k8s(1)-使用kubeadm安装Kubernetes

安装前准备

1. 一台或多台主机，这里准备三台机器

角色	IP	Hostname	配置（最低）	操作系统版本
主节点	192.168.0.10	master	2核2G	CentOS7.6.1810
工作节点	192.168.0.11	node1	2核2G	CentOS7.6.1810
工作节点	192.168.0.12	node2	2核2G	CentOS7.6.1810

2. 验证MAC地址和product_uuid对于每个节点都是唯一的

您可以使用命令ip link或ifconfig -a获取网络接口的MAC地址
可以使用 sudo cat /sys/class/dmi/id/product_uuid 查看product_uuid

3. 检查所需端口

主节点

子节点

4. 所有节点同步时间

yum install ntpdate -y
ntpdate 0.asia.pool.ntp.org

5. 修改主机名，分别在三个节点下执行

hostnamectl set-hostname master
hostnamectl set-hostname node1
hostnamectl set-hostname node2

6. 在三个节点下修改hosts文件

192.168.0.10 master
192.168.0.11 node1
192.168.0.12 node2

7. 关闭所有节点的防火墙及SELinux

systemctl stop firewalld
systemctl disable firewalld
setenforce 0
sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

8. CentOS7需要确保确保 net.bridge.bridge-nf-call-iptables在sysctl配置中设置为1，在所有节点执行

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
vm.swappiness=0
EOF
sysctl --system

9. 关闭SWAP

swapoff -a

　注释掉/etc/fstab中的swap挂载那一行

安装Docker CE

yum remove docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate
yum install -y yum-utils device-mapper-persistent-data lvm2
yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
yum install docker-ce -y
systemctl start docker
systemctl enable docker

安装kubeadm，kubelet和kubectl

kubeadm：引导群集的命令。
kubelet：在群集中的所有计算机上运行的组件，并执行诸如启动pod和容器之类的操作。
kubectl：用于与群集通信的命令行util。

1. 编辑版本库

在每个节点执行

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[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

2. 安装，并设置kubelet开机自启动

yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetessystemctl enable kubelet && systemctl start kubelet

从安装结果可以看出还安装了cri-tools, kubernetes-cni, socat三个依赖：
　　官方从Kubernetes 1.9开始就将cni依赖升级到了0.6.0版本，在当前1.12中仍然是这个版本
　　socat是kubelet的依赖
　　cri-tools是CRI(Container Runtime Interface)容器运行时接口的命令行工具

创建集群

1. 初始化

kubeadm init \--pod-network-cidr=10.244.0.0/16 \--apiserver-advertise-address=192.168.0.10

　　参数解释注解：

　　　　为了flannel网络正常工作，你必须通过--pod-network-cidr=10.244.0.0/16

kubeadm使用与默认网关关联的网络接口来通告主IP，使用其他网络接口，请加上--apiserver-advertise-address=<ip-address>

初始化报错，镜像拉取错误，这是由于国内的防火墙测原因

error execution phase preflight: [preflight] Some fatal errors occurred:[ERROR ImagePull]: failed to pull image k8s.gcr.io/kube-apiserver:v1.13.0: output: Error response from daemon: Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
, error: exit status 1[ERROR ImagePull]: failed to pull image k8s.gcr.io/kube-controller-manager:v1.13.0: output: Error response from daemon: Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
, error: exit status 1[ERROR ImagePull]: failed to pull image k8s.gcr.io/kube-scheduler:v1.13.0: output: Error response from daemon: Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
, error: exit status 1[ERROR ImagePull]: failed to pull image k8s.gcr.io/kube-proxy:v1.13.0: output: Error response from daemon: Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
, error: exit status 1[ERROR ImagePull]: failed to pull image k8s.gcr.io/pause:3.1: output: Error response from daemon: Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
, error: exit status 1[ERROR ImagePull]: failed to pull image k8s.gcr.io/etcd:3.2.24: output: Error response from daemon: Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
, error: exit status 1[ERROR ImagePull]: failed to pull image k8s.gcr.io/coredns:1.2.6: output: Error response from daemon: Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
, error: exit status 1
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`

　　解决方法如下，这些镜像也应该下载到工作节点

 # 从dockerhub下载需要的镜像docker pull mirrorgooglecontainers/kube-apiserver:v1.13.2docker pull mirrorgooglecontainers/kube-controller-manager:v1.13.2docker pull mirrorgooglecontainers/kube-scheduler:v1.13.2docker pull mirrorgooglecontainers/kube-proxy:v1.13.2docker pull mirrorgooglecontainers/pause:3.1docker pull mirrorgooglecontainers/etcd:3.2.24docker pull coredns/coredns:1.2.6# 修改dockerhub镜像tag为k8s.gcr.iodocker tag docker.io/mirrorgooglecontainers/kube-apiserver:v1.13.2 k8s.gcr.io/kube-apiserver:v1.13.2docker tag docker.io/mirrorgooglecontainers/kube-controller-manager:v1.13.2 k8s.gcr.io/kube-controller-manager:v1.13.2docker tag docker.io/mirrorgooglecontainers/kube-scheduler:v1.13.2 k8s.gcr.io/kube-scheduler:v1.13.2docker tag docker.io/mirrorgooglecontainers/kube-proxy:v1.13.2 k8s.gcr.io/kube-proxy:v1.13.2docker tag docker.io/mirrorgooglecontainers/pause:3.1  k8s.gcr.io/pause:3.1docker tag docker.io/mirrorgooglecontainers/etcd:3.2.24  k8s.gcr.io/etcd:3.2.24docker tag docker.io/coredns/coredns:1.2.6  k8s.gcr.io/coredns:1.2.6# 删除多余镜像docker rmi mirrorgooglecontainers/kube-apiserver:v1.13.2docker rmi mirrorgooglecontainers/kube-controller-manager:v1.13.2docker rmi mirrorgooglecontainers/kube-scheduler:v1.13.2docker rmi mirrorgooglecontainers/kube-proxy:v1.13.2docker rmi mirrorgooglecontainers/pause:3.1docker rmi mirrorgooglecontainers/etcd:3.2.24docker rmi coredns/coredns:1.2.6

再次执行初始化，成功，日志如下，记录了完成的初始化输出的内容，根据输出的内容基本上可以看出手动初始化安装一个Kubernetes集群所需要的关键步骤。

[root@master ~]# kubeadm init \
>   --kubernetes-version=v1.13.0 \
>   --pod-network-cidr=10.244.0.0/16 \
>   --apiserver-advertise-address=192.168.0.10
[init] Using Kubernetes version: v1.13.0
[preflight] Running pre-flight checks[WARNING SystemVerification]: this Docker version is not on the list of validated versions: 18.09.1. Latest validated version: 18.06
[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 "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.0.10]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [master localhost] and IPs [192.168.0.10 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [master localhost] and IPs [192.168.0.10 127.0.0.1 ::1]
[certs] Generating "apiserver-etcd-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 30.506947 seconds
[uploadconfig] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.13" in namespace kube-system with the configuration for the kubelets in the cluster
[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "master" as an annotation
[mark-control-plane] Marking the node master as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: k9bohf.6zl3ovmlkf4iwudg
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstraptoken] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstraptoken] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstraptoken] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstraptoken] creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxyYour Kubernetes master has initialized successfully!To start using your cluster, you need to run the following as a regular user:mkdir -p $HOME/.kubesudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/configsudo chown $(id -u):$(id -g) $HOME/.kube/configYou 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/You can now join any number of machines by running the following on each node
as root:kubeadm join 192.168.0.10:6443 --token k9bohf.6zl3ovmlkf4iwudg --discovery-token-ca-cert-hash sha256:e73fe78ac9a961582a0ad81e3bffbebfa1d81b37b2f0cd7aacbfa6c1a1de351c

要使kubectl为非root用户工作，请运行以下命令，这些命令也是kubeadm init输出的一部分

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

　　或者，如果您是root用户，则可以运行：

export KUBECONFIG=/etc/kubernetes/admin.conf

2. 安装pod网络附加组件

这里选择flannel作为Pod的网络，在管理节点下执行

[root@master ~]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/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

安装了pod网络后，您可以通过运行下面命令检查CoreDNS pod是否正常工作

[root@master ~]# kubectl get pods --all-namespaces -o wide
NAMESPACE     NAME                             READY   STATUS    RESTARTS   AGE
kube-system   coredns-86c58d9df4-fvrfv         1/1     Running   0          17m
kube-system   coredns-86c58d9df4-lgsxd         1/1     Running   0          17m
kube-system   etcd-master                      1/1     Running   0          16m
kube-system   kube-apiserver-master            1/1     Running   0          16m
kube-system   kube-controller-manager-master   1/1     Running   0          16m
kube-system   kube-flannel-ds-amd64-h56rl      1/1     Running   0          92s
kube-system   kube-proxy-99hmp                 1/1     Running   0          17m
kube-system   kube-scheduler-master            1/1     Running   0          16m

　　如果报错，下面的方法排错：

查看日志： /var/log/messages

kubectl --namespace kube-system logs kube-flannel-ds-amd64-wdqsl

3. 加入工作节点

在工作节点执行初始化时日志的输出。

 kubeadm join 192.168.0.10:6443 --token qrduq2.24km2r56xg24o6yw --discovery-token-ca-cert-hash sha256:54c981ec4220202107b1ef89907d31af94840ed75a1e9f352f9288245760ac83

更新令牌

默认情况下令牌24小时过期，使用下面方法创建新的令牌

kubeadm token create
kubeadm token list

4. 查看节点的状态

状态为Ready表示和Master节点正常通信

[root@master ~]# kubectl get nodes
NAME     STATUS   ROLES    AGE    VERSION
master   Ready    master   104m   v1.13.2
node1    Ready    <none>   34m    v1.13.2
node2    Ready    <none>   29m    v1.13.2

5. 将主节点加入工作负载（可选操作）

默认情况下，出于安全原因，您的群集不会在主服务器上安排pod。如果您希望能够在主服务器上安排pod，例如，对于用于开发的单机Kubernetes集群，请运行：

[root@master ~]# kubectl describe node master | grep Taint
Taints:             node-role.kubernetes.io/master:NoSchedule
[root@master ~]# kubectl taint nodes --all node-role.kubernetes.io/master-
node/master untainted
taint "node-role.kubernetes.io/master:" not found
taint "node-role.kubernetes.io/master:" not found

6. 从主服务器以外的计算机控制您的群集（可选操作）

在工作节点上运行

scp root@<master ip>:/etc/kubernetes/admin.conf .
kubectl --kubeconfig ./admin.conf get nodes

移除集群

在控制节点上运行

kubectl drain <node name> --delete-local-data --force --ignore-daemonsets
kubectl delete node <node name>

　然后，在要删除的节点上，重置所有kubeadm安装状态：

kubeadm reset

　　重置过程不会重置或清除iptables规则或IPVS表。如果您想重置iptables，必须手动执行：

iptables -F && iptables -t nat -F && iptables -t mangle -F && iptables -X

　　如果要重置IPVS表，则必须运行以下命令：

ipvsadm -C

参考文档：https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/

转载于:https://www.cnblogs.com/zydev/p/10302639.html