本文主要是介绍CentOS 7安装指定版本kubernetes，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

我们知道kubernetes.io有文档指导我们如何安装kubernetes，例如kubeadm，按照此方法默认安装最新版本的kubernetes，例如当前（2021-05-11）为v1.21.0

如果是学生党搞搞学习或者研究党搞搞研究，那自然是最新的稳定版本最好了，但是作为参加工作的研发人员，事情往往就没那么简单了，产品使用的版本一般都落后于开源版本，半年甚至更久，所以产品研发人员一般需要部署指定版本的kubernetes用于验证某些功能，这就是本文要讲述的内容

安装kubeadm、kubelet和kubectl

参照kubeadm，当执行到“安装kubeadm、kubelet和kubectl”这一步时，会创建一个repo文件：/etc/yum.repos.d/kubernetes.repo，然后执行：yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes安装最新的稳定版本，我们应该在这里区分开来，具体操作如下：

1. 从进入到“安装kubeadm、kubelet和kubectl”这一步开始
2. 从repo文件内容中可以找到baseurl=xxx，我们打开repos，ctrl+F搜索kubernetes，找到对应的架构，例如我是aarch64，就选择kubernetes-el7-aarch64
3. 点击进入后有两个链接，点击repodata，然后点击primary.xml
4. 从primary.xml中找到需要的版本，例如我需要的是1.16.0：
   1. kubectl：http://yum.kubernetes.io/pool/b89f9c89cf0163bfd4f3d1e3a747856fa77b0c8b0bdec747acab95789103560a-kubectl-1.16.0-0.aarch64.rpm
   2. kubelet：http://yum.kubernetes.io/pool/392b7313850b2cf63cd68d7a5ee6505d9d9e05c7e398d41c93b1e60bc9214310-kubelet-1.16.0-0.aarch64.rpm
   3. kubeadm：http://yum.kubernetes.io/pool/227fa407cae2ba5e79b3643f007bce0f7982a5c02a22ab2480e921304c85b355-kubeadm-1.16.0-0.aarch64.rpm
5. yum安装找到的rpm

   yum install -y http://yum.kubernetes.io/pool/b89f9c89cf0163bfd4f3d1e3a747856fa77b0c8b0bdec747acab95789103560a-kubectl-1.16.0-0.aarch64.rpm
   yum install -y http://yum.kubernetes.io/pool/392b7313850b2cf63cd68d7a5ee6505d9d9e05c7e398d41c93b1e60bc9214310-kubelet-1.16.0-0.aarch64.rpm
   yum install -y http://yum.kubernetes.io/pool/227fa407cae2ba5e79b3643f007bce0f7982a5c02a22ab2480e921304c85b355-kubeadm-1.16.0-0.aarch64.rpm

    

6. kubeadm version确认安装情况

   [root@ecs-57f4 ~]# kubeadm version
   kubeadm version: &version.Info{Major:"1", Minor:"16", GitVersion:"v1.16.0", GitCommit:"2bd9643cee5b3b3a5ecbd3af49d09018f0773c77", GitTreeState:"clean", BuildDate:"2019-09-18T14:34:01Z", GoVersion:"go1.12.9", Compiler:"gc", Platform:"linux/arm64"}

    

注意：除了安装kubeadm、kubectl、kubelet外，其他步骤按照指导文档执行

使用kubeadm安装kubernetes集群

需要注意的是，通过--kubernetes-version指定kubernetes的版本，具体命令如下

kubeadm init --kubernetes-version 1.16.0 --pod-network-cidr 10.0.0.0/16

我使用的是crio v1.21.0作为容器运行时，遇到了kubelet跟crio的cgroup driver不匹配的问题，具体解决的办法是：systemctl status kubelet 可以看到Drop-In: /usr/lib/systemd/system/kubelet.service.d 下面kubeadm添加了一个配置文件：10-kubeadm.conf，修改改文件，增加KUBELET_CGROUP_ARGS（注意：需要改两行，一是新增Environment，二是ExecStart后面添加该参数）：

# Note: This dropin only works with kubeadm and kubelet v1.11+
[Service]
Environment="KUBELET_CGROUP_ARGS=--cgroup-driver=systemd"
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"
Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"
# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/sysconfig/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS $KUBELET_CGROUP_ARGS

等待kubeadm安装完成即可

[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
[kubelet-check] Initial timeout of 40s passed.
[apiclient] All control plane components are healthy after 213.501765 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.16" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node ecs-57f4 as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node ecs-57f4 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: 7524n3.ctfh768j7xi6d4qy
[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 192.168.0.45:6443 --token 7524n3.ctfh768j7xi6d4qy \
    --discovery-token-ca-cert-hash sha256:8c244d0a30da0d0d950609ee8fddff5f28b1bd76de21ecfe682923830450655d 
[root@ecs-57f4 ~]#

此时我们执行：kubectl get node会发现node状态为NotReady，不要慌，安装一下网络插件即可

安装网络插件

我选择的是flannel，按照指定kubernetes 1.17+可以一条命令搞定，但我安装的是1.16.0，所以点击链接继续研究，发现：

For Kubernetes v1.16

kube-flannel.yaml uses ClusterRole & ClusterRoleBinding of rbac.authorization.k8s.io/v1. When you use Kubernetes v1.16, you should replace rbac.authorization.k8s.io/v1 to rbac.authorization.k8s.io/v1beta1 because rbac.authorization.k8s.io/v1 had become GA from Kubernetes v1.17.

所以安装脚本修改为：

wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
sed -i 's#rbac.authorization.k8s.io/v1#rbac.authorization.k8s.io/v1beta1#g' kube-flannel.yml
kubectl apply -f kube-flannel.yml

然后执行命令：kubectl get po -A 等待所以pod编程Running即可

验证

[root@ecs-57f4 ~]# kubectl get node -owide
NAME       STATUS   ROLES    AGE   VERSION   INTERNAL-IP    EXTERNAL-IP   OS-IMAGE                   KERNEL-VERSION              CONTAINER-RUNTIME
ecs-57f4   Ready    master   62m   v1.16.0   192.168.0.45   <none>        CentOS Linux 7 (AltArch)   4.18.0-80.7.2.el7.aarch64   cri-o://1.21.0
[root@ecs-57f4 ~]# 
[root@ecs-57f4 ~]# 
[root@ecs-57f4 ~]# kubectl version
Client Version: version.Info{Major:"1", Minor:"16", GitVersion:"v1.16.0", GitCommit:"2bd9643cee5b3b3a5ecbd3af49d09018f0773c77", GitTreeState:"clean", BuildDate:"2019-09-18T14:36:53Z", GoVersion:"go1.12.9", Compiler:"gc", Platform:"linux/arm64"}
Server Version: version.Info{Major:"1", Minor:"16", GitVersion:"v1.16.0", GitCommit:"2bd9643cee5b3b3a5ecbd3af49d09018f0773c77", GitTreeState:"clean", BuildDate:"2019-09-18T14:27:17Z", GoVersion:"go1.12.9", Compiler:"gc", Platform:"linux/arm64"}
[root@ecs-57f4 ~]# kubectl get node -owide
NAME       STATUS   ROLES    AGE   VERSION   INTERNAL-IP    EXTERNAL-IP   OS-IMAGE                   KERNEL-VERSION              CONTAINER-RUNTIME
ecs-57f4   Ready    master   62m   v1.16.0   192.168.0.45   <none>        CentOS Linux 7 (AltArch)   4.18.0-80.7.2.el7.aarch64   cri-o://1.21.0
[root@ecs-57f4 ~]# kubectl get po -A
NAMESPACE     NAME                               READY   STATUS        RESTARTS   AGE
kube-system   coredns-5644d7b6d9-5jqvz           1/1     Running       0          66m
kube-system   coredns-5644d7b6d9-zzn9c           1/1     Running       0          66m
kube-system   etcd-ecs-57f4                      1/1     Running       0          65m
kube-system   kube-apiserver-ecs-57f4            1/1     Running       0          65m
kube-system   kube-controller-manager-ecs-57f4   1/1     Running       0          65m
kube-system   kube-flannel-ds-7vk9n              1/1     Running       0          62m
kube-system   kube-proxy-c5m8c                   1/1     Running       0          66m
kube-system   kube-scheduler-ecs-57f4            1/1     Running       0          65m

我们再部署一个应用做简单的测试

[root@ecs-57f4 ~]# cat nginx-deployment.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1 # tells deployment to run 2 pods matching the template
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: docker.io/library/nginx:1.14.2
        ports:
        - containerPort: 80
[root@ecs-57f4 ~]# kubectl apply -f nginx-deployment.yaml 
deployment.apps/nginx created
[root@ecs-57f4 ~]# kubectl get po 
NAME                    READY   STATUS    RESTARTS   AGE
nginx-685d968c9-xzl6f   1/1     Running   0          5s
[root@ecs-57f4 ~]# kubectl exec -it nginx-685d968c9-xzl6f -- ls -lh
total 64K
drwxr-xr-x   1 root root 4.0K Mar 27  2019 bin
drwxr-xr-x   2 root root 4.0K Feb  3  2019 boot
drwxr-xr-x   5 root root  360 May 11 09:13 dev
drwxr-xr-x   1 root root 4.0K May 11 09:13 etc
drwxr-xr-x   2 root root 4.0K Feb  3  2019 home
drwxr-xr-x   1 root root 4.0K Mar 27  2019 lib
drwxr-xr-x   2 root root 4.0K Mar 26  2019 media
drwxr-xr-x   2 root root 4.0K Mar 26  2019 mnt
drwxr-xr-x   2 root root 4.0K Mar 26  2019 opt
dr-xr-xr-x 185 root root    0 May 11 09:13 proc
drwx------   2 root root 4.0K Mar 26  2019 root
drwxr-xr-x   1 root root 4.0K May 11 09:13 run
drwxr-xr-x   2 root root 4.0K Mar 26  2019 sbin
drwxr-xr-x   2 root root 4.0K Mar 26  2019 srv
dr-xr-xr-x  12 root root    0 May 11 09:13 sys
drwxrwxrwt   1 root root 4.0K Mar 27  2019 tmp
drwxr-xr-x   1 root root 4.0K Mar 26  2019 usr
drwxr-xr-x   1 root root 4.0K Mar 26  2019 var
[root@ecs-57f4 ~]#

参考链接

• 安装 kubeadm

• 使用 kubeadm 创建集群

• flannel

• 繼上篇，排查 kubelet、kubeadm init 問題

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