# Karmada — Multi-Cloud & Multi-Cluster Kubernetes Orchestration

> CNCF-incubated control plane that turns a fleet of Kubernetes clusters into a single addressable API surface.

## Install

Save as a script file and run:

# Karmada — Multi-Cloud & Multi-Cluster Kubernetes Orchestration

## Quick Use
```bash
# Install kubectl-karmada plugin
kubectl krew install karmada

# Bootstrap Karmada on an existing cluster
kubectl karmada init

# Join a member cluster
kubectl karmada join member1 --cluster-kubeconfig=member1.kubeconfig

# Apply a PropagationPolicy
kubectl apply -f deployment.yaml --kubeconfig ~/.kube/karmada-apiserver.config
```

## Introduction
Karmada (Kubernetes Armada) was open sourced by Huawei and is now a CNCF project. It lets you run one "host" Kubernetes control plane that schedules workloads onto many "member" clusters — across clouds, regions, or on-prem sites — while each workload stays a normal Deployment, Service, or CRD.

## What Karmada Does
- Provides a super-API server that aggregates Pods, Services, and CRDs across clusters.
- Schedules workloads with placement policies (label, region, taint, weight, resource fit).
- Fails over or rebalances Deployments when a cluster goes unhealthy.
- Mirrors ConfigMaps, Secrets, and CRDs to target clusters with override rules.
- Supports pull mode (edge) and push mode (central) for member-cluster control.

## Architecture Overview
The Karmada control plane is a Kubernetes itself — etcd, kube-apiserver, scheduler, controller-manager, plus Karmada-specific components (karmada-webhook, karmada-aggregated-apiserver, karmada-scheduler, karmada-controller-manager). Member clusters run a tiny agent (in pull mode) or are reached via kubeconfig (push mode). Propagation policies resolve which clusters get which objects.

## Self-Hosting & Configuration
- `kubectl karmada init` produces a ready control plane on any kubeadm cluster.
- Helm charts and the Karmada Operator cover production deployments.
- Store cluster kubeconfigs as Secrets; rotate automatically with cert-manager.
- Use PropagationPolicy and ClusterPropagationPolicy for namespace vs. cluster scope.
- OverridePolicy rewrites image tags, resources, or args per target cluster.

## Key Features
- Native kubectl experience across dozens of clusters.
- Declarative cross-cluster service discovery via MCS (Multi-Cluster Services).
- Differential config per cluster through strategic-merge or JSON-patch overrides.
- Works with any CNCF-conformant Kubernetes — EKS, GKE, AKS, OpenShift, k3s.
- Pluggable scheduling: priority, capacity-aware, CPU/GPU topology-aware.

## Comparison with Similar Tools
- **Kubefed v2** — archived predecessor; Karmada is considered its spiritual successor.
- **Cluster API** — cluster lifecycle; Karmada is workload lifecycle across clusters.
- **Rancher Fleet** — GitOps-first multi-cluster; Karmada is API-first.
- **Google Anthos / Azure Arc** — managed multi-cluster, vendor-locked.
- **OpenShift ACM** — Red Hat multi-cluster with a GUI; Karmada is upstream and free.

## FAQ
**Q:** Do pods move between clusters automatically?
A: Deployments can reschedule on cluster failure; individual pods do not migrate because Kubernetes pods are not live-migratable.

**Q:** How is cross-cluster networking solved?
A: Karmada handles orchestration; pair it with Submariner, Cilium Cluster Mesh, or Istio multicluster for the data plane.

**Q:** Can I mix K8s versions?
A: Yes, within two minor versions of the control plane per project guidance.

**Q:** CNCF status?
A: Incubating as of 2023 — used in production by Huawei Cloud, ICBC, and others.

## Sources
- https://github.com/karmada-io/karmada
- https://karmada.io/docs/

---
Source: https://tokrepo.com/en/workflows/5639db47-3919-11f1-9bc6-00163e2b0d79
Author: Script Depot