使用kubeadm配置kubernetes（v1.17.4）环境

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1. 基础环境配置

1.1 主机域名解析

分别在master node和client node的/etc/hosts文件中，添加以下内容：

192.168.1.10 master master
192.168.1.11 client client

其中两个ip地址替换为上一篇中我们为两个虚机设置的‘host only’网络地址。

修改后：

1. master node

[root@master ~]# cat /etc/hosts
127.0.0.1   master localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

192.168.1.10 master master
192.168.1.11 client clien

2. client node

[root@client ~]# cat /etc/hosts
127.0.0.1   client localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

192.168.1.10 master master
192.168.1.11 client client

1.2 关闭防火墙服务

为了避免不必要的麻烦，我们将防火墙关闭。

分别在master node和client node上关闭firewalld。

1. master node

[root@master ~]# systemctl stop firewalld.servic
[root@master ~]# systemctl disable firewalld.service
Removed symlink /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.

2. client node

[root@client ~]# systemctl stop firewalld.servic
[root@client ~]# systemctl disable firewalld.service
Removed symlink /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.

1.3 关闭禁用SELinux

若当前系统启用了SELinux，则需要临时设置其当前状态为permissive：

1. master node

[root@master ~]# setenforce 0

2. client node

[root@client ~]# setenforce 0

另外修改/etc/sysconfig/selinux文件中的SELINUX值为disabled以彻底禁用SELinux：

1. master node修改后：

[root@master ~]# cat /etc/sysconfig/selinux

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#     enforcing - SELinux security policy is enforced.
#     permissive - SELinux prints warnings instead of enforcing.
#     disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of three values:
#     targeted - Targeted processes are protected,
#     minimum - Modification of targeted policy. Only selected processes are protected. 
#     mls - Multi Level Security protection.
SELINUXTYPE=targeted

2. client node修改后：

[root@client ~]# cat /etc/sysconfig/selinux

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#     enforcing - SELinux security policy is enforced.
#     permissive - SELinux prints warnings instead of enforcing.
#     disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of three values:
#     targeted - Targeted processes are protected,
#     minimum - Modification of targeted policy. Only selected processes are protected. 
#     mls - Multi Level Security protection.
SELINUXTYPE=targeted

2. 部署kubernetes集群

2.1 安装容器运行环境–docker

做完准备工作后，我们现在就可以开始部署kubernetes集群了。kubernetes支持多种容器运行环境，本文使用最流行的docker技术。

1. master node

[root@master ~]# wget https://download.docker.com/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo
[root@master ~]# yum install docker-ce -y

2. client node

[root@client ~]# wget https://download.docker.com/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo
[root@client ~]# yum install docker-ce -y

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Note:
如果系统没有安装wget，使用下面命令安装wget。

yum install wget -y

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安装完成后，我们需要修改iptables的FORWARD策略为ACCEPT，修改方法是修改/usr/lib/systemd/system/docker.service文件，在"ExecStart=/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock"之后加入一行内容（master node和client node都需要加）：

ExecStartPost=/usr/sbin/iptables -P FORWARD ACCEPT

然后我们重启docker服务，并设置docker为开机自启动：

1. master node

[root@master ~]# systemctl daemon-reload
[root@master ~]# systemctl start docker.service
[root@master ~]# systemctl enable docker.service
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.

2. clinet node

[root@client ~]# systemctl daemon-reload
[root@client ~]# systemctl start docker.service
[root@client ~]# systemctl enable docker.service
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.

2.2 设置kubernetes集群节点

2.2.1 安装kubelet和kubeadm

首先在master node和client node上分别添加用于安装kubelet和kubeadm，kubectl等组件的yum仓库，在master node和client node中分别添加文件"/etc/yum.repos.d/kubernetes.repo"，内容如下：

[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

添加完成后，安装kubelet,kubeadm,kubectl：

1. master node

[root@master ~]# yum install kubelet kubeadm kubectl -y

2. client node

[root@client ~]# yum install kubelet kubeadm kubectl -y

2.2.2 配置kubelet

kubernetes自1.8版本其强制要求关闭系统上的交换分区，否则无法启动，由于我们的虚机内存资源有限，需要保留交换分区，所以我们修改kubernetes的参数用以忽略禁止使用交换分区的限制，分别在master node 和 client node上修改文件"/etc/sysconfig/kubelet"参数如下：

KUBELET_EXTRA_ARGS="--fail-swap-on=false"

修改完成后，设置kubelet服务开机自启动。

1. master node

[root@master ~]# systemctl enable kubelet
Created symlink from /etc/systemd/system/multi-user.target.wants/kubelet.service to /usr/lib/systemd/system/kubelet.service.

2. client node

[root@client ~]# systemctl enable kubelet
Created symlink from /etc/systemd/system/multi-user.target.wants/kubelet.service to /usr/lib/systemd/system/kubelet.service.

2.2.3 下载docker image

正常流程，我们应该直接进行2.2.4集群初始化，但是由于墙的原因，我们在2.2.4集群初始化之前就需要先手动下载docker image。

首先在master node上查看集群初始化所需docker image版本：

1. master node

[root@master ~]# kubeadm config images list
k8s.gcr.io/kube-apiserver:v1.17.4
k8s.gcr.io/kube-controller-manager:v1.17.4
k8s.gcr.io/kube-scheduler:v1.17.4
k8s.gcr.io/kube-proxy:v1.17.4
k8s.gcr.io/pause:3.1
k8s.gcr.io/etcd:3.4.3-0
k8s.gcr.io/coredns:1.6.5

然后我们将"k8s.gcr.io"替换为国内阿里的镜像源如下"registry.cn-hangzhou.aliyuncs.com/google_containers"，然后在master node上输入以下命令手动下载：

1. master node

[root@master ~]# docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-apiserver:v1.17.4
[root@master ~]# docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-controller-manager:v1.17.4
[root@master ~]# docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-scheduler:v1.17.4
[root@master ~]# docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-proxy:v1.17.4
[root@master ~]# docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.1
[root@master ~]# docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.4.3-0
[root@master ~]# docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:1.6.5

下载完成后，更改image tag，通过修改image tag将我们从阿里镜像源下载的docker image修改回原有的"k8s.gcr.io"以供kubeadm初始化使用，其中docker tag后的第一个参数是我们从阿里镜像源下载的镜像名字，第二个参数是我们使用"kubeadm config images list"查看到的镜像名字：

1. master node

[root@master ~]# docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-apiserver:v1.17.4 k8s.gcr.io/kube-apiserver:v1.17.4
[root@master ~]# docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-controller-manager:v1.17.4 k8s.gcr.io/kube-controller-manager:v1.17.4
[root@master ~]# docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-scheduler:v1.17.4 k8s.gcr.io/kube-scheduler:v1.17.4
[root@master ~]# docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-proxy:v1.17.4 k8s.gcr.io/kube-proxy:v1.17.4
[root@master ~]# docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.1 k8s.gcr.io/pause:3.1
[root@master ~]# docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.4.3-0 k8s.gcr.io/etcd:3.4.3-0
[root@master ~]# docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:1.6.5 k8s.gcr.io/coredns:1.6.5

2.2.4 集群初始化

在master node上运行以下命令：

1. master node

[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=0.0.0.0 --ignore-preflight-errors=Swap

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Note:

1. –kubernetes-version：要替换成你的kubernets版本，可使用"kubectl version"命令查看。
2. –pod-network-cidr：Pod网络的地址范围，我们后续使用flannel网络插件，其默认地址为 10.244.0.0/16。
3. –service-cidr：默认地址是10.96.0.0/12。
4. –apiserver-advertise-address： API server通告给其他组件的IP地址，一般应该为master node的IP地址，0.0.0.0表示节点上所有可用的地址。
5. –ignore-preflight-errors：忽略运行时错误信息，因为我们没有关闭swap，kubernets需要禁用swap，所以我们在这里忽略swap导致的失败。

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如果运行中报错"/proc/sys/net/bridge/bridge-nf-call-iptables contents are not set to 1"，在master node和client node分别运行：

1. master node

[root@master ~]# echo 1 > /proc/sys/net/bridge/bridge-nf-call-iptables

2. client node

[root@client ~]# echo 1 > /proc/sys/net/bridge/bridge-nf-call-iptables

如果一切顺利，运行完"kubeadm init"命令后master node得到以下输出：

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 192.168.1.10:6443 --token z66onn.645t3tg2rdpa0iib \
    --discovery-token-ca-cert-hash sha256:b201b3343a2253b4eafb529a79fccc8d70a4c7a440041167eda045c378284f13

2.2.5 设置kubectl配置文件

设置配置文件：

1. master node

[root@master ~]# mkdir -p $HOME/.kube
[root@master ~]# cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

查看集群组件状态：

1. master node

[root@master ~]# kubectl get cs
NAME                 STATUS    MESSAGE             ERROR
scheduler            Healthy   ok                  
controller-manager   Healthy   ok                  
etcd-0               Healthy   {"health":"true"}

如果status都为healthy，那么说明2.2.4集群初始化运行成功，否则需要重新初始化。

查看node状态：

1. master node

[root@master ~]# kubectl get node
NAME     STATUS     ROLES    AGE     VERSION
master   NotReady   master   9m25s   v1.17.4

显示node状态为notready，不要紧张，这是正常的，因为我们还没有安装网络插件，安装后就会是ready状态。

2.2.6 安装网络插件

下载flannel配置清单，下载地址：https://github.com/coreos/flannel/blob/master/Documentation/kube-flannel.yml

然后再master node上新建flannel_config.yaml的文件，将配置清单内容复制进文件。

master node运行命令：

[root@master ~]# kubectl apply -f flannel_config.yaml
podsecuritypolicy.policy/psp.flannel.unprivileged created
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.apps/kube-flannel-ds-amd64 created
daemonset.apps/kube-flannel-ds-arm64 created
daemonset.apps/kube-flannel-ds-arm created
daemonset.apps/kube-flannel-ds-ppc64le created
daemonset.apps/kube-flannel-ds-s390x created

运行完成后，在master node上检查flannel pod的状态，直到状态为Running时，表示flannel已安装完成。

1. master node

[root@master ~]# kubectl get pods -A
NAMESPACE     NAME                             READY   STATUS    RESTARTS   AGE
kube-system   coredns-6955765f44-2cc4z         1/1     Running   0          13h
kube-system   coredns-6955765f44-f4b55         1/1     Running   0          13h
kube-system   etcd-master                      1/1     Running   1          13h
kube-system   kube-apiserver-master            1/1     Running   1          13h
kube-system   kube-controller-manager-master   1/1     Running   1          13h
kube-system   kube-flannel-ds-amd64-pbdg9      1/1     Running   0          5m22s
kube-system   kube-proxy-vk8tr                 1/1     Running   1          13h
kube-system   kube-scheduler-master            1/1     Running   1          13h

查看node状态，已经变为Ready

1. master node

[root@master ~]# kubectl get node
NAME     STATUS   ROLES    AGE   VERSION
master   Ready    master   13h   v1.17.4

2.2.7 client node加入集群

我们在client node上输入2.2.4 集群初始化中kubeadm init输出中的

kubeadm join 192.168.1.10:6443 --token z66onn.645t3tg2rdpa0iib --discovery-token-ca-cert-hash sha256:b201b3343a2253b4eafb529a79fccc8d70a4c7a440041167eda045c378284f13

同时，加上"–ignore-preflight-errors=Swap"

1. client node

[root@client ~]# kubeadm join 192.168.1.10:6443 --token z66onn.645t3tg2rdpa0iib --discovery-token-ca-cert-hash sha256:b201b3343a2253b4eafb529a79fccc8d70a4c7a440041167eda045c378284f13 --ignore-preflight-errors=Swap

运行完后，查看，在client node上查看显示：

1. client node

[root@client ~]# kubectl get nodes
W0323 04:13:48.193623    4259 loader.go:223] Config not found: /etc/kubernetes/admin.conf
The connection to the server localhost:8080 was refused - did you specify the right host or port?

解决方法，在master node上运行：

1. master node

[root@master ~]# scp /etc/kubernetes/admin.conf root@client:/etc/kubernetes/

然后在client node上运行：

1. client node

[root@client ~]# echo "export KUBECONFIG=/etc/kubernetes/admin.conf" >> ~/.bash_profile
[root@client ~]# source .bashrc_profile

然后再次在client node上查看node和pod状态：

1. client node

[root@client ~]# kubectl get nodes
NAME     STATUS     ROLES    AGE   VERSION
client   NotReady      34s   v1.17.4
master   Ready      master   18h   v1.17.4
[root@client ~]# kubectl get pods -n kube-system
NAME                             READY   STATUS              RESTARTS   AGE
coredns-6955765f44-2cc4z         1/1     Running             0          18h
coredns-6955765f44-f4b55         1/1     Running             0          18h
etcd-master                      1/1     Running             1          18h
kube-apiserver-master            1/1     Running             1          18h
kube-controller-manager-master   1/1     Running             1          18h
kube-flannel-ds-amd64-pbdg9      1/1     Running             0          5h50m
kube-flannel-ds-amd64-pvhbr      0/1     Init:0/1            0          5m40s
kube-proxy-dgk4b                 0/1     ContainerCreating   0          5m40s
kube-proxy-vk8tr                 1/1     Running             1          18h
kube-scheduler-master            1/1     Running             1          18h

node一直是notready，pod也起不来，查看log显示：

1. master node

[root@master ~]# kubectl describe pod kube-proxy-dzz66 -n kube-system
Name:                 kube-proxy-dzz66
Namespace:            kube-system
Priority:             2000001000
Priority Class Name:  system-node-critical
Node:                 client/192.168.1.11
Start Time:           Mon, 23 Mar 2020 10:29:08 -0400
Labels:               controller-revision-hash=949fbc8
                      k8s-app=kube-proxy
                      pod-template-generation=1
Annotations:          
Status:               Pending
IP:                   192.168.1.11
IPs:
  IP:           192.168.1.11
Controlled By:  DaemonSet/kube-proxy
Containers:
  kube-proxy:
    Container ID:  
    Image:         k8s.gcr.io/kube-proxy:v1.17.4
    Image ID:      
    Port:          
    Host Port:     
    Command:
      /usr/local/bin/kube-proxy
      --config=/var/lib/kube-proxy/config.conf
      --hostname-override=$(NODE_NAME)
    State:          Waiting
      Reason:       ContainerCreating
    Ready:          False
    Restart Count:  0
    Environment:
      NODE_NAME:   (v1:spec.nodeName)
    Mounts:
      /lib/modules from lib-modules (ro)
      /run/xtables.lock from xtables-lock (rw)
      /var/lib/kube-proxy from kube-proxy (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from kube-proxy-token-cnrll (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             False 
  ContainersReady   False 
  PodScheduled      True 
Volumes:
  kube-proxy:
    Type:      ConfigMap (a volume populated by a ConfigMap)
    Name:      kube-proxy
    Optional:  false
  xtables-lock:
    Type:          HostPath (bare host directory volume)
    Path:          /run/xtables.lock
    HostPathType:  FileOrCreate
  lib-modules:
    Type:          HostPath (bare host directory volume)
    Path:          /lib/modules
    HostPathType:  
  kube-proxy-token-cnrll:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  kube-proxy-token-cnrll
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  beta.kubernetes.io/os=linux
Tolerations:     
                 CriticalAddonsOnly
                 node.kubernetes.io/disk-pressure:NoSchedule
                 node.kubernetes.io/memory-pressure:NoSchedule
                 node.kubernetes.io/network-unavailable:NoSchedule
                 node.kubernetes.io/not-ready:NoExecute
                 node.kubernetes.io/pid-pressure:NoSchedule
                 node.kubernetes.io/unreachable:NoExecute
                 node.kubernetes.io/unschedulable:NoSchedule
Events:
  Type     Reason                  Age                 From               Message
  ----     ------                  ----                ----               -------
  Normal   Scheduled               4m40s               default-scheduler  Successfully assigned kube-system/kube-proxy-dzz66 to client
  Warning  FailedCreatePodSandBox  47s (x5 over 4m4s)  kubelet, client    Failed to create pod sandbox: rpc error: code = Unknown desc = failed pulling image "k8s.gcr.io/pause:3.1": Error response from daemon: Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)

显示client node上pull docker image不成功，所以干脆又把之前在master node上下载docker image，更改image tag的命令在client node上重新运行一次，步骤参考2.2.3。

再次在client node上查看pod，node状态:

1. client node

[root@client ~]# kubectl get pods -n kube-system
NAME                             READY   STATUS    RESTARTS   AGE
coredns-6955765f44-kzzdq         1/1     Running   0          25m
coredns-6955765f44-zd76j         1/1     Running   0          25m
etcd-master                      1/1     Running   0          25m
kube-apiserver-master            1/1     Running   0          25m
kube-controller-manager-master   1/1     Running   0          25m
kube-flannel-ds-amd64-49h6h      1/1     Running   0          21m
kube-flannel-ds-amd64-g6tr7      1/1     Running   0          21m
kube-proxy-c42pz                 1/1     Running   0          25m
kube-proxy-dzz66                 1/1     Running   0          24m
kube-scheduler-master            1/1     Running   0          25m
[root@client ~]# kubectl get nodes
NAME     STATUS   ROLES    AGE   VERSION
client   Ready       24m   v1.17.4
master   Ready    master   25m   v1.17.4

至此，成功。

Note:
如果安装flannel插件过程中，image下载有问题，可以使用以下repo下载并更改tag：

docker pull quay-mirror.qiniu.com/coreos/flannel:v0.12.0-amd64
docker tag quay-mirror.qiniu.com/coreos/flannel:v0.12.0-amd64 quay.io/coreos/flannel:v0.12.0-amd64

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