Procedimiento validado para desplegar un clúster de Kubernetes v1.16.0 sobre CentOS 7 empleando repositorios accesibles desde China.

1. Requisitos

• CentOS 7 con kernel 3.10 o superior.
• Mínimo 2 vCPU y 2 GB de RAM por máquina.
• IP fija para el API server; en este ejemplo se usa 192.168.99.104.

2. Instalación de Docker CE

En todos los nodos ejecutar:

DOCKER_VERSION="18.09.9-3.el7"

yum install -y yum-utils device-mapper-persistent-data lvm2
yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
yum install -y docker-ce-${DOCKER_VERSION}
systemctl enable docker --now

3. Acondicionamiento del sistema

El siguiente bloque desactiva el firewall, SELinux y swap, y configura los parámetros de red necesarios para Kubernetes.

#!/bin/bash
set -e

# Firewall
systemctl stop firewalld
systemctl disable firewalld

# SELinux
setenforce 0 2>/dev/null || true
sed -i 's/SELINUX=.*/SELINUX=disabled/' /etc/selinux/config
sed -i 's/SELINUX=.*/SELINUX=disabled/' /etc/sysconfig/selinux 2>/dev/null || true

# Swap
swapoff -a
sed -i '/[[:space:]]\/swap[[:space:]]/d' /etc/fstab

# Parámetros de red para pods
modprobe br_netfilter
cat > /etc/sysctl.d/k8s.conf <<'EOF'
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
EOF
sysctl --system

4. Instalación de kubeadm, kubelet y kubectl

Crear el repositorio de Aliyun para Kubernetes e instalar los binarios de la versión 1.16.0 en todos los nodos:

K8S_VERSION="1.16.0"

cat > /etc/yum.repos.d/kubernetes.repo <<EOF
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
       https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

yum install -y \
  kubelet-${K8S_VERSION}-0 \
  kubeadm-${K8S_VERSION}-0 \
  kubectl-${K8S_VERSION}-0

systemctl enable kubelet --now

5. Inicialización del nodo maestro

Reemplace 192.168.99.104 por la IP de su nodo maestro:

API_IP="192.168.99.104"
POD_NETWORK="10.244.0.0/16"

kubeadm init \
  --image-repository registry.aliyuncs.com/google_containers \
  --kubernetes-version v1.16.0 \
  --apiserver-advertise-address ${API_IP} \
  --pod-network-cidr ${POD_NETWORK} \
  --token-ttl 0

Configurar el acceso local de kubectl:

mkdir -p ${HOME}/.kube
cp -i /etc/kubernetes/admin.conf ${HOME}/.kube/config
chown $(id -u):$(id -g) ${HOME}/.kube/config

Para recuperar el comando de unión de los nodos trabajadores:

kubeadm token create --print-join-command

6. Incorporación de nodos trabajadores

En cada nodo trabajador, tras completar los pasos 2, 3 y 4, ejecute el comando de kubeadm join generado en el paso anterior. Ejemplo:

kubeadm join 192.168.99.104:6443 \
  --token <token> \
  --discovery-token-ca-cert-hash sha256:<hash>

Desde el maestro verifique el registro:

kubectl get nodes

7. Despliegue de Flannel

Parra que los nodos cambien a estado Ready, aplique un complemento de red. Guarde el siguienet manifiesto como flannel-china.yml:

---
apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
  name: flannel.restricted
  annotations:
    seccomp.security.alpha.kubernetes.io/allowedProfileNames: docker/default
    seccomp.security.alpha.kubernetes.io/defaultProfileName: docker/default
spec:
  privileged: false
  volumes:
    - configMap
    - secret
    - emptyDir
    - hostPath
  allowedHostPaths:
    - pathPrefix: "/etc/cni/net.d"
    - pathPrefix: "/etc/kube-flannel"
    - pathPrefix: "/run/flannel"
  readOnlyRootFilesystem: false
  runAsUser:
    rule: RunAsAny
  supplementalGroups:
    rule: RunAsAny
  fsGroup:
    rule: RunAsAny
  allowPrivilegeEscalation: false
  defaultAllowPrivilegeEscalation: false
  allowedCapabilities: ['NET_ADMIN']
  defaultAddCapabilities: []
  requiredDropCapabilities: []
  hostPID: false
  hostIPC: false
  hostNetwork: true
  hostPorts:
    - min: 0
      max: 65535
  seLinux:
    rule: 'RunAsAny'
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
  name: flannel
rules:
  - apiGroups: ['extensions']
    resources: ['podsecuritypolicies']
    verbs: ['use']
    resourceNames: ['flannel.restricted']
  - apiGroups: [""]
    resources: ["pods"]
    verbs: ["get"]
  - apiGroups: [""]
    resources: ["nodes"]
    verbs: ["list", "watch"]
  - apiGroups: [""]
    resources: ["nodes/status"]
    verbs: ["patch"]
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: flannel
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: flannel
subjects:
  - kind: ServiceAccount
    name: flannel
    namespace: kube-system
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: flannel
  namespace: kube-system
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: flannel-cfg
  namespace: kube-system
  labels:
    app: flannel
data:
  cni-conf.json: |
    {
      "name": "cbr0",
      "cniVersion": "0.3.1",
      "plugins": [
        {
          "type": "flannel",
          "delegate": {
            "hairpinMode": true,
            "isDefaultGateway": true
          }
        },
        {
          "type": "portmap",
          "capabilities": {
            "portMappings": true
          }
        }
      ]
    }
  net-conf.json: |
    {
      "Network": "10.244.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: kube-flannel-ds
  namespace: kube-system
  labels:
    app: flannel
spec:
  selector:
    matchLabels:
      app: flannel
  template:
    metadata:
      labels:
        app: flannel
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
              - matchExpressions:
                  - key: beta.kubernetes.io/os
                    operator: In
                    values:
                      - linux
                  - key: beta.kubernetes.io/arch
                    operator: In
                    values:
                      - amd64
      hostNetwork: true
      tolerations:
        - operator: Exists
          effect: NoSchedule
      serviceAccountName: flannel
      initContainers:
        - name: install-cni
          image: quay-mirror.qiniu.com/coreos/flannel:v0.11.0-amd64
          command:
            - cp
          args:
            - -f
            - /etc/kube-flannel/cni-conf.json
            - /etc/cni/net.d/10-flannel.conflist
          volumeMounts:
            - name: cni
              mountPath: /etc/cni/net.d
            - name: flannel-cfg
              mountPath: /etc/kube-flannel/
      containers:
        - name: flannel
          image: quay-mirror.qiniu.com/coreos/flannel:v0.11.0-amd64
          command:
            - /opt/bin/flanneld
          args:
            - --ip-masq
            - --kube-subnet-mgr
          resources:
            requests:
              cpu: "100m"
              memory: "50Mi"
            limits:
              cpu: "100m"
              memory: "50Mi"
          securityContext:
            privileged: false
            capabilities:
              add: ["NET_ADMIN"]
          env:
            - name: POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name
            - name: POD_NAMESPACE
              valueFrom:
                fieldRef:
                  fieldPath: metadata.namespace
          volumeMounts:
            - name: run
              mountPath: /run/flannel
            - name: flannel-cfg
              mountPath: /etc/kube-flannel/
      volumes:
        - name: run
          hostPath:
            path: /run/flannel
        - name: cni
          hostPath:
            path: /etc/cni/net.d
        - name: flannel-cfg
          configMap:
            name: flannel-cfg

Aplicar el manifiesto y verificar el estado de los nodos:

kubectl apply -f flannel-china.yml
kubectl get nodes -o wide