How does ArgoCD ApplicationSets with Cluster Generator work?

Question

Accepted Answer

**ApplicationSet with Cluster Generator** — automatic deployment to all clusters.

**Example (deploy to all clusters):**
```yaml
apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: myapp-clusters
  namespace: argocd
spec:
  generators:
    - clusters:
        selector:
          matchLabels:
            env: production
        values:
          revision: main
  template:
    metadata:
      name: "myapp-{{name}}"
    spec:
      project: default
      source:
        repoURL: https://github.com/org/k8s-manifests
        targetRevision: "{{values.revision}}"
        path: "overlays/production"
      destination:
        server: "{{server}}"
        namespace: production
      syncPolicy:
        automated:
          prune: true
          selfHeal: true
        syncOptions:
          - CreateNamespace=true
```

**Git Generator (by directories):**
```yaml
generators:
  - git:
      repoURL: https://github.com/org/apps
      revision: main
      directories:
        - path: apps/*
```
Each folder in `apps/` creates an Application with the folder name.

**Matrix Generator (cluster × application):**
```yaml
generators:
  - matrix:
      generators:
        - clusters:
            selector:
              matchLabels:
                env: production
        - list:
            elements:
              - app: frontend
                path: apps/frontend
              - app: backend
                path: apps/backend
```
Creates an Application for each combination: frontend-prod-us, frontend-prod-eu, backend-prod-us, etc.

DevOps: How does ArgoCD ApplicationSets with Cluster Generator work?