K8S/Kubernetes

目录

• 2 安装kubelet
  • 2.1 环境准备
  • 2.2 设置国内的源
  • 2.3 重要的设置
  • 2.4 获取镜像
  • 2.5 使用kubeadm init初始化集群
  • 2.6 安装Pod Network
  • 2.7 测试集群DNS是否可用
  • 2.8 向集群中添加Node节点
  • 2.9 kube-proxy开启ipvs

国内不fq安装K8S一: 安装docker
国内不fq安装K8S二: 安装kubernet
国内不fq安装K8S三: 使用helm安装kubernet-dashboard
国内不fq安装K8S四: 安装过程中遇到的问题和解决方法

2 安装kubelet

2.1 环境准备

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

#关闭防火墙
$ systemctl stop firewalld
$ systemctl disable --now firewalld  

#设置iptables(略)

#安装kubelet kubeadm kubectl
$ yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

#开机启动kubelet
$ systemctl enable --now kubelet  

2.2 设置国内的源

ps: master、node节点都需要安装kubelet kubeadm kubectl。
官方的源是packages.cloud.google.com，国内访问不了,因此使用阿里云的源

$ 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

2.3 重要的设置

确认/etc/hosts(kub1和kub2时是自己写的,也可以写node1、node2之类,localhost不能删)

$ cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

kub1    192.168.15.174
kub2    192.168.15.175

创建/etc/sysctl.d/k8s.conf文件

$ cat <<EOF >  /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
EOF

安装必要组件

$ yum install -y bridge-utils.x86_64
#ipvsadm和ipset是为了方便查看ipvs的
$ yum install ipset
$ yum install ipvsadm

使配置生效

$ modprobe br_netfilter
$ sysctl -p /etc/sysctl.d/k8s.conf
$ sysctl --system  

关闭swap & 取消开机挂载swap

$ swapoff -a && sysctl -w vm.swappiness=0
$ sed -ri '/^[^#]*swap/s@^@#@' /etc/fstab

安装必要的内核模块

$ cat > /etc/sysconfig/modules/ipvs.modules <<EOF
#!/bin/bash
modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack_ipv4
EOF
$ chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4

modprobe之后可以用lsmod查看是否生效

2.4 获取镜像

列出需要的镜像

$ kubeadm config images list
W0809 11:32:51.518614   18214 version.go:98] could not fetch a Kubernetes version from the internet: unable to get URL "https://dl.k8s.io/release/stable-1.txt": Get https://dl.k8s.io/release/stable-1.txt: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
W0809 11:32:51.519080   18214 version.go:99] falling back to the local client version: v1.15.2
k8s.gcr.io/kube-apiserver:v1.15.2
k8s.gcr.io/kube-controller-manager:v1.15.2
k8s.gcr.io/kube-scheduler:v1.15.2
k8s.gcr.io/kube-proxy:v1.15.2
k8s.gcr.io/pause:3.1
k8s.gcr.io/etcd:3.3.10
k8s.gcr.io/coredns:1.3.1

说明：上段中提示连不上dl.k8s.io/：
我们fq访问一下：https://storage.googleapis.com/kubernetes-release/release/stable-1.txt发现也是:v1.15.2

### 从亚马逊获取镜像(国内可以访问,而且速度不慢)
docker pull gcr.azk8s.cn/google_containers/kube-apiserver:v1.15.2
docker pull gcr.azk8s.cn/google_containers/kube-controller-manager:v1.15.2
docker pull gcr.azk8s.cn/google_containers/kube-scheduler:v1.15.2
docker pull gcr.azk8s.cn/google_containers/kube-proxy:v1.15.2
docker pull gcr.azk8s.cn/google_containers/pause:3.1
docker pull gcr.azk8s.cn/google_containers/etcd:3.3.10
docker pull gcr.azk8s.cn/google_containers/coredns:1.3.1

# 将镜像打Tag成目标镜像
docker tag gcr.azk8s.cn/google_containers/kube-proxy:v1.15.2 k8s.gcr.io/kube-proxy:v1.15.2
docker tag gcr.azk8s.cn/google_containers/kube-controller-manager:v1.15.2  k8s.gcr.io/kube-controller-manager:v1.15.2
docker tag gcr.azk8s.cn/google_containers/kube-scheduler:v1.15.2 k8s.gcr.io/kube-scheduler:v1.15.2
docker tag gcr.azk8s.cn/google_containers/kube-apiserver:v1.15.2  k8s.gcr.io/kube-apiserver:v1.15.2
docker tag gcr.azk8s.cn/google_containers/coredns:1.3.1  k8s.gcr.io/coredns:1.3.1
docker tag gcr.azk8s.cn/google_containers/etcd:3.3.10  k8s.gcr.io/etcd:3.3.10
docker tag gcr.azk8s.cn/google_containers/pause:3.1  k8s.gcr.io/pause:3.1

# 删除下载的镜像
docker rmi gcr.azk8s.cn/google_containers/kube-apiserver:v1.15.2
docker rmi gcr.azk8s.cn/google_containers/kube-controller-manager:v1.15.2
docker rmi gcr.azk8s.cn/google_containers/kube-scheduler:v1.15.2
docker rmi gcr.azk8s.cn/google_containers/kube-proxy:v1.15.2
docker rmi gcr.azk8s.cn/google_containers/pause:3.1
docker rmi gcr.azk8s.cn/google_containers/etcd:3.3.10
docker rmi gcr.azk8s.cn/google_containers/coredns:1.3.1

2.5 使用kubeadm init初始化集群

查看集群的默认配置

$ kubeadm config print init-defaults
结果(略)

使用kubeadm默认配置初始化的集群，会在master节点打上node-role.kubernetes.io/master:NoSchedule的污点，阻止master节点接受调度运行工作负载。这里测试环境只有两个节点，所以将这个taint修改为node-role.kubernetes.io/master:PreferNoSchedule。

根据上面的结果编辑yaml文件

$ vi kubeadm.yaml
apiVersion: kubeadm.k8s.io/v1beta2
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 192.168.15.174
  bindPort: 6443
nodeRegistration:
  taints:
  - effect: PreferNoSchedule
    key: node-role.kubernetes.io/master
---
apiVersion: kubeadm.k8s.io/v1beta2
kind: ClusterConfiguration
kubernetesVersion: v1.15.2 
networking:
  podSubnet: 10.244.0.0/16

初始化

$ kubeadm init --config kubeadm.yaml --ignore-preflight-errors=Swap
[init] Using Kubernetes version: v1.15.2
[preflight] Running pre-flight checks
    [WARNING Hostname]: hostname "kub1" could not be reached
    [WARNING Hostname]: hostname "kub1": lookup kub1 on 114.114.114.114:53: no such host
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [kub1 localhost] and IPs [192.168.15.174 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [kub1 localhost] and IPs [192.168.15.174 127.0.0.1 ::1]
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [kub1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.15.174]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 39.505847 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.15" in namespace kube-system with the configuration for the kubelets in the cluster
[kubelet-check] Initial timeout of 40s passed.
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node kub1 as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node kub1 as control-plane by adding the taints [node-role.kubernetes.io/master:PreferNoSchedule]
[bootstrap-token] Using token: xzmioa.hnr8r2qrghsr9xje
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

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 192.168.15.174:6443 --token xzmioa.hnr8r2qrghsr9xje \
    --discovery-token-ca-cert-hash sha256:779d4c9330409f67b584f36baf2e882c42ac9d6c9e2c3765904c341fb3b89d10 

按提示设置

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

查看一下集群状态，确认个组件都处于healthy状态：

$ kubectl get cs
NAME                 STATUS    MESSAGE             ERROR
scheduler            Healthy   ok                  
controller-manager   Healthy   ok                  
etcd-0               Healthy   {"health":"true"}   

如果kubeadm init不成功,执行下面的命令重置

$ kubeadm reset
$ ifconfig cni0 down
$ ip link delete cni0
$ ifconfig flannel.1 down
$ ip link delete flannel.1
$ rm -rf /var/lib/cni/

2.6 安装Pod Network

$ curl -O https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
$ kubectl apply -f  kube-flannel.yml
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created

如果node有多个网卡,需编辑kube-flannel.yml,用--iface指定网卡

......
containers:
      - name: kube-flannel
        image: quay.io/coreos/flannel:v0.11.0-amd64
        command:
        - /opt/bin/flanneld
        args:
        - --ip-masq
        - --kube-subnet-mgr
        - --iface=eth1
......

查看状态(必须保证所有pod都Running)

$ kubectl get pod -n kube-system
NAME                            READY   STATUS    RESTARTS   AGE
coredns-5c98db65d4-dr8lf        1/1     Running   0          52m
coredns-5c98db65d4-lp8dg        1/1     Running   0          52m
etcd-node1                      1/1     Running   0          51m
kube-apiserver-node1            1/1     Running   0          51m
kube-controller-manager-node1   1/1     Running   0          51m
kube-flannel-ds-amd64-mm296     1/1     Running   0          44s
kube-proxy-kchkf                1/1     Running   0          52m
kube-scheduler-node1            1/1     Running   0          51m

2.7 测试集群DNS是否可用

确保coredns运行正常后,启动一个虚拟机测试

$ kubectl run curl --image=radial/busyboxplus:curl -it
kubectl run --generator=deployment/apps.v1beta1 is DEPRECATED and will be removed in a future version. Use kubectl create instead.
If you don't see a command prompt, try pressing enter.
[ root@curl-5cc7b478b6-r997p:/ ]$ nslookup kubernetes.default
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes.default
Address 1: 10.96.0.1 kubernetes.default.svc.cluster.local

nslookup kubernetes.default是在pod中运行的。

2.8 向集群中添加Node节点

在其他节点上执行kubeadm join(这个命令就是主节点kubeadm init打印出来的)

$ kubeadm join 192.168.15.174:6443 --token xzmioa.hnr8r2qrghsr9xje \
    --discovery-token-ca-cert-hash sha256:779d4c9330409f67b584f36baf2e882c42ac9d6c9e2c3765904c341fb3b89d10 

查看集群中所有节点：

$ kubectl get node
NAME   STATUS   ROLES         AGE     VERSION
kub1   Ready    master        5h51m   v1.15.2
kub2   Ready    <none>        5h44m   v1.15.2

2.9 kube-proxy开启ipvs

将配置中的“mode " " ”改成“mode "ipvs"”

$ kubectl edit cm kube-proxy -n kube-system
.......
    ipvs:
      excludeCIDRs: null
      minSyncPeriod: 0s
      scheduler: ""
      strictARP: false
      syncPeriod: 30s
    kind: KubeProxyConfiguration
    metricsBindAddress: 127.0.0.1:10249
    mode: "ipvs"
    nodePortAddresses: null
    oomScoreAdj: -999
......

重启kube-proxy 的 pod

$ kubectl get pod -n kube-system | grep kube-proxy | awk '{system("kubectl delete pod "$1" -n kube-system")}'

查看ipvs是否成功

$ kubectl get pod -n kube-system | grep kube-proxy
kube-proxy-7fsrg                1/1     Running   0          3s
kube-proxy-k8vhm                1/1     Running   0          9s

$ kubectl logs kube-proxy-7fsrg  -n kube-system
I0703 04:42:33.308289       1 server_others.go:170] Using ipvs Proxier.
....

如果不成功kubectl logs会显示出Using iptables，可以看到有两个kube-proxy pod，如果其中有一个没成功，很有可能是有一个节点上没有执行“/etc/sysconfig/modules/ipvs.modules”那一步。