeightList:
- targetCluster:
clusterNames:
- member1
weight: 1
- targetCluster:
clusterNames:
- member2
weight: 1

Upon successful policy execution, the Deployment and ConfigMap are properly propagated to the member cluster.

$  kubectl --kubeconfig /etc/karmada/karmada-apiserver.config get propagationpolicy
NAME AGE
my-nginx-propagation 16s
$ kubectl --kubeconfig /etc/karmada/karmada-apiserver.config get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
my-nginx 2/2 2 2 22m
# member cluster1
$ kubectl config use-context member1
Switched to context "member1".
$ kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
my-nginx 1/1 1 1 25m
$ kubectl get configmap
NAME DATA AGE
my-nginx-config 1 26m
# member cluster2
$ kubectl config use-context member2
Switched to context "member2".
$ kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
my-nginx 1/1 1 1 27m
$ kubectl get configmap
NAME DATA AGE
my-nginx-config 1 27m