ArgoCD (Hub cluster) manages:
├── dev-cluster     (namespace: apps-dev)
├── staging-cluster (namespace: apps-staging)
└── prod-cluster    (namespace: apps-prod)

argocd cluster add prod-context --name production
argocd cluster list

main branch → deploy to dev (auto)
    ↓ tag/PR merge
staging branch → deploy to staging (auto)
    ↓ manual approval
prod branch → deploy to prod (manual sync required)

# Backup ArgoCD state
argocd-applicationset-controller backup
kubectl get applications -n argocd -o yaml > apps-backup.yaml
kubectl get appprojects -n argocd -o yaml > projects-backup.yaml

# ArgoCD restores from Git automatically - it's self-healing
# But backup Application CRDs for DR

apiVersion: argoproj.io/v1alpha1
kind: ArgoCD
metadata:
  name: argocd
spec:
  ha:
    enabled: true     # Redis HA, multiple app controller replicas
  server:
    replicas: 2
  applicationSet:
    replicas: 2

# argocd-rbac-cm ConfigMap
policy.csv: |
  # Admins can do everything
  p, role:admin, *, *, *, allow
  
  # Devs can sync and view only
  p, role:developer, applications, get, */*, allow
  p, role:developer, applications, sync, dev-*/*, allow
  
  # Map GitHub teams to roles
  g, myorg:platform-team, role:admin
  g, myorg:developers, role:developer

# ArgoCD Notifications
apiVersion: v1
kind: ConfigMap
metadata:
  name: argocd-notifications-cm
data:
  trigger.on-sync-failed: |
    - when: app.status.operationState.phase in ['Error', 'Failed']
      send: [slack-message]
  template.slack-message: |
    message: |
      Application {{.app.metadata.name}} sync {{.app.status.operationState.phase}}
      Repo: {{.app.spec.source.repoURL}}
      Commit: {{.app.status.operationState.operation.sync.revision}}
  service.slack: |
    token: $slack-token
    username: ArgoCD

# ArgoCD server webhook endpoint
https://argocd.company.com/api/webhook

# Application management
argocd app list
argocd app get myapp
argocd app sync myapp
argocd app sync myapp --dry-run    # Preview sync without applying
argocd app diff myapp              # Show diff between Git and cluster
argocd app history myapp           # Show sync history
argocd app rollback myapp 3        # Rollback to revision 3

# Clusters
argocd cluster add context-name
argocd cluster list

# Projects
argocd proj list
argocd proj get team-backend
argocd proj role list team-backend

# Login
argocd login argocd.company.com --sso
argocd logout

# App-of-apps bootstrap
argocd app create root-app \
  --repo https://github.com/org/gitops \
  --path argocd-apps \
  --dest-server https://kubernetes.default.svc \
  --dest-namespace argocd \
  --sync-policy automated \
  --auto-prune \
  --self-heal