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03_KIND_EXTRA_PORTS_MAPPING.md

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Uso de Extra Port Mappings no Kind

Durante a leitura da documentação do kind encontrei o trecho abaixo que trata das extra port mappings:

If you are running Docker without the Docker Desktop Application on Linux,
you can simply send traffic to the node IPs from the host without extra port mappings.

https://kind.sigs.k8s.io/docs/user/configuration/#extra-port-mappings

Sempre utilizei extra port mappings para acessar Services do tipo NodePort criados no cluster, mas após a leitura da documentação decidi tentar remover as extra port mappings.

Um ponto positivo ao uso de extra port mappings é a possibilidade de acessar o Service sem conhecer o(s) endereço(s) IP dos Nodes, basta acessar localhost:hostPort.

Diferença na Criação do Cluster

1 - Cluster com Extra Port Mappings

apiVersion: kind.x-k8s.io/v1alpha4
kind: Cluster 
nodes:
  - role: control-plane
    extraPortMappings:
      - containerPort: 32500            # nodePort exposta pelo Service do tipo NodePort
        hostPort: 2500                  # porta para acessar o Service em localhost
        listenAddress: "127.0.0.1"
        protocol: tcp
  - role: worker
  - role: worker

2 - Cluster sem Extra Port Mappings

apiVersion: kind.x-k8s.io/v1alpha4
kind: Cluster
nodes:
    - role: control-plane
    - role: worker
    - role: worker

Validando Acesso com e sem Extra Port Mappings

1 - Criando o cluster

kind create cluster --config - <<EOF
  apiVersion: kind.x-k8s.io/v1alpha4
  kind: Cluster
  nodes:
      - role: control-plane
        extraPortMappings:
          - containerPort: 32500
            hostPort: 2500
            listenAddress: "127.0.0.1"
            protocol: tcp      
      - role: worker
      - role: worker
EOF

2 - Manifesto para criação dos Services e Pod

# https://kubernetes.io/docs/reference/kubernetes-api/service-resources/service-v1/#ServiceSpec
# https://kubernetes.io/docs/concepts/services-networking/service/#publishing-services-service-types
# SERVICE_SEM_EXTRA_PORT_MAPPINGS
apiVersion: v1
kind: Service
metadata:
  name: nodeport-service-1
spec:
  type: NodePort
  selector:
    app: http-echo-pod  
  ports:
    - name: no-extra-port-mappings
      nodePort: 30500
      port: 3000
      targetPort: 3500
      protocol: TCP

--- 

# SERVICE_USANDO_EXTRA_PORT_MAPPINGS
apiVersion: v1
kind: Service
metadata:
  name: nodeport-service-2
spec:
  type: NodePort
  selector:
    app: http-echo-pod  
  ports:
    - name: with-extra-port-mappings
      nodePort: 32500
      port: 2900
      targetPort: 3500
      protocol: TCP      

---

# https://kubernetes.io/docs/reference/kubernetes-api/workload-resources/pod-v1/#ports
# https://github.com/hashicorp/http-echo
apiVersion: v1
kind: Pod
metadata:
  name: http-echo
  labels:
    app: http-echo-pod
spec:
  containers:
    - name: http-echo-container
      image: hashicorp/http-echo
      args:
        - --listen=:3500
        - -text=hello-world
      ports:
        - name: http-echo-port
          containerPort: 3500
          protocol: TCP
  restartPolicy: Always

3 - Validando as chamadas para os Services usando o endereço IP dos Nodes e localhost

# obtendo endereço IP dos Nodes
$kubectl get nodes -o wide 
  NAME                 ROLES           VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE
  kind-control-plane   control-plane   v1.25.3   172.18.0.4    <none>        Ubuntu 22.04.1 LTS
  kind-worker          <none>          v1.25.3   172.18.0.2    <none>        Ubuntu 22.04.1 LTS
  kind-worker2         <none>          v1.25.3   172.18.0.3    <none>        Ubuntu 22.04.1 LTS

# aplicando manifestos
$kubectl apply -f manifest.yaml                          
  service/nodeport-service-1 created
  service/nodeport-service-2 created
  pod/http-echo created

# obtendo informações dos recursos(Service e Pod) criados
$kubectl get all -o wide --show-labels
  NAME            READY   STATUS    IP           NODE          LABELS
  pod/http-echo   1/1     Running   10.244.2.2   kind-worker   app=http-echo-pod

  NAME                        TYPE       CLUSTER-IP    EXTERNAL-IP  PORT(S)         SELECTOR
  service/nodeport-service-1  NodePort   10.96.97.165  <none>       3000:30500/TCP  app=http-echo-pod
  service/nodeport-service-2  NodePort   10.96.7.65    <none>       2900:32500/TCP  app=http-echo-pod

# TESTANDO_SERVICE_SEM_EXTRA_PORT_MAPPINGS
$curl 172.18.0.2:30500 && curl 172.18.0.3:30500 && curl 172.18.0.4:30500
  hello-world
  hello-world
  hello-world

# TESTANDO_SERVICE_COM_EXTRA_PORT_MAPPINGS
$curl 172.18.0.2:32500 && curl 172.18.0.3:32500 && curl 172.18.0.4:32500
  hello-world
  hello-world
  hello-world

$curl localhost:2500  # porta mapeada no manifesto do cluster
  hello-world