Kubernetes —
Orquestração de Containers

# ── kubectl (cliente de linha de comandos) ──────────────────────────
curl -LO "https://dl.k8s.io/release/$(curl -sL https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
sudo install -o root -g root -m 0755 kubectl /usr/local/bin/kubectl
kubectl version --client

# ── minikube ────────────────────────────────────────────────────────
curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64
sudo install minikube-linux-amd64 /usr/local/bin/minikube

# ── iniciar cluster (usa Docker como driver por defeito) ─────────────
minikube start
😄  minikube v1.33.0 on Ubuntu 22.04
✨  Using the docker driver based on existing profile
🏄  Done! kubectl is now configured to use "minikube" cluster

# verificar estado do cluster
kubectl cluster-info
Kubernetes control plane is running at https://127.0.0.1:49153
kubectl get nodes
NAME       STATUS   ROLES           AGE   VERSION
minikube   Ready    control-plane   2m    v1.30.0

brew install kubectl minikube
minikube start --driver=docker

# instalar kubectl e minikube via winget
winget install Kubernetes.kubectl
winget install Kubernetes.minikube

# ou via Chocolatey
choco install kubernetes-cli minikube

# iniciar (requer Hyper-V ou Docker Desktop activo)
minikube start --driver=docker

minikube start           # iniciar o cluster
minikube stop            # parar (preserva o estado)
minikube delete          # eliminar completamente o cluster
minikube status          # ver estado do cluster
minikube dashboard       # abrir dashboard web no browser
minikube tunnel          # expor Services LoadBalancer localmente
minikube addons list     # listar extensões disponíveis
minikube addons enable ingress   # activar Ingress Controller nginx
minikube addons enable metrics-server  # activar métricas (para HPA)

# Ver o estado geral de tudo
kubectl get all -A
NAMESPACE   NAME                          READY   STATUS    RESTARTS   AGE
default     pod/nginx-7f456874d9-xk2m4    1/1     Running   0          5m
default     pod/api-6b9f4c8d7f-p9n3r     1/1     Running   0          3m

# Pod com erro? Descreve para ver o motivo
kubectl describe pod api-6b9f4c8d7f-p9n3r
Events:
  Warning  BackOff   2m   kubelet  Back-off restarting failed container

# Ver os logs do pod problemático
kubectl logs api-6b9f4c8d7f-p9n3r --previous
Error: Cannot connect to database at host 'db': connection refused

# Entrar no container para diagnóstico manual
kubectl exec -it api-6b9f4c8d7f-p9n3r -- sh
/ # env | grep DB_
DB_HOST=db
DB_PORT=5432
/ # ping db
ping: bad address 'db'

# Criar o Pod a partir do manifest
kubectl apply -f pod-nginx.yaml
pod/meu-nginx created

# Ver o estado do Pod (aguarda ficar Running)
kubectl get pod meu-nginx -w
NAME        READY   STATUS              RESTARTS   AGE
meu-nginx   0/1     ContainerCreating   0          3s
meu-nginx   1/1     Running             0          8s

# Redirecionar porta para testar localmente
kubectl port-forward pod/meu-nginx 8080:80
Forwarding from 127.0.0.1:8080 -> 80
# Abre http://localhost:8080 — deves ver a página Nginx

# Ver logs em tempo real
kubectl logs -f meu-nginx

# Eliminar o Pod
kubectl delete pod meu-nginx
pod "meu-nginx" deleted

# Aplicar o Deployment
kubectl apply -f deployment-api.yaml
deployment.apps/api-deployment created

# Ver estado do rollout em tempo real
kubectl rollout status deployment/api-deployment
Waiting for deployment "api-deployment" rollout to finish: 1 of 3 updated...
Waiting for deployment "api-deployment" rollout to finish: 2 of 3 updated...
deployment "api-deployment" successfully rolled out

# Actualizar a imagem (rolling update sem downtime)
kubectl set image deployment/api-deployment api=meuregistry/api:1.6.0
# Ou editar directamente o manifest e aplicar de novo

# Rollback para a versão anterior se algo correr mal
kubectl rollout undo deployment/api-deployment
deployment.apps/api-deployment rolled back

# Ver histórico de revisões
kubectl rollout history deployment/api-deployment
REVISION  CHANGE-CAUSE
1         image: api:1.5.0
2         image: api:1.6.0

# Escalar manualmente o número de réplicas
kubectl scale deployment/api-deployment --replicas=5
deployment.apps/api-deployment scaled

# Dentro de qualquer Pod, podes chamar outro serviço pelo nome:
# http://api-service          (mesmo namespace)
# http://api-service:80       (com porta explícita)
# http://api-service.producao.svc.cluster.local  (FQDN completo)

# Testar DNS de dentro de um Pod de debugging
kubectl run debug --image=curlimages/curl --rm -it -- sh
/ # curl http://api-service/health
{"status":"ok","version":"1.5.0"}
/ # nslookup api-service
Server:    10.96.0.10
Address:   10.96.0.10#53
Name:      api-service.default.svc.cluster.local
Address:   10.100.42.137

# Criar ConfigMap a partir de ficheiro .env
kubectl create configmap api-config --from-env-file=.env

# Criar ConfigMap a partir de valores directos
kubectl create configmap app-config \
  --from-literal=NODE_ENV=production \
  --from-literal=PORT=3000

# Criar Secret (K8s codifica automaticamente em base64)
kubectl create secret generic api-secrets \
  --from-literal=DB_PASSWORD=supersegredo123 \
  --from-literal=JWT_SECRET=chave-secreta

# Verificar (os valores aparecem codificados)
kubectl get secret api-secrets -o yaml
data:
  DB_PASSWORD: c3VwZXJzZWdyZWRvMTIz  # base64

# Descodificar para verificar (em base64)
kubectl get secret api-secrets -o jsonpath='{.data.DB_PASSWORD}' | base64 -d
supersegredo123

# Activar o addon nginx-ingress-controller
minikube addons enable ingress
💡  ingress is an addon maintained by Kubernetes.
🌟  The 'ingress' addon is enabled

# Aplicar o manifest do Ingress
kubectl apply -f ingress.yaml

# Ver IP do Ingress
kubectl get ingress
NAME                CLASS   HOSTS                        ADDRESS        PORTS     AGE
ingress-principal   nginx   app.empresa.pt,api.emp...   192.168.49.2   80, 443   30s

# Testar localmente (adicionar ao /etc/hosts):
# 192.168.49.2  app.empresa.pt api.empresa.pt
curl -H "Host: api.empresa.pt" http://192.168.49.2/health
{"status":"ok"}

# Activar metrics-server (necessário para HPA)
minikube addons enable metrics-server

# Aplicar o HPA
kubectl apply -f hpa.yaml

# Ver estado do HPA
kubectl get hpa
NAME      REFERENCE               TARGETS         MINPODS   MAXPODS   REPLICAS   AGE
api-hpa   Deployment/api-deploy   23%/70%, 0%/80%   2       10        2          1m

# Simular carga (em outro terminal)
kubectl run carga --image=busybox --rm -it -- sh
/ # while true; do wget -q -O- http://api-service/; done

# Observar o HPA escalar em tempo real
kubectl get hpa -w
api-hpa   Deployment/api   85%/70%    2   10   2    2m
api-hpa   Deployment/api   92%/70%    2   10   4    3m  # escalou para 4!
api-hpa   Deployment/api   67%/70%    2   10   4    5m
api-hpa   Deployment/api   12%/70%    2   10   2    8m  # voltou a 2

# ── instalar Helm ───────────────────────────────────────────────────
# Linux / macOS
curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash
# macOS via Homebrew
brew install helm
# Windows via Winget
winget install Helm.Helm

# ── repositórios de Charts ──────────────────────────────────────────
helm repo add stable https://charts.helm.sh/stable
helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx
helm repo update                     # actualizar lista de charts

# ── exemplos de instalação ──────────────────────────────────────────
# Instalar nginx-ingress-controller
helm install ingress-nginx ingress-nginx/ingress-nginx \
  --namespace ingress-nginx --create-namespace

# Instalar PostgreSQL com configuração customizada
helm install meu-postgres bitnami/postgresql \
  --set auth.postgresPassword=segredo \
  --set primary.persistence.size=10Gi \
  --namespace databases --create-namespace

# Instalar Prometheus + Grafana (stack de monitorização)
helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm install kube-prometheus prometheus-community/kube-prometheus-stack \
  --namespace monitoring --create-namespace

helm create minha-api
Creating minha-api

# Estrutura criada:
minha-api/
├── Chart.yaml          # metadados do chart (nome, versão, descrição)
├── values.yaml         # valores por defeito (configuráveis)
├── templates/
│   ├── deployment.yaml # template do Deployment (usa {{ .Values.* }})
│   ├── service.yaml    # template do Service
│   ├── ingress.yaml    # template do Ingress
│   ├── hpa.yaml        # template do HPA
│   └── _helpers.tpl    # funções auxiliares reutilizáveis
└── charts/             # dependências (sub-charts)

# Instalar o chart em modo de desenvolvimento
helm install minha-api ./minha-api \
  --set image.tag=1.5.0 \
  --set replicaCount=3

# Actualizar com novos valores
helm upgrade minha-api ./minha-api \
  --set image.tag=1.6.0