最近准备系统地学习一下 k8s，所以第一件事就是搭建环境，本篇文章就来记录一下自己在 CentOS 系统上搭建 k8s 环境的经历。
环境准备
虚拟机信息：
- 本地系统：win10
- 虚拟机软件：VirtualBox
- Linux 系统：CentOS7
- 虚拟机节点（至少2U2G）：k8s-master(192.168.31.44)、k8s-node01、k8s-node02
k8s 相关信息：
- docker 版本：docker-ce 18.09.9
- k8s 版本：v1.16.0
- 准备国内镜像源
安装 docker-ce（所有机器）
给所有的虚拟机都安装 docker-ce，选择的版本为 18.09.9，这里我使用了我之前写的安装 docker 的文章里面使用的命令，直接写成了脚本 install_docker.sh，内容如下：
#/bin/bash # 使用root用户安装docker DOCKER_VERSION=docker-ce-18.09.9-3.el7 DOCKER_REGISTRY=https://registry.docker-cn.com YUN_REPO=http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo # 卸载原有的 docker yum remove docker \ docker-client \ docker-client-latest \ docker-common \ docker-latest \ docker-latest-logrotate \ docker-logrotate \ docker-engine # 清理残留目录 rm -rf /var/lib/docker rm -rf /var/run/docker # 添加阿里yum源，并更新yum索引 yum install -y yum-utils yum-config-manager --add-repo ${YUN_REPO} yum makecache fast # 安装docker-ce,可以自定义版本 yum install -y ${DOCKER_VERSION} # 设置为系统服务并启动docker systemctl enable docker && systemctl start docker # 设置镜像仓库源 cat <<EOF >/etc/docker/daemon.json { "registry-mirrors": ["${DOCKER_REGISTRY}"], "exec-opts": ["native.cgroupdriver=systemd"] } EOF # 重启docker systemctl daemon-reload systemctl restart docker
k8s 环境配置（所有机器）
安装 docker-ce 之后，需要给虚拟机执行一些命令准备好环境，这些步骤我写到脚本 k8s_env.sh 里面了，内容如下：
#/bin/bash # 关闭防火墙 systemctl disable firewalld systemctl stop firewalld # 关闭selinux # 临时禁用selinux setenforce 0 # 永久关闭 修改/etc/sysconfig/selinux文件设置 sed -i 's/SELINUX=permissive/SELINUX=disabled/' /etc/sysconfig/selinux sed -i "s/SELINUX=enforcing/SELINUX=disabled/g" /etc/selinux/config # 禁用交换分区 swapoff -a # 永久禁用，打开/etc/fstab注释掉swap那一行。 sed -i 's/.*swap.*/#&/' /etc/fstab # 修改内核参数 cat <<EOF >/etc/sysctl.d/k8s.conf net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 EOF sysctl --system
安装k8s v1.16.0 （master节点）
安装完 docker 并执行了 k8s 准备条件之后，需要在 k8s 主节点上面执行下面命令安装 k8s，版本为 v1.16.0，我将所有命令写到脚本 k8s_install_master.sh 里面了，这个脚本需要传入一个参数，也就是主节点的IP地址，内容如下：
#/bin/bash # 脚本执行必须传入一个参数，就是k8s主节点IP地址 master_ip=$1 if [ "$master_ip" == "" ]; then echo "Error: please set master ip." & exit 210 else echo "master ip is $master_ip" fi K8S_BASEURL=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/ K8S_GPGKEY="https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg" POD_NETWORD=10.244.0.0 # 执行配置k8s阿里云源 cat <<EOF >/etc/yum.repos.d/kubernetes.repo [kubernetes] name=Kubernetes baseurl=${K8S_BASEURL} enabled=1 gpgcheck=1 repo_gpgcheck=1 gpgkey=${K8S_GPGKEY} EOF # 安装kubeadm、kubectl、kubelet yum install -y kubectl-1.16.0-0 kubeadm-1.16.0-0 kubelet-1.16.0-0 # 启动kubelet服务 systemctl enable kubelet && systemctl start kubelet # 安装初始化镜像，参数详解查看文档 https://kubernetes.io/zh/docs/reference/setup-tools/kubeadm/kubeadm-init/ kubeadm init --image-repository registry.aliyuncs.com/google_containers --kubernetes-version v1.16.0 --apiserver-advertise-address ${master_ip} --pod-network-cidr=${POD_NETWORD}/16 --token-ttl 0 # kubeadm init 执行完成之后需要执行的操作 mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config
主节点安装完成后，可以看到如下输出，最后一句就是给了一条命令，在 node 节点执行该命令就可以加入 k8s 集群中，以后也可以通过在主节点执行命令来查询 kubeadm token create --print-join-command。
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) $HOME/.kube/config
You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
https://kubernetes.io/docs/concepts/cluster-administration/addons/
Then you can join any number of worker nodes by running the following on each as root:
kubeadm join 192.168.31.44:6443 --token i0nitb.9dx9gqqmjc25cl4v \
--discovery-token-ca-cert-hash sha256:c7deb13d6544fe360e70fdc7b1c3140d2d5c1f98fc0e5d4c8deccadd91adf726
安装k8s v1.16.0 （node 节点）
node 节点安装 k8s 比主节点的内容稍微少一点，但是版本信息一样，我写成了脚本 k8s_install_node.sh，内容如下：
#/bin/bash K8S_BASEURL=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/ K8S_GPGKEY="https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg" cat <<EOF >/etc/yum.repos.d/kubernetes.repo [kubernetes] name=Kubernetes baseurl=${K8S_BASEURL} enabled=1 gpgcheck=1 repo_gpgcheck=1 gpgkey=${K8S_GPGKEY} EOF # 安装kubeadm、kubectl、kubelet yum install -y kubeadm-1.16.0-0 kubelet-1.16.0-0 # 启动kubelet服务 systemctl enable kubelet && systemctl start kubelet # 加入集群，如果这里不知道加入集群的命令，可以登录master节点，使用kubeadm token create --print-join-command 来获取 #kubeadm join 192.168.31.213:6443 --token 7172cu.ouhrkxvv1wj5gdfr --discovery-token-ca-cert-hash sha256:b3613871b6812b09351f7501517149e48562927efc3a2f7b70f7bff29bfc697c
node 节点安装完 k8s 之后，需要在主节点上执行命令 kubeadm token create --print-join-command 查询出加入 k8s 集群的命令，在 node 上面执行该命令即可加入到集群中，如：
[root@k8s-master alex]# kubeadm token create --print-join-command kubeadm join 192.168.31.44:6443 --token dbyk42.jt15226b6xd4rfvo --discovery-token-ca-cert-hash sha256:c7deb13d6544fe360e70fdc7b1c3140d2d5c1f98fc0e5d4c8deccadd91adf726
到这里，主节点和 node 节点都已经安装好 k8s 了，这个时候在主节点执行命令 kubectl get nodes 即可查看到集群的节点信息：
[root@k8s-master alex]# kubectl get nodes NAME STATUS ROLES AGE VERSION k8s-master NotReady master 13m v1.16.0 k8s-node01 NotReady <none> 97s v1.16.0 k8s-node02 NotReady <none> 7s v1.16.0
这里可以看到，1个主节点，两个 node 节点，正是我这里搭建的 k8s 集群，但是这里三个节点的状态都是 NotReady，所以，很显然，环境还没有完全搭建好。
安装 flannel（master节点）
k8s 安装完之后状态是 NotReady 这个可以当做一个问题去网上搜索解决方案，我这里写的也只是我看到的解决方案之一，也就是通过安装 flannel 来解决。
其实就是需要一个 yaml 文件，官方地址是
--- 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' ] 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/v1beta1 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/v1beta1 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-amd64 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: beta.kubernetes.io/os operator: In values: - linux - key: beta.kubernetes.io/arch operator: In values: - amd64 hostNetwork: true tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: quay.io/coreos/flannel:v0.11.0-amd64 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:v0.11.0-amd64 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" ] 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 --- apiVersion: apps/v1 kind: DaemonSet metadata: name: kube-flannel-ds-arm64 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: beta.kubernetes.io/os operator: In values: - linux - key: beta.kubernetes.io/arch operator: In values: - arm64 hostNetwork: true tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: quay.io/coreos/flannel:v0.11.0-arm64 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:v0.11.0-arm64 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" ] 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 --- apiVersion: apps/v1 kind: DaemonSet metadata: name: kube-flannel-ds-arm 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: beta.kubernetes.io/os operator: In values: - linux - key: beta.kubernetes.io/arch operator: In values: - arm hostNetwork: true tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: quay.io/coreos/flannel:v0.11.0-arm 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:v0.11.0-arm 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" ] 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 --- apiVersion: apps/v1 kind: DaemonSet metadata: name: kube-flannel-ds-ppc64le 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: beta.kubernetes.io/os operator: In values: - linux - key: beta.kubernetes.io/arch operator: In values: - ppc64le hostNetwork: true tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: quay.io/coreos/flannel:v0.11.0-ppc64le 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:v0.11.0-ppc64le 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" ] 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 --- apiVersion: apps/v1 kind: DaemonSet metadata: name: kube-flannel-ds-s390x 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: beta.kubernetes.io/os operator: In values: - linux - key: beta.kubernetes.io/arch operator: In values: - s390x hostNetwork: true tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: quay.io/coreos/flannel:v0.11.0-s390x 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:v0.11.0-s390x 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" ] 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
将这个文件放到主节点任意目录，然后执行下面命令进行安装即可：
kubectl apply -f kube-flannel.yml
执行之后需要等待一段时间，然后再次查询 k8s 集群状态就可以看到状态都编程 Ready 了，至此，k8s 环境也就搭建完成了。
[root@k8s-master alex]# kubectl get nodes NAME STATUS ROLES AGE VERSION k8s-master Ready master 32m v1.16.0 k8s-node01 Ready <none> 20m v1.16.0 k8s-node02 Ready <none> 18m v1.16.0
这个时候可以启动一个简单的服务来验证一下 k8s 环境，下面是我提供的一个简单的 nginx 服务部署的编排，执行 kubectl apply -f nginx.yml 即可启动服务：
--- apiVersion: apps/v1 # 资源api接口版本 kind: Deployment # 资源类型 metadata: # 元数据 name: nginx-deployment # 资源名 spec: # 详情 replicas: 2 # 副本数 selector: # 选择标签 matchLabels: # 标签匹配 app: nginx-server # 定义要匹配的标签，下面pod中必须有这个标签 template: # pod模板 metadata: # pod详情 labels: # 定义标签 app: nginx-server # pod标签 spec: # pod详情 containers: # 容器 - name: nginx # 容器名称 image: nginx:1.7.9 # 容器镜像 ports: - name: http containerPort: 80 # 容器暴露端口 --- apiVersion: v1 kind: Service metadata: name: simple-service spec: ports: - name: nginx-port port: 80 # app服务的端口 protocol: TCP targetPort: 8080 # 暴露给pod的端口 nodePort: 31080 # 暴露给node的端口，也就是k8s节点 type: NodePort selector: app: nginx-server
遇到的问题
安装完 flannel 之后 node 节点的状态依然是 NotReady
定位和解决方案如下:
- 查看 node 节点日志
cat /var/log/messages，可以看到类似如下日志：
Mar 21 14:43:01 centos-4 kubelet: W0321 14:43:01.075369 4742 cni.go:237] Unable to update cni config: no networks found in /etc/cni/net.d Mar 21 14:43:03 centos-4 kubelet: E0321 14:43:03.523469 4742 kubelet.go:2187] Container runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni config uninitialized
将该日志拿去搜索，可以得知问题的原因在于 node 节点下载 flannel 镜像失败，网上也给了定位步骤，比如主节点执行命令 'kubectl get pods -o wide -n kube-system' 查看 pod 状态
[root@k8s-master alex]# kubectl get pods -o wide -n kube-system NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES coredns-58cc8c89f4-6svdn 1/1 Running 0 28m 10.244.2.3 k8s-node02 <none> <none> coredns-58cc8c89f4-gm78v 1/1 Running 0 28m 10.244.2.2 k8s-node02 <none> <none> etcd-k8s-master 1/1 Running 0 27m 192.168.31.44 k8s-master <none> <none> kube-apiserver-k8s-master 1/1 Running 0 27m 192.168.31.44 k8s-master <none> <none> kube-controller-manager-k8s-master 1/1 Running 0 27m 192.168.31.44 k8s-master <none> <none> kube-flannel-ds-amd64-7tnhr 1/1 Running 0 3m52s 192.168.31.148 k8s-node02 <none> <none> kube-flannel-ds-amd64-hlqpt 0/1 Init:ImagePullBackOff 0 3m52s 192.168.31.201 k8s-node01 <none> <none> kube-flannel-ds-amd64-j5m5n 1/1 Running 0 3m52s 192.168.31.44 k8s-master <none> <none> kube-proxy-95jjd 1/1 Running 0 15m 192.168.31.148 k8s-node02 <none> <none> kube-proxy-ckq5c 1/1 Running 0 28m 192.168.31.44 k8s-master <none> <none> kube-proxy-dv2fz 1/1 Running 0 16m 192.168.31.201 k8s-node01 <none> <none> kube-scheduler-k8s-master 1/1 Running 0 27m 192.168.31.44 k8s-master <none> <none>
这里可以看到果然有个 pod 的状态是 Init:ImagePullBackOff 也就是下载镜像失败，这也即是为什么有的人把 kube-flannel.yml 文件中镜像地址改了的原因，就是为了避免镜像下载失败。
问题知道了，就可以解决，直接去失败的 node 节点上面手动拉取镜像即可（也可以再等等，因为其他节点可以下载，说明网络是通的）。
参考文章
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zxcvbnm
1 楼 - 2 周，6天前
好棒哇