搭建K8s集群

官网：https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/#installing-kubeadm-kubelet-and-kubectl

GitHub：https://github.com/kubernetes/kubeadm

使用kubeadm搭建一个3台机器组成的k8s集群，1台master节点，2台worker节点

如果大家机器配置不够，也可以使用在线的，或者minikube的方式或者1个master和1个worker

配置要求：

• One or more machines running one of:
  • Ubuntu 16.04+
  • Debian 9+
  • CentOS 7【课程中使用】
  • Red Hat Enterprise Linux (RHEL) 7
  • Fedora 25+
  • HypriotOS v1.0.1+
  • Container Linux (tested with 1800.6.0)
• 2 GB or more of RAM per machine (any less will leave little room for your apps)
• 2 CPUs or more
• Full network connectivity between all machines in the cluster (public or private network is fine)
• Unique hostname, MAC address, and product_uuid for every node. See here for more details.
• Certain ports are open on your machines. See here for more details.
• Swap disabled. You MUST disable swap in order for the kubelet to work properly.

1.1 版本统一

Docker       18.09.0
---
kubeadm-1.14.0-0 
kubelet-1.14.0-0 
kubectl-1.14.0-0
---
k8s.gcr.io/kube-apiserver:v1.14.0
k8s.gcr.io/kube-controller-manager:v1.14.0
k8s.gcr.io/kube-scheduler:v1.14.0
k8s.gcr.io/kube-proxy:v1.14.0
k8s.gcr.io/pause:3.1
k8s.gcr.io/etcd:3.3.10
k8s.gcr.io/coredns:1.3.1
---
calico:v3.9

1.2 准备3台centos

大家根据自己的情况来准备centos7的虚拟机。

要保证彼此之间能够ping通，也就是处于同一个网络中，虚拟机的配置要求上面也描述。

1.3 更新并安装依赖

3台机器都需要执行

yum -y update
yum install -y conntrack ipvsadm ipset jq sysstat curl iptables libseccomp

1.4 安装Docker

在每一台机器上都安装好Docker，版本为18.09.0

指定安装docker版本：yum install -y docker-ce-18.09.0 docker-ce-cli-18.09.0 containerd.io

1.5 修改hosts文件

(1)master

# 设置master的hostname，并且修改hosts文件
sudo hostnamectl set-hostname m

vi /etc/hosts
192.168.8.51 m
192.168.8.61 w1
192.168.8.62 w2

(2)两个worker

# 设置worker01/02的hostname，并且修改hosts文件
sudo hostnamectl set-hostname w1
sudo hostnamectl set-hostname w2

vi /etc/hosts
192.168.8.51 m
192.168.8.61 w1
192.168.8.62 w2

(3)使用ping测试一下

1.6 系统基础前提配置

# (1)关闭防火墙
systemctl stop firewalld && systemctl disable firewalld

# (2)关闭selinux
setenforce 0
sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

# (3)关闭swap
swapoff -a
sed -i '/swap/s/^(.*)$/#1/g' /etc/fstab

# (4)配置iptables的ACCEPT规则
iptables -F && iptables -X && iptables -F -t nat && iptables -X -t nat && iptables -P FORWARD ACCEPT

# (5)设置系统参数
cat <<EOF >  /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF

sysctl --system

1.7 Installing kubeadm, kubelet and kubectl

(1)配置yum源

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
       http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

(2)安装kubeadm&kubelet&kubectl

yum install -y kubeadm-1.14.0-0 kubelet-1.14.0-0 kubectl-1.14.0-0

(3)docker和k8s设置同一个cgroup

# docker
vi /etc/docker/daemon.json
    "exec-opts": ["native.cgroupdriver=systemd"],
    
systemctl restart docker
    
# kubelet
sed -i "s/cgroup-driver=systemd/cgroup-driver=cgroupfs/g" /etc/systemd/system/kubelet.service.d/10-kubeadm.conf
	
systemctl enable kubelet && systemctl start kubelet

1.8 proxy/pause/scheduler等国内镜像

(1)查看kubeadm使用的镜像

kubeadm config images list

可以发现这里都是国外的镜像

k8s.gcr.io/kube-apiserver:v1.14.0
k8s.gcr.io/kube-controller-manager:v1.14.0
k8s.gcr.io/kube-scheduler:v1.14.0
k8s.gcr.io/kube-proxy:v1.14.0
k8s.gcr.io/pause:3.1
k8s.gcr.io/etcd:3.3.10
k8s.gcr.io/coredns:1.3.1

(2)解决国外镜像不能访问的问题

• 创建kubeadm.sh脚本，用于拉取镜像/打tag/删除原有镜像

#!/bin/bash

set -e

KUBE_VERSION=v1.14.0
KUBE_PAUSE_VERSION=3.1
ETCD_VERSION=3.3.10
CORE_DNS_VERSION=1.3.1

GCR_URL=k8s.gcr.io
ALIYUN_URL=registry.cn-hangzhou.aliyuncs.com/google_containers

images=(kube-proxy:${KUBE_VERSION}
kube-scheduler:${KUBE_VERSION}
kube-controller-manager:${KUBE_VERSION}
kube-apiserver:${KUBE_VERSION}
pause:${KUBE_PAUSE_VERSION}
etcd:${ETCD_VERSION}
coredns:${CORE_DNS_VERSION})

for imageName in ${images[@]} ; do
  docker pull $ALIYUN_URL/$imageName
  docker tag  $ALIYUN_URL/$imageName $GCR_URL/$imageName
  docker rmi $ALIYUN_URL/$imageName
done

• 运行脚本和查看镜像

# 运行脚本
sh ./kubeadm.sh

# 查看镜像
docker images

• 将这些镜像推送到自己的阿里云仓库【可选，根据自己实际的情况】

# 登录自己的阿里云仓库
docker login --username=xxx registry.cn-hangzhou.aliyuncs.com

#!/bin/bash

set -e

KUBE_VERSION=v1.14.0
KUBE_PAUSE_VERSION=3.1
ETCD_VERSION=3.3.10
CORE_DNS_VERSION=1.3.1

GCR_URL=k8s.gcr.io
ALIYUN_URL=xxx

images=(kube-proxy:${KUBE_VERSION}
kube-scheduler:${KUBE_VERSION}
kube-controller-manager:${KUBE_VERSION}
kube-apiserver:${KUBE_VERSION}
pause:${KUBE_PAUSE_VERSION}
etcd:${ETCD_VERSION}
coredns:${CORE_DNS_VERSION})

for imageName in ${images[@]} ; do
  docker tag $GCR_URL/$imageName $ALIYUN_URL/$imageName
  docker push $ALIYUN_URL/$imageName
  docker rmi $ALIYUN_URL/$imageName
done

运行脚本 sh ./kubeadm-push-aliyun.sh

1.9 kube init初始化master

(1)kube init流程

01-进行一系列检查，以确定这台机器可以部署kubernetes

02-生成kubernetes对外提供服务所需要的各种证书可对应目录
/etc/kubernetes/pki/*

03-为其他组件生成访问kube-ApiServer所需的配置文件
    ls /etc/kubernetes/
    admin.conf  controller-manager.conf  kubelet.conf  scheduler.conf
    
04-为 Master组件生成Pod配置文件。
    ls /etc/kubernetes/manifests/*.yaml
    kube-apiserver.yaml 
    kube-controller-manager.yaml
    kube-scheduler.yaml
    
05-生成etcd的Pod YAML文件。
    ls /etc/kubernetes/manifests/*.yaml
    kube-apiserver.yaml 
    kube-controller-manager.yaml
    kube-scheduler.yaml
	etcd.yaml
	
06-一旦这些 YAML 文件出现在被 kubelet 监视的/etc/kubernetes/manifests/目录下，kubelet就会自动创建这些yaml文件定义的pod，即master组件的容器。master容器启动后，kubeadm会通过检查localhost：6443/healthz这个master组件的健康状态检查URL，等待master组件完全运行起来

07-为集群生成一个bootstrap token

08-将ca.crt等 Master节点的重要信息，通过ConfigMap的方式保存在etcd中，工后续部署node节点使用

09-最后一步是安装默认插件，kubernetes默认kube-proxy和DNS两个插件是必须安装的

(2)初始化master节点

官网：https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm/

注意：此操作是在主节点上进行

# 本地有镜像
kubeadm init --kubernetes-version=1.14.0 --apiserver-advertise-address=192.168.3.160 --pod-network-cidr=10.244.0.0/16
【若要重新初始化集群状态：kubeadm reset，然后再进行上述操作】

记得保存好最后kubeadm join的信息

(3)根据日志提示

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

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

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.3.160:6443 --token zt2df2.v866n2bw2pyjyq1o 
    --discovery-token-ca-cert-hash sha256:9537b7e84fab63dfa10bf5710563bd762c25ec184f288c4bce5818c71fef0183

此时kubectl cluster-info查看一下是否成功

(4)查看pod验证一下

等待一会儿，同时可以发现像etc，controller，scheduler等组件都以pod的方式安装成功了

注意：coredns没有启动，需要安装网络插件

kubectl get pods -n kube-system

(5)健康检查

curl -k https://localhost:6443/healthz

1.10 部署calico网络插件

选择网络插件：https://kubernetes.io/docs/concepts/cluster-administration/addons/

calico网络插件：https://docs.projectcalico.org/v3.9/getting-started/kubernetes/

calico，同样在master节点上操作

# 在k8s中安装calico
kubectl apply -f https://docs.projectcalico.org/v3.9/manifests/calico.yaml

# 确认一下calico是否安装成功
kubectl get pods --all-namespaces -w

1.11 kube join

记得保存初始化master节点的最后打印信息【注意这边大家要自己的，下面我的只是一个参考】

kubeadm join 192.168.0.51:6443 --token yu1ak0.2dcecvmpozsy8loh 
    --discovery-token-ca-cert-hash sha256:5c4a69b3bb05b81b675db5559b0e4d7972f1d0a61195f217161522f464c307b0

(1)在woker01和worker02上执行上述命令

(2)在master节点上检查集群信息

kubectl get nodes

NAME                   STATUS   ROLES    AGE     VERSION
master-kubeadm-k8s     Ready    master   19m     v1.14.0
worker01-kubeadm-k8s   Ready    <none>   3m6s    v1.14.0
worker02-kubeadm-k8s   Ready    <none>   2m41s   v1.14.0

1.12 再次体验Pod

(1)定义pod.yml文件，比如pod_nginx_rs.yaml

cat > pod_nginx_rs.yaml <<EOF
apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: nginx
  labels:
    tier: frontend
spec:
  replicas: 3
  selector:
    matchLabels:
      tier: frontend
  template:
    metadata:
      name: nginx
      labels:
        tier: frontend
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
EOF

(2)根据pod_nginx_rs.yml文件创建pod

kubectl apply -f pod_nginx_rs.yaml

(3)查看pod

kubectl get pods
kubectl get pods -o wide
kubectl describe pod nginx

(4)感受通过rs将pod扩容

kubectl scale rs nginx --replicas=5
kubectl get pods -o wide

(5)删除pod

kubectl delete -f pod_nginx_rs.yaml