我们想在CentOS 7/CentOS 8上为开发项目设置一个三节点Kubernetes集群-1个主节点和两个或者多个Worker节点？
本教程将引导我们完成在运行并配置了防火墙的Ansible和Calico CNI的CentOS 8/CentOS 7 Linux机器上设置Kubernetes群集的步骤。
Kubernetes(K8s)是一个开源系统，用于自动化容器化应用程序的部署，扩展和管理。

类似的Kubernetes部署教程：使用Rancher RKE安装Production Kubernetes集群如何使用K3s在5分钟内部署轻量级Kubernetes集群使用Ansible&Kubespray部署可用于生产的Kubernetes集群

我的实验室基于以下环境：

首先，请确保系统已更新，并安装所有依赖项，包括容器运行时，Kubernetes软件包以及为k8s配置防火墙。

步骤1：设定标准要求

我写了一个Ansible角色来进行标准的Kubernetes节点准备工作。
该角色包含以下任务：安装必需的基本软件包设置标准系统要求–禁用交换，修改sysctl，禁用SELinux安装和配置我们选择的容器运行时– cri-o，Docker，Containerd安装Kubernetes软件包– kubelet，kubeadm和kubectl Kubernetes主节点和工作节点访问我的Github页面进行设置：https：//github.com/jmutai/k8s-pre-bootstrap这是我最近执行的输出：

TASK [kubernetes-bootstrap : Open flannel ports on the firewall] ** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** *****
skipping: [k8smaster01] => (item=8285) 
skipping: [k8smaster01] => (item=8472) 
skipping: [k8snode01] => (item=8285) 
skipping: [k8snode01] => (item=8472) 
skipping: [k8snode02] => (item=8285) 
skipping: [k8snode02] => (item=8472) 
TASK [kubernetes-bootstrap : Open calico UDP ports on the firewall] ** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **
ok: [k8snode01] => (item=4789)
ok: [k8smaster01] => (item=4789)
ok: [k8snode02] => (item=4789)
TASK [kubernetes-bootstrap : Open calico TCP ports on the firewall] ** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **
ok: [k8snode02] => (item=5473)
ok: [k8snode01] => (item=5473)
ok: [k8smaster01] => (item=5473)
ok: [k8snode01] => (item=179)
ok: [k8snode02] => (item=179)
ok: [k8smaster01] => (item=179)
ok: [k8snode02] => (item=5473)
ok: [k8snode01] => (item=5473)
ok: [k8smaster01] => (item=5473)
TASK [kubernetes-bootstrap : Reload firewalld] ** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** ***
changed: [k8smaster01]
changed: [k8snode01]
changed: [k8snode02]
PLAY RECAP ** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** ***
k8smaster01                : ok=23   changed=3    unreachable=0    failed=0    skipped=11   rescued=0    ignored=0   
k8snode01                  : ok=23   changed=3    unreachable=0    failed=0    skipped=11   rescued=0    ignored=0   
k8snode02                  : ok=23   changed=3    unreachable=0    failed=0    skipped=11   rescued=0    ignored=0

步骤2：初始化单节点控制平面

此部署适用于具有集成etcd的单个控制平面节点。
如果我们要执行多个控制节点(HA时为3个)，请查看使用kubeadm创建高可用性集群的官方教程。
我们将使用kubeadm引导符合最佳实践的最小可行Kubernetes集群。
kubeadm的好处是它支持其他集群生命周期功能，例如升级，降级和管理引导令牌。
单个控制节点引导要求：控制节点机器的默认IP地址DNS域名/负载均衡器IP(如果我们打算添加更多)稍后控制节点以root用户或者使用sudoLogin的用户的SSH访问控制节点：

$ssh Hyman@theitroad

检查可用于初始化Kubernetes集群的参数：

$kubeadm init --help

我们将使用的标准参数为： --pod-network-cidr：用于指定Pod网络的IP地址范围。 --apiserver-advertise-address：API服务器将宣告其正在监听的IP地址。 --control-plane-endpoint：为控制平面指定一个稳定的IP地址或者DNS名称。 --upload-certs：将控制平面证书上传到kubeadm-certs Secret。
如果使用Calico，建议的Pod网络为：192.168.0.0/16对于Flannel，建议将Pod网络设置为10.244.0.0/16对于我来说，我将运行命令：

sudo kubeadm init \
  --apiserver-advertise-address=192.168.122.10 \
  --pod-network-cidr 192.168.0.0/16 \
  --upload-certs

为了能够将单个控制平面kubeadm集群升级到高可用性，我们应该指定–-control-plane-endpoint来设置所有控制平面节点的共享端点。
这样的端点可以是负载均衡器的DNS名称或者IP地址。

kubeadm init \
  --apiserver-advertise-address=192.168.122.227 \
  --pod-network-cidr 192.168.0.0/16 \
  --control-plane-endpoint <DNS-End-Point>
  --upload-certs

这是我的安装输出：

W0109 20:27:51.787966   18069 validation.go:28] Cannot validate kube-proxy config - no validator is available
W0109 20:27:51.788126   18069 validation.go:28] Cannot validate kubelet config - no validator is available
[init] Using Kubernetes version: v1.17.0
[preflight] Running pre-flight checks
	[WARNING Firewalld]: firewalld is active, please ensure ports [6443 10250] are open or your cluster Jan not function correctly
[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 [k8smaster01.theitroad.com kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.122.10]
[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 [k8smaster01.theitroad.com localhost] and IPs [192.168.122.10 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8smaster01.theitroad.com localhost] and IPs [192.168.122.10 127.0.0.1 ::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"
W0109 20:32:51.776569   18069 manifests.go:214] the default kube-apiserver authorization-mode is "Node,RBAC"; using "Node,RBAC"
[control-plane] Creating static Pod manifest for "kube-scheduler"
W0109 20:32:51.777334   18069 manifests.go:214] the default kube-apiserver authorization-mode is "Node,RBAC"; using "Node,RBAC"
[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 15.507327 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.17" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Storing the certificates in Secret "kubeadm-certs" in the "kube-system" Namespace
[upload-certs] Using certificate key:
bce5c1ad320f4c64e42688e25526615d2ffd7efad3e749bc0c632b3a7834752d
[mark-control-plane] Marking the node k8smaster01.theitroad.com as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node k8smaster01.theitroad.com as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: nx1jjq.u42y27ip3bhmj8vj
[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
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[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 192.168.122.10:6443 --token nx1jjq.u42y27ip3bhmj8vj \
    --discovery-token-ca-cert-hash sha256:c6de85f6c862c0d58cc3d10fd199064ff25c4021b6e88475822d6163a25b4a6c

复制kubectl配置文件。

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

还请结帐：使用kubectl和kubectx轻松管理多个Kubernetes集群

将Pod网络部署到集群

我将使用Calico，但我们可以自由使用我们选择的任何其他Pod Network插件。

kubectl apply -f https://docs.projectcalico.org/v3.8/manifests/calico.yaml

如下面的输出所示，这将创建许多资源。

configmap/calico-config created
customresourcedefinition.apiextensions.k8s.io/felixconfigurations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipamblocks.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/blockaffinities.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipamhandles.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipamconfigs.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/bgppeers.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/bgpconfigurations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ippools.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/hostendpoints.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/clusterinformations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/globalnetworkpolicies.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/globalnetworksets.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/networkpolicies.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/networksets.crd.projectcalico.org created
clusterrole.rbac.authorization.k8s.io/calico-kube-controllers created
clusterrolebinding.rbac.authorization.k8s.io/calico-kube-controllers created
clusterrole.rbac.authorization.k8s.io/calico-node created
clusterrolebinding.rbac.authorization.k8s.io/calico-node created
daemonset.apps/calico-node created
serviceaccount/calico-node created
deployment.apps/calico-kube-controllers created
serviceaccount/calico-kube-controllers created

使用以下命令确认所有Pod都在运行。

watch kubectl get pods --all-namespaces

一旦一切运行正常，输出将如下所示。

NAMESPACE     NAME                                                        READY   STATUS    RESTARTS   AGE
kube-system   calico-kube-controllers-5c45f5bd9f-c8mwx                    1/1     Running   0          3m45s
kube-system   calico-node-m5qmb                                           1/1     Running   0          3m45s
kube-system   coredns-6955765f44-cz65r                                    1/1     Running   0          9m43s
kube-system   coredns-6955765f44-mtch2                                    1/1     Running   0          9m43s
kube-system   etcd-k8smaster01.theitroad.com                      1/1     Running   0          9m59s
kube-system   kube-apiserver-k8smaster01.theitroad.com            1/1     Running   0          9m59s
kube-system   kube-controller-manager-k8smaster01.theitroad.com   1/1     Running   0          9m59s
kube-system   kube-proxy-bw494                                            1/1     Running   0          9m43s
kube-system   kube-scheduler-k8smaster01.theitroad.com            1/1     Running   0          9m59s

请注意，每个Pod都有 STATUS的 Running请查看Calico文档以获取更多详细信息。

步骤3：将工作节点加入集群

现在，我们已经准备好控制节点，可以添加将其中运行工作负载(容器和Pod等)的新节点。
我们需要在每台用于运行Pods.SSH的计算机上执行此操作

$ssh Hyman@theitroad

运行kubeadm init输出的命令。
例如：

sudo kubeadm join 192.168.122.10:6443 --token nx1jjq.u42y27ip3bhmj8vj \
    --discovery-token-ca-cert-hash sha256:c6de85f6c862c0d58cc3d10fd199064ff25c4021b6e88475822d6163a25b4a6c

如果令牌已过期，则可以使用以下命令生成一个新令牌：

kubeadm token create

获取令牌

kubeadm token list

我们可以使用以下命令获取Discovery-token-ca-cert-hash的值：

openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //'

这是一个连接命令输出：

[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.17" ConfigMap in the kube-system namespace
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...
This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.
Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

在所有其他Worker节点上运行相同的join命令，然后查看使用以下命令加入集群的可用节点：

$kubectl get nodes
NAME                                STATUS   ROLES    AGE     VERSION
k8smaster01.theitroad.com   Ready    master   26m     v1.17.0
k8snode01.theitroad.com     Ready    <none>   4m35s   v1.17.0
k8snode02.theitroad.com     Ready    <none>   2m4s    v1.17.0

步骤4：将Metrics Server部署到Kubernetes集群

Metrics Server是资源使用情况数据的群集范围内的聚合器。
它从摘要API收集指标，该摘要由Kubelet在每个节点上公开。
使用下面的教程进行部署：如何将Metrics Server部署到Kubernetes集群