《Kubernetes 集群安装》

Kubernetes（K8s）是容器编排的事实标准。本文给出主流安装方式：apt 一键安装 kubeadm/kubelet/kubectl。

1 方法一：apt 一键安装（Ubuntu）

以下脚本（曾用于 Ubuntu 16.04，容器内亦可安装）添加国内镜像源并安装 k8s 组件：

        
      
#!/bin/bash

set -e
mydir="$(dirname $(readlink -f $0))"
cd $mydir

KUBE_VERSION="1.16.4"

apt_add_k8s_source() {
    echo "*** Apt: update source"

    curl -fsSL https://mirrors.aliyun.com/kubernetes/apt/doc/apt-key.gpg | apt-key add -
    cat > /etc/apt/sources.list.d/kubernetes.list <<EOF
deb [arch=amd64] https://mirrors.aliyun.com/kubernetes/apt/ kubernetes-$(lsb_release -cs) main
EOF
    apt update
}

apt_install_k8s() {
    local version=`apt-cache madison kubelet|grep "$KUBE_VERSION"|head -n1|awk '{print $3}'`
    echo "*** Apt: install k8s: $version"

    apt install -y --allow-change-held-packages --allow-downgrades kubelet=$version kubeadm=$version kubectl=$version
    apt-mark hold kubelet kubeadm kubectl
    systemctl enable --now kubelet
}

kubelet_add_env_file() {
    echo "*** kubelet: Add 'EnvironmentFile'"

    local args=""
    if ! mount | grep -q "cgroup/pids"; then
        #LocalStorageCapacityIsolation=false
        #    - Failed to start ContainerManager failed to get rootfs info: unable to find data in memory cache
        #SupportPodPidsLimit=false,SupportNodePidsLimit=false
        #    - pid cgroup is supported after kernel 4.x
        args="--feature-gates=LocalStorageCapacityIsolation=false,SupportPodPidsLimit=false,SupportNodePidsLimit=false"
    fi
    cat > /etc/default/kubelet <<EOF
KUBELET_EXTRA_ARGS="$args --max-pods=300"
EOF
}

sys_udpate_kubelet_service() {
    echo "*** systemd: update service of k8s"

    systemd_svc="/etc/systemd/system/kubelet.service.d/"
    systemd_conf="$systemd_svc/10-kubeadm.conf"
    mkdir -p $systemd_svc
    [ ! -e $systemd_conf ] && cp /lib/systemd/system/kubelet.service.d/10-kubeadm.conf $systemd_conf
    if ! grep -q "User=root" $systemd_conf; then
        sed -i '/Service/a\User=root' $systemd_conf
    fi
}

apt_add_k8s_source
apt_install_k8s
kubelet_add_env_file
sys_udpate_kubelet_service

脚本要点：

通过 apt-mark hold 锁定版本，避免 kubelet 被意外升级。
老内核没有 pid cgroup 时，通过 --feature-gates 关闭相关特性。

2 方法二：单独安装 kubectl

下载最新稳定版本：

        
      
# 先获取最新版本号
curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt

# 下载指定版本
curl -LO https://storage.googleapis.com/kubernetes-release/release/v1.17.0/bin/linux/amd64/kubectl

# 添加可执行权限，移动到 /usr/local/bin
chmod +x ./kubectl
mv ./kubectl /usr/local/bin/kubectl

# 验证
kubectl version

通过包管理工具安装（apt）：

        
      
sudo apt-get update && sudo apt-get install -y apt-transport-https
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
echo "deb https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee -a /etc/apt/sources.list.d/kubernetes.list
sudo apt-get update
sudo apt-get install -y kubectl

3 安装 minikube（单节点本地环境）

        
      
curl -Lo minikube https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64
chmod +x minikube
mv minikube /usr/local/bin/

4 相关学习资源

官方入门教程：https://kubernetes.io/docs/tutorials/kubernetes-basics/
中文指南：https://jimmysong.io/kubernetes-handbook/
部署指南：https://ieevee.com/_book/

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