kubernetes环境搭建

安装方式

• minikube：一个用于快速搭建单节点kubernets的工具
• kubeadm：用于快速搭建kubernets集群的工具
• 二进制包：从官网上下载每一个组件的二进制包，依次去安装，更容易理解kubernets的组件

环境规划 Centos7

master: 192.168.248.10 2核2G

node1: 192.168.248.11 2核2G

node2: 192.168.248.12 2核2G

 

以下3台都需要配置

1.配置hosts文件

2.关闭防火墙selinux
 setenforce 0
 sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config

3.时间同步
#master节点
vim /etc/chrony.conf
server ntp1.aliyun.com iburst 
allow 192.168.168.0/24 
systemctl restart chronyd 
#node节点 
vim /etc/chrony.conf 
server 192.168.248.10 iburst 
systemctl restart chronyd


4.关闭sawp分区
swapoff -a
注释掉 /etc/fstab 文件中的 swap配置

5.修改内核参数
vim /etc/sysctl.d/kubernetes.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1

#重载配置
sysctl -p 

#加载网桥过滤模块
modprobe br_netfilter

#查看网桥过滤模块是否加载成功
lsmod | grep br_netfilter

6.配置ipvs功能
在kubernetes中service有两种代理模型，一种基于iptables，一种基于ipvs，两者相比ipvs性能明显要高一些，如果需要使用要手动载入ipvs模块
yum -y install ipset ipvsadm

cat  <<EOF >  /etc/sysconfig/modules/ipvs.modules
#!/bin/bash
modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack_ipv4
EOF

chmod +x /etc/sysconfig/modules/ipvs.modules

/bin/bash /etc/sysconfig/modules/ipvs.modules

lsmod | grep -e ip_vs -e nf_conntrack_ipv4

7.重启服务器

安装docker

#安装docker源
cd /etc/yum.repos.d/
curl -o docker-ce.repo https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/docker-ce.repo

# 查看镜像源中所支持的docker版本
yum list docker-ce --showduplicates

# 安装特定版本的docker-ce
# 必须指定 --setopt=obsoletes=0，否则yum会自动安装更高的版本
yum -y install --setopt=onsoletes=0 docker-ce-18.06.3.ce-3.el7


# 添加配置文件，docker在默认情况下使用Cgroup Driver为cgroupfs,而kubernets推荐使用systemd来代替cgroupfs
mkdir /etc/docker

cat <<EOF > /etc/docker/daemon.json
{
    "exec-opts" : ["native.cgroupdriver=systemd"],
    "registry-mirrors" : ["https://kn0t2bca.mirror.aliyuncs.com"]
}
EOF

#启动docker
systemctl start docker 
systemctl enable docker

安装kubernetes组件

#切换到国内镜像源
vim /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
         
#安装kubeadm、kubelet和kubectl
yum -y install --setopt=obsoletes=0 kubeadm-1.17.4-0 kubelet-1.17.4-0 kubectl-1.17.4-0

#配置kubelet的cgroup
vim /etc/sysconfig/kubelet
KUBELET_CGROUP_ARGS="--cgroup-driver=systemd"
KUBE_PROXY_MODE="ipvs"

#设置kubelet开机自启
systemctl enable kubelet

准备集群镜像

# 在安装kubernetes集群之前，必须提前准备好集群需要的镜像，可以通过以下命令查看
kubeadm config images list

#下载镜像
#此镜像在kubernetes的仓库中，由于网络原因，无法连接，下面通过了一种方法代替
images=(
    kube-apiserver:v1.17.4
    kube-controller-manager:v1.17.4
    kube-scheduler:v1.17.4
    kube-proxy:v1.17.4
    pause:3.1
    etcd:3.4.3-0
    coredns:1.6.5
)

for imageName in ${images[@]};do 
    docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/$imageName
    docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/$imageName k8s.gcr.io/$imageName
    docker rmi registry.cn-hangzhou.aliyuncs.com/google_containers/$imageName
done

集群初始化

下面操作只需要在master上执行即可

#创建集群
[root@master ~]# kubeadm init --kubernetes-version=v1.17.4 --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12 --apiserver-advertise-address=192.168.248.10
.............

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 192.168.248.10:6443 --token epdgo0.xui34va7u2yfppmx 
    --discovery-token-ca-cert-hash sha256:85b336094393db232206802247c4b09b20ee9dab5c2fe4cca841d00e605a6d8b 
#将node节点加入集群
[root@node1 ~]# kubeadm join 192.168.248.10:6443 --token epdgo0.xui34va7u2yfppmx     --discovery-token-ca-cert-hash sha256:85b336094393db232206802247c4b09b20ee9dab5c2fe4cca841d00e605a6d8b
[root@node2 ~]# kubeadm join 192.168.248.10:6443 --token epdgo0.xui34va7u2yfppmx     --discovery-token-ca-cert-hash sha256:85b336094393db232206802247c4b09b20ee9dab5c2fe4cca841d00e605a6d8b

# 创建必要的文件
mkdir -p $HOME/.kube
cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
chown $(id -u):$(id -g) $HOME/.kube/config

#查看node信息
[root@master ~]# kubectl  get node
NAME     STATUS     ROLES    AGE   VERSION
master   NotReady   master   95s   v1.17.4
node1    NotReady   <none>   38s   v1.17.4
node2    NotReady   <none>   34s   v1.17.4

安装网络插件

kubernetes支持多种网络插件，比如flannel、calico、canal等，本次使用flannel

# 下面还是在master节点执行即可，插件使用的事DaemonSet的控制器，它会在每个节点上运行

# 获取fannel的配置文件
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

如果下载不到的报错 连接失败,可以直接使用
vi  kube-flannel.yml
---
apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
  name: psp.flannel.unprivileged
  annotations:
    seccomp.security.alpha.kubernetes.io/allowedProfileNames: docker/default
    seccomp.security.alpha.kubernetes.io/defaultProfileName: docker/default
    apparmor.security.beta.kubernetes.io/allowedProfileNames: runtime/default
    apparmor.security.beta.kubernetes.io/defaultProfileName: runtime/default
spec:
  privileged: false
  volumes:
  - configMap
  - secret
  - emptyDir
  - hostPath
  allowedHostPaths:
  - pathPrefix: "/etc/cni/net.d"
  - pathPrefix: "/etc/kube-flannel"
  - pathPrefix: "/run/flannel"
  readOnlyRootFilesystem: false
  # Users and groups
  runAsUser:
    rule: RunAsAny
  supplementalGroups:
    rule: RunAsAny
  fsGroup:
    rule: RunAsAny
  # Privilege Escalation
  allowPrivilegeEscalation: false
  defaultAllowPrivilegeEscalation: false
  # Capabilities
  allowedCapabilities: ['NET_ADMIN', 'NET_RAW']
  defaultAddCapabilities: []
  requiredDropCapabilities: []
  # Host namespaces
  hostPID: false
  hostIPC: false
  hostNetwork: true
  hostPorts:
  - min: 0
    max: 65535
  # SELinux
  seLinux:
    # SELinux is unused in CaaSP
    rule: 'RunAsAny'
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: flannel
rules:
- apiGroups: ['extensions']
  resources: ['podsecuritypolicies']
  verbs: ['use']
  resourceNames: ['psp.flannel.unprivileged']
- apiGroups:
  - ""
  resources:
  - pods
  verbs:
  - get
- apiGroups:
  - ""
  resources:
  - nodes
  verbs:
  - list
  - watch
- apiGroups:
  - ""
  resources:
  - nodes/status
  verbs:
  - patch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
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
---
kind: ConfigMap
apiVersion: v1
metadata:
  name: kube-flannel-cfg
  namespace: kube-system
  labels:
    tier: node
    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:
    tier: node
    app: flannel
spec:
  selector:
    matchLabels:
      app: flannel
  template:
    metadata:
      labels:
        tier: node
        app: flannel
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: kubernetes.io/os
                operator: In
                values:
                - linux
      hostNetwork: true
      priorityClassName: system-node-critical
      tolerations:
      - operator: Exists
        effect: NoSchedule
      serviceAccountName: flannel
      initContainers:
      - name: install-cni
        image: quay.io/coreos/flannel:v0.13.1-rc1
        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: kube-flannel
        image: quay.io/coreos/flannel:v0.13.1-rc1
        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", "NET_RAW"]
        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: kube-flannel-cfg



# 使用配置文件启动flannel
[root@master ~]# kubectl apply  -f kube-flannel.yml

# 稍等一会在次查看集群
[root@master ~]# kubectl  get node
NAME     STATUS   ROLES    AGE     VERSION
master   Ready    master   8m56s   v1.17.4
node1    Ready    <none>   8m34s   v1.17.4
node2    Ready    <none>   3m52s   v1.17.4

集群测试

# 创建一个nginx服务
kubectl create deployment nginx --image=nginx:1.14-alpine

# 暴露端口 --type=NodePort让集群之外的浏览器可以访问
kubectl expose deploy nginx --port=80 --target-port=80 --type=NodePort

kubectl  get pod,svc
NAME                         READY   STATUS    RESTARTS   AGE
pod/nginx-6867cdf567-lh6vv   1/1     Running   1          9h

NAME                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
service/kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP        11h
service/nginx        NodePort    10.111.120.209   <none>        80:30317/TCP   9h

访问浏览器  nodeip:30317

资源管理

#命令式对象管理：直接使用命令去操作kubernets资源
kubectl run nginx-pod --image=nginx1.17.1 --pord=80

#命令式对象配置：通过命令配置和配置文件去操作kubernetes资源
kubectl create/patch -f nginx-pod.yml

#声明式对象配置：通过apply命令和配置文件去操作kubernetes资源
kubectl apply -f nginx-pod.yml
 

命令式对象管理

• kubectl命令

  kubectl式kubernetes集群的命令行工具，通过它能够对集群本身进行管理，并能够在集群上进行容器化安装部署。kubectl命令语法

kubectl [command] [type] [name] [flags

command: 指定要对资源执行的操作，例如create,get,delete

type: 指定资源类型，比如deployment、pod、service

name: 指定资源名称，名称大小写敏感

flags: 指定额外的可选参数

# 查看所有pod
kubectl get pod

# 查看某个pod
kubectl get pod pod_name

# 产看某一个pod，以yaml格式展示结果
kubectl get pod pod_name -o yaml

下面以一个namespace/pod的创建和删除简单演示一下命令的使用

#创建一个namespace
kubectl create namespace dev

#获取namespace
kubectl get ns
NAME              STATUS   AGE
default           Active   17h
dev               Active   12s
kube-node-lease   Active   17h
kube-public       Active   17h
kube-system       Active   17h

#在dev下创建一个nginx的pod
kubectl run pod --image=nginx -n dev

#查看新创建的pod
kubectl get pod -n dev
NAME                   READY   STATUS    RESTARTS   AGE
pod-864f9875b9-4htwm   1/1     Running   0          50s

#删除指定pod
kubectl delete pod pod-864f9875b9-4htwm -n dev

#删除指定namespace
kubectl delete ns dev

命令式对象配置

命令式对象配置就是使用命令配合配置文件一起来操作kubernetes资源

1）. 创建一个nginxpod.yml，内容如下

aipVersion: v1
kind: Namespace
metadata:
  name: dev
  
---
apiVersion: v1
kind: Pod
metadata:
  name: nginxpod
  namespace: dev
spec:
  containers:
  - name: nginx-containers
    image: nginx:1.17.1

 2）.执行create命令，创建资源：

kubectl create -f nginxpod.yml

 3）.执行get命令查看资源，发现创建了2个资源

kubectl  get -f nginxpod.yml 
NAME            STATUS   AGE
namespace/dev   Active   54s

NAME           READY   STATUS    RESTARTS   AGE
pod/nginxpod   1/1     Running   0          53s

 4）.执行delete命令删除资源

kubectl delete -f nginxpod.yml

 命令式对象配置的操作资源，可以简单的认为： 命令 + yml配置文件（里面的命令需要各种参数）

声明式对象配置

声明式对象配置和命令式对象配置很相似，但是它只有一个命令apply

# 首先执一次kubectl apply -f nginxpod.yml发现创建了资源
kubectl apply -f nginxpod.yml
namespace/dev created
pod/nginxpod created

#再次执行，发现资源没有变动
kubectl apply -f nginxpod.yml
namespace/dev unchanged
pod/nginxpod unchanged

其实声明式对象配置就是使用apply描叙一个资源的最终状态（在yml中定义状态），使用apply操作资源：

如果资源不存在则创建,相当于kubectl create 如果资源存在则更新，相当于kubectl patch

扩展： kubcetl可以在node节点上运行吗？

kubect的运行是需要进行配置的，它的配置文件￥HOME/.kube,如果想要在node节点运行此命令，需要将master上的。kube文件复制到node节点上，即在master节点执行以下操作即可

scp -r HOME/.kube  node:HOME/