虽然网上有大量从零搭建K8S的文章，但大都针对老版本，若直接照搬去安装最新的1.20版本会遇到一堆问题。故此将我的安装步骤记录下来，希望能为读者提供copy and paste式的集群搭建帮助。
我是在腾讯云CentOS的2台服务器上，在不翻墙的情况下使用kubeadm（最简单的部署工具）搭建K8S集群。其中，容器网络使用flannel，最终安装好可以外网访问的2.0.4版本的dashboard。不走弯路的话，4步即可完成：
1、准备系统环境
对这2台新购的云虚拟机，都需要安装docker：
yum install docker -y
安装kubeadm前，需要先添加kubeadm的yum源：
cat > /etc/yum.repos.d/kubernetes.repo <<EOF
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
EOF
接着安装目前最新版的kubeadm：
yum install kubeadm-1.20.1-0.x86_64
其中，kubeadm依赖的kubelet（K8S最核心的组件）、kubectl、kubernetes-cni网络插件等会自动安装。
最后启用这2个服务：
systemctl enable kubelet.service
systemctl start docker.service
腾讯云主机默认已经将bridge-nf-call-iptables和ip_forward置为1，如果你的主机值为0，需要先将功能开启：
sysctl -w net.bridge.bridge-nf-call-iptables=1
sysctl -w net.ipv4.ip_forward=1
接着，针对部署K8S master节点的主机，还需要做些工作。由于腾讯云默认的主机名并不是域名格式（不符合master节点要求），所以需要修改为你自定义的域名。这需要2个步骤：
- 将设计好的主机名写入/etc/hostname文件；
- 将/etc/hosts中原主机名替换掉。
2、部署master节点
kubeadm的init命令即可初始化以单节点部署的master。为了避免翻墙，我 **使用了registry.aliyuncs.com/google_containers 源 **。虽然可以在kubeadm命令行中输入源，比如：
kubeadm init --image-repository registry.aliyuncs.com/google_containers
但将其写入资源编排文件更易维护，我将其命名为kubeadm.yaml：
apiVersion: kubeadm.k8s.io/v1beta2
imageRepository: registry.aliyuncs.com/google_containers
kind: ClusterConfiguration
kubernetesVersion: v1.20.1
networking:
podSubnet: 10.244.0.0/16
controllerManager:
ExtraArgs:
horizontal-pod-autoscaler-use-rest-clients: "true"
horizontal-pod-autoscaler-sync-period: "10s"
node-monitor-grace-period: "10s"
注意，这个编排文件有4个细节：
10.244.0.0/16
controllerManager
接着，使用编排文件执行init命令：
kubeadm init --config ./kubeadm.yaml
注意，执行成功后kubeadm会返回类似下面的字样：
Your Kubernetes control-plane has initialized successfully!
之后，还有2条重要的信息：
1、后续kubectl默认控制集群时，需要使用到CA密钥，通过TLS协议保障通讯的安全性。我们要通过下面3行命令拷贝密钥信息，这样，kubectl执行时会首先访问当前用户的.kube目录，使用这些授权信息访问集群：
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
2、之后添加worker节点时，要通过token才能保障安全性。因此，先把显示的这行命令保存下来：
kubeadm join 172.27.0.11:6443 --token xxxxxxxxxxxx \
--discovery-token-ca-cert-hash sha256:xxxxxxxxxxxxxxxxxxxxxxxx
3.部署flannel网络
flannel网络需要指定IP地址段，在上一步中已经通过编排文件设置为 10.244.0.0/16 。部署flannel只需要一行命令：
kubectl apply -f ./kube-flannel.yml
其中，由于原本可以直接下载的文件必须翻墙，所以我把文件内容列在下方，保存为上述命令的kube-flannel.yml文件（参见第5小节）：
此时，调用get pods命令，可以看到master节点的组件和flannel网络都牌Running状态：
[root@k8s]# kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-7f89b7bc75-g8c42 1/1 Running 0 118s
coredns-7f89b7bc75-z2p7c 1/1 Running 0 118s
etcd-taohui.tech 1/1 Running 0 2m6s
kube-apiserver-taohui.tech 1/1 Running 0 2m6s
kube-controller-manager-taohui.tech 1/1 Running 0 2m6s
kube-flannel-ds-kfzrg 1/1 Running 0 13s
kube-proxy-qbdz5 1/1 Running 0 118s
kube-scheduler-taohui.tech 1/1 Running 0 2m6s
接着，登入另一台服务器上，通过之前保存的kubeadm join命令，将其加入K8S集群。通过get nodes命令可以看到集群中已有2个节点：
# kubectl get nodes
NAME STATUS ROLES AGE VERSION
taohui.tech Ready control-plane,master 14h v1.20.0
workernode Ready <none> 12h v1.20.1
至此集群部署成功！如果有参数错误需要修改，你也可以在reset后重新init集群：
kubeadm reset
4.部署dashboard的
我们可以用以WEB页面的可视化dashboard，监控集群的状态。部署时同样面临翻墙和版本匹配的问题，这里我将2个镜像源替换后保存为dashboard.yaml编排文件（参见第6小节）：
kubectl apply -f dashboard.yaml
执行成功后，你可以查看到service：
# kubectl get svc -n kubernetes-dashboard
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
dashboard-metrics-scraper ClusterIP 10.100.6.83 <none> 8000/TCP 13h
kubernetes-dashboard ClusterIP 10.99.243.226 <none> 443/TCP 13h
注意，dashboard默认不允许外网访问。即使我们通过kubectl proxy允许外网访问，但dashboard又只允许HTTPS访问，这样kubeadm init时自签名的CA证书是不被浏览器承认的。我采用的方案是Nginx作为反向代理，使用Lets Encrypt提供的有效证书对外提供服务，再经由proxy_pass指令反向代理到kubectl proxy上，例如：
kubectl proxy --port=8888 --accept-hosts='^*$'
此时，本地可经由8888访问到dashboard。再通过Nginx访问它：
proxy_pass http://localhost:8888;
这样，当在外网根据我的域名访问如下URL：
https://mydomain/api/v1/namespaces/kubernetes-dashboard/services/https:kubernetes-dashboard:/proxy/#/login
就会展现2种登陆方式：
接下来采用token方式。首先要创建管理员帐户：
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: ServiceAccount
metadata:
name: admin-user
namespace: kubernetes-dashboard
EOF
执行完后，serviceaccount/admin-user用户已经创建。接着，将用户绑定已经存在的集群管理员角色：
cat <<EOF | kubectl apply -f -
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: admin-user
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-admin
subjects:
- kind: ServiceAccount
name: admin-user
namespace: kubernetes-dashboard
EOF
最后，获取可用户于访问的token：
kubectl -n kubernetes-dashboard describe secret $(kubectl -n kubernetes-dashboard get secret | grep admin-user | awk '{print $1}')
将token粘贴到登录页面，就可以看到dashboard了（下图是node页面）：
不
5、用于部署flannel网络的资源编排文件
---
apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
name: psp.flannel.unprivileged
annotations:
seccomp.security.alpha.kubernetes.io/allowedProfileNames: docker/default
seccomp.security.alpha.kubernetes.io/defaultProfileName: docker/default
apparmor.security.beta.kubernetes.io/allowedProfileNames: runtime/default
apparmor.security.beta.kubernetes.io/defaultProfileName: runtime/default
spec:
privileged: false
volumes:
- configMap
- secret
- emptyDir
- hostPath
allowedHostPaths:
- pathPrefix: "/etc/cni/net.d"
- pathPrefix: "/etc/kube-flannel"
- pathPrefix: "/run/flannel"
readOnlyRootFilesystem: false
# Users and groups
runAsUser:
rule: RunAsAny
supplementalGroups:
rule: RunAsAny
fsGroup:
rule: RunAsAny
# Privilege Escalation
allowPrivilegeEscalation: false
defaultAllowPrivilegeEscalation: false
# Capabilities
allowedCapabilities: ['NET_ADMIN', 'NET_RAW']
defaultAddCapabilities: []
requiredDropCapabilities: []
# Host namespaces
hostPID: false
hostIPC: false
hostNetwork: true
hostPorts:
- min: 0
max: 65535
# SELinux
seLinux:
# SELinux is unused in CaaSP
rule: 'RunAsAny'
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: flannel
rules:
- apiGroups: ['extensions']
resources: ['podsecuritypolicies']
verbs: ['use']
resourceNames: ['psp.flannel.unprivileged']
- apiGroups:
- ""
resources:
- pods
verbs:
- get
- apiGroups:
- ""
resources:
- nodes
verbs:
- list
- watch
- apiGroups:
- ""
resources:
- nodes/status
verbs:
- patch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: flannel
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: flannel
subjects:
- kind: ServiceAccount
name: flannel
namespace: kube-system
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: flannel
namespace: kube-system
---
kind: ConfigMap
apiVersion: v1
metadata:
name: kube-flannel-cfg
namespace: kube-system
labels:
tier: node
app: flannel
data:
cni-conf.json: |
{
"name": "cbr0",
"cniVersion": "0.3.1",
"plugins": [
{
"type": "flannel",
"delegate": {
"hairpinMode": true,
"isDefaultGateway": true
}
},
{
"type": "portmap",
"capabilities": {
"portMappings": true
}
}
]
}
net-conf.json: |
{
"Network": "10.244.0.0/16",
"Backend": {
"Type": "vxlan"
}
}
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: kube-flannel-ds
namespace: kube-system
labels:
tier: node
app: flannel
spec:
selector:
matchLabels:
app: flannel
template:
metadata:
labels:
tier: node
app: flannel
spec:
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
- key: kubernetes.io/os
operator: In
values:
- linux
hostNetwork: true
priorityClassName: system-node-critical
tolerations:
- operator: Exists
effect: NoSchedule
serviceAccountName: flannel
initContainers:
- name: install-cni
image: quay.io/coreos/flannel:v0.13.1-rc1
command:
- cp
args:
- -f
- /etc/kube-flannel/cni-conf.json
- /etc/cni/net.d/10-flannel.conflist
volumeMounts:
- name: cni
mountPath: /etc/cni/net.d
- name: flannel-cfg
mountPath: /etc/kube-flannel/
containers:
- name: kube-flannel
image: quay.io/coreos/flannel:v0.13.1-rc1
command:
- /opt/bin/flanneld
args:
- --ip-masq
- --kube-subnet-mgr
resources:
requests:
cpu: "100m"
memory: "50Mi"
limits:
cpu: "100m"
memory: "50Mi"
securityContext:
privileged: false
capabilities:
add: ["NET_ADMIN", "NET_RAW"]
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
volumeMounts:
- name: run
mountPath: /run/flannel
- name: flannel-cfg
mountPath: /etc/kube-flannel/
volumes:
- name: run
hostPath:
path: /run/flannel
- name: cni
hostPath:
path: /etc/cni/net.d
- name: flannel-cfg
configMap:
name: kube-flannel-cfg
6、用于部署dashboard的资源编排文件dashboard.yaml
# Copyright 2017 The Kubernetes Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
apiVersion: v1
kind: Namespace
metadata:
name: kubernetes-dashboard
---
apiVersion: v1
kind: ServiceAccount
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
---
kind: Service
apiVersion: v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
spec:
ports:
- port: 443
targetPort: 8443
selector:
k8s-app: kubernetes-dashboard
---
apiVersion: v1
kind: Secret
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-certs
namespace: kubernetes-dashboard
type: Opaque
---
apiVersion: v1
kind: Secret
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-csrf
namespace: kubernetes-dashboard
type: Opaque
data:
csrf: ""
---
apiVersion: v1
kind: Secret
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-key-holder
namespace: kubernetes-dashboard
type: Opaque
---
kind: ConfigMap
apiVersion: v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-settings
namespace: kubernetes-dashboard
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
rules:
# Allow Dashboard to get, update and delete Dashboard exclusive secrets.
- apiGroups: [""]
resources: ["secrets"]
resourceNames: ["kubernetes-dashboard-key-holder", "kubernetes-dashboard-certs", "kubernetes-dashboard-csrf"]
verbs: ["get", "update", "delete"]
# Allow Dashboard to get and update 'kubernetes-dashboard-settings' config map.
- apiGroups: [""]
resources: ["configmaps"]
resourceNames: ["kubernetes-dashboard-settings"]
verbs: ["get", "update"]
# Allow Dashboard to get metrics.
- apiGroups: [""]
resources: ["services"]
resourceNames: ["heapster", "dashboard-metrics-scraper"]
verbs: ["proxy"]
- apiGroups: [""]
resources: ["services/proxy"]
resourceNames: ["heapster", "http:heapster:", "https:heapster:", "dashboard-metrics-scraper", "http:dashboard-metrics-scraper"]
verbs: ["get"]
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
rules:
# Allow Metrics Scraper to get metrics from the Metrics server
- apiGroups: ["metrics.k8s.io"]
resources: ["pods", "nodes"]
verbs: ["get", "list", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: kubernetes-dashboard
subjects:
- kind: ServiceAccount
name: kubernetes-dashboard
namespace: kubernetes-dashboard
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: kubernetes-dashboard
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: kubernetes-dashboard
subjects:
- kind: ServiceAccount
name: kubernetes-dashboard
namespace: kubernetes-dashboard
---
kind: Deployment
apiVersion: apps/v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
spec:
replicas: 1
revisionHistoryLimit: 10
selector:
matchLabels:
k8s-app: kubernetes-dashboard
template:
metadata:
labels:
k8s-app: kubernetes-dashboard
spec:
containers:
- name: kubernetes-dashboard
image: registry.cn-shanghai.aliyuncs.com/jieee/dashboard:v2.0.4
imagePullPolicy: Always
ports:
- containerPort: 8443
protocol: TCP
args:
- --auto-generate-certificates
- --namespace=kubernetes-dashboard
# Uncomment the following line to manually specify Kubernetes API server Host
# If not specified, Dashboard will attempt to auto discover the API server and connect
# to it. Uncomment only if the default does not work.
# - --apiserver-host=http://my-address:port
volumeMounts:
- name: kubernetes-dashboard-certs
mountPath: /certs
# Create on-disk volume to store exec logs
- mountPath: /tmp
name: tmp-volume
livenessProbe:
httpGet:
scheme: HTTPS
path: /
port: 8443
initialDelaySeconds: 30
timeoutSeconds: 30
securityContext:
allowPrivilegeEscalation: false
readOnlyRootFilesystem: true
runAsUser: 1001
runAsGroup: 2001
volumes:
- name: kubernetes-dashboard-certs
secret:
secretName: kubernetes-dashboard-certs
- name: tmp-volume
emptyDir: {}
serviceAccountName: kubernetes-dashboard
nodeSelector:
"kubernetes.io/os": linux
# Comment the following tolerations if Dashboard must not be deployed on master
tolerations:
- key: node-role.kubernetes.io/master
effect: NoSchedule
---
kind: Service
apiVersion: v1
metadata:
labels:
k8s-app: dashboard-metrics-scraper
name: dashboard-metrics-scraper
namespace: kubernetes-dashboard
spec:
ports:
- port: 8000
targetPort: 8000
selector:
k8s-app: dashboard-metrics-scraper
---
kind: Deployment
apiVersion: apps/v1
metadata:
labels:
k8s-app: dashboard-metrics-scraper
name: dashboard-metrics-scraper
namespace: kubernetes-dashboard
spec:
replicas: 1
revisionHistoryLimit: 10
selector:
matchLabels:
k8s-app: dashboard-metrics-scraper
template:
metadata:
labels:
k8s-app: dashboard-metrics-scraper
annotations:
seccomp.security.alpha.kubernetes.io/pod: 'runtime/default'
spec:
containers:
- name: dashboard-metrics-scraper
image: registry.cn-shanghai.aliyuncs.com/jieee/metrics-scraper:v1.0.4
ports:
- containerPort: 8000
protocol: TCP
livenessProbe:
httpGet:
scheme: HTTP
path: /
port: 8000
initialDelaySeconds: 30
timeoutSeconds: 30
volumeMounts:
- mountPath: /tmp
name: tmp-volume
securityContext:
allowPrivilegeEscalation: false
readOnlyRootFilesystem: true
runAsUser: 1001
runAsGroup: 2001
serviceAccountName: kubernetes-dashboard
nodeSelector:
"kubernetes.io/os": linux
# Comment the following tolerations if Dashboard must not be deployed on master
tolerations:
- key: node-role.kubernetes.io/master
effect: NoSchedule
volumes:
- name: tmp-volume
emptyDir: {}
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