App-of-Apps e Multi-Cluster

App-of-Apps Pattern

O padrão App-of-Apps gerencia múltiplas aplicações ArgoCD a partir de uma única Application raiz.

# root-app.yaml
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: root
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/org/infra.git
    path: argocd/apps
    directory:
      recurse: true
  destination:
    server: https://kubernetes.default.svc
    namespace: argocd
  syncPolicy:
    automated:
      prune: true
      selfHeal: true

# argocd/apps/ingress.yaml
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: ingress-nginx
  namespace: argocd
  finalizers:
    - resources-finalizer.argocd.argoproj.io
spec:
  project: default
  source:
    repoURL: https://github.com/org/infra.git
    path: charts/ingress-nginx
    helm:
      values: |
        controller:
          replicaCount: 3
  destination:
    server: https://kubernetes.default.svc
    namespace: ingress
  syncPolicy:
    automated: {}

# argocd/apps/monitoring.yaml
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: kube-prometheus
  namespace: argocd
spec:
  project: monitoring
  source:
    repoURL: https://prometheus-community.github.io/helm-charts
    chart: kube-prometheus-stack
    targetRevision: 56.0.0
    helm:
      values: |
        grafana:
          adminPassword: admin
  destination:
    server: https://kubernetes.default.svc
    namespace: monitoring

Vantagens

- Declarativo: adicionar/remover apps = git commit
- Orquestração: hooks, sync waves, dependências
- Visibilidade: dashboard mostra todas as apps
- RBAC: projects isolam por app

Sync Waves — Ordem de Deploy

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: database
  annotations:
    argocd.argoproj.io/sync-wave: "0"
---
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: backend
  annotations:
    argocd.argoproj.io/sync-wave: "1"
---
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: frontend
  annotations:
    argocd.argoproj.io/sync-wave: "2"

Multi-Cluster

# Adicionar cluster externo
argocd cluster add context-name \
  --name prod-us-east \
  --label environment=prod \
  --label region=us-east-1

argocd cluster list

# Kubeconfig de outro cluster
argocd cluster add minikube --name dev-local

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: app-prod
spec:
  project: default
  source:
    repoURL: https://github.com/org/app.git
    path: overlays/prod
  destination:
    name: prod-us-east       # nome do cluster registrado
    namespace: app
    server: https://192.168.1.100:6443  # ou URL direta
---
# Destination com cluster selector
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: app-all-prod
spec:
  destination:
    name: in-cluster
  ignoreDifferences:
    - group: apps
      kind: Deployment
      jsonPointers:
        - /spec/replicas
---

Cluster Secrets

apiVersion: v1
kind: Secret
metadata:
  name: prod-cluster
  namespace: argocd
  labels:
    argocd.argoproj.io/secret-type: cluster
type: Opaque
stringData:
  name: prod-us-east
  server: https://192.168.1.100:6443
  config: |
    {
      "bearerToken": "...",
      "tlsClientConfig": {
        "insecure": false,
        "caData": "..."
      }
    }

ApplicationSets — Templates Paramétricos

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: multi-env
spec:
  generators:
    - list:
        elements:
          - cluster: dev
            url: https://192.168.1.10:6443
          - cluster: staging
            url: https://192.168.1.20:6443
          - cluster: prod
            url: https://192.168.1.30:6443
  template:
    metadata:
      name: '{{cluster}}-app'
    spec:
      project: default
      source:
        repoURL: https://github.com/org/app.git
        targetRevision: HEAD
        path: 'overlays/{{cluster}}'
      destination:
        server: '{{url}}'
        namespace: 'app-{{cluster}}'
      syncPolicy:
        automated: {}

argocd appset list
argocd appset get multi-env

App-of-Apps = app raiz que gerencia apps filhas. Sync Waves controlam ordem (banco → backend → frontend). ApplicationSets geram apps parametrizadas para múltiplos clusters/ambientes.