Kubernetes指南: 从零开始搭建集群

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在云计算时代，容器化已经成为了一种广泛使用的技术，Kubernetes是其中的佼佼者，其作为一个容器编排平台，在管理上的优势及其高可用性、易扩展性深受企业和开发者的喜爱。在本文章中，我们将从零开始搭建Kubernetes集群，并解释其中的技术知识点。

1. 环境准备

在开始之前，需要先确定好环境，Kubernetes分为Master节点和Worker节点，其中Master节点需要至少2个，Worker节点至少1个，硬件环境和软件环境需要满足一定的要求。硬件环境建议：

- Master节点：CPU 2核，内存 2GB，硬盘 40GB以上

- Worker节点：CPU 4核，内存 4GB，硬盘 40GB以上

软件环境建议：

- 操作系统：CentOS7.4以上

- Docker：18.09.0以上

- Kubeadm：1.20.1及以上

2. 安装Docker

在CentOS系统下，我们可以执行下方脚本安装Docker：

`bash

$ sudo yum install -y yum-utils device-mapper-persistent-data lvm2

$ sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

$ sudo yum install -y docker-ce-18.09.0 docker-ce-cli-18.09.0 containerd.io

$ sudo systemctl start docker

$ sudo systemctl enable docker

3. 安装Kubeadm我们可以执行如下脚本安装Kubeadm：`bash$ sudo vi /etc/sysctl.d/k8s.conf # 写入如下内容net.bridge.bridge-nf-call-ip6tables = 1net.bridge.bridge-nf-call-iptables = 1$ sudo sysctl --system$ sudo setenforce 0$ sudo sed -i 's/SELINUX=enforcing/SELINUX=permissive/' /etc/selinux/config $ sudo vi /etc/yum.repos.d/kubernetes.repo# 写入如下内容[kubernetes]name=Kubernetesbaseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/enabled=1gpgcheck=0repo_gpgcheck=0gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg$ sudo yum install -y kubelet-1.20.1 kubeadm-1.20.1 kubectl-1.20.1 --disableexcludes=kubernetes$ sudo systemctl enable kubelet$ sudo systemctl start kubelet

4. 搭建Master节点

在搭建Master节点时，我们需要先确定好IP地址，并编辑好如下配置文件：

`yaml

apiVersion: kubeadm.k8s.io/v1beta2

kind: ClusterConfiguration

kubernetesVersion: stable

apiServer:

certSANs:

- "{{ Master节点IP地址 }}"

controlPlaneEndpoint: "{{ Master节点IP地址 }}:6443"

extraArgs:

audit-log-path: /var/log/kubernetes/audit.log

audit-log-maxage: "30"

audit-log-maxbackup: "3"

audit-log-maxsize: "100"

authorization-mode: Node,RBAC

enable-admission-plugins: NamespaceLifecycle,LimitRanger,ServiceAccount,DefaultStorageClass,ResourceQuota

runtime-config: api/all=true

service-node-port-range: 30000-32767

controllerManager:

extraArgs:

node-cidr-mask-size: "24"

node-monitor-grace-period: "30s"

pod-eviction-timeout: "2m"

use-service-account-credentials: "true"

networking:

dnsDomain: cluster.local

podSubnet: "10.244.0.0/16"

serviceSubnet: "10.96.0.0/12"

然后，我们在Master节点上执行如下脚本：`bash$ sudo kubeadm init --config kubeadm-config.yaml

在执行完成后，我们可以看到如下输出：

`bash

[init] Using Kubernetes version: v1.20.0

[preflight] Running pre-flight checks

[WARNING FileExisting-crictl]: crictl not found in system path

[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] Starting the kubelet

[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-1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.1.120]

[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 [localhost] and IPs [192.168.1.120 127.0.0.1 ::1]

[certs] Generating "etcd/peer" certificate and key

[certs] etcd/peer serving cert is signed for DNS names [localhost] and IPs [192.168.1.120 127.0.0.1 ::1]

[certs] Generating "etcd/healthcheck-client" certificate and key

[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

[kubelet-check] Initial timeout of 40s passed.

[apiclient] All control plane components are healthy after 80.001069 seconds

[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace

[kubelet] Creating a ConfigMap "kubelet-config-1.20" in namespace kube-system with the configuration for the kubelets in the cluster

[kubelet-start] Restarting the kubelet to use the new kubelet configuration

[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

[csr-approver] CSR approval is disabled. Nodes that match this CSR will be not be permitted to join the cluster. Passing --apiserver-advertise-address=0.0.0.0 may allow unauthorized nodes to join the cluster.

[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster

[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

Alternatively, if you are the root user, you can run:

export KUBECONFIG=/etc/kubernetes/admin.conf

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 {{ Master节点IP地址 }}:6443 --token {{ Token }} \

--discovery-token-ca-cert-hash sha256:{{ CA证书哈希值 }}

在执行完成后，我们需要执行如下脚本，让普通用户也拥有使用Kubernetes的权限：`bash$ mkdir -p $HOME/.kube$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config$ sudo chown $(id -u):$(id -g) $HOME/.kube/config

5. 搭建Worker节点

在搭建Worker节点时，我们需要使用之前Master节点输出的join命令，并将其执行在Worker节点上，如下：

`bash

$ sudo kubeadm join {{ Master节点IP地址 }}:6443 --token {{ Token }} \

--discovery-token-ca-cert-hash sha256:{{ CA证书哈希值 }}

执行成功后，在Master节点上执行如下脚本：`bash$ kubectl get nodes

如果输出了刚刚加入的Worker节点信息，说明Worker节点已经成功加入到了集群中。

至此，我们已经成功搭建了一个Kubernetes集群，并且已经加入了一个Worker节点。在实际生产环境中，我们还需要进行更多的配置和优化，例如网络、存储、高可用性等方面，这将在后续的文章中进行探讨。

本文名称：Kubernetes指南从零开始搭建集群
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