1. 背景
一直认为边看文档边实操是入门项目最快的方式，至于熟悉这个项目就得阅读源码。
Kubernetes 安装在不同环境还是有不同差异，由于国内网络限制，按照Kubernetes官网会遇到一些问题。根据遇到的问题，本人列出成功搭建Kubernetes环境过程。
1.1 系统环境
- 系统: centos7.5
- 系统参数: 4核 8G 100T磁盘
- Docker版本：1.18.3
- Kubernetes版本：1.13.3
- 主机信息
| 主机名 | IP | 角色 |
|---|---|---|
| K8s-master | 10.0.220.15 | K8s主节点 |
| K8s-node01 | 10.0.220.65 | K8s从节点01 |
| K8s-node02 | 10.0.220.111 | K8s从节点02 |
2. 搭建过程
2.1 物理节点配置（不区分物理机和虚拟机）
2.1.1 关闭防火墙
关于防火墙的原因（nftables后端兼容性问题，产生重复的防火墙规则）
The iptables tooling can act as a compatibility layer, behaving like iptables but actually configuring nftables. This nftables backend is not compatible with the current kubeadm packages: it causes duplicated firewall rules and breakskube-proxy.
所有节点都执行命令：
systemctl disable firewalld.service
systemctl disable firewalld.service
2.1.2 关闭SELinux
Selinux是一套白名单机制，为了安全对服务、文件、端口设置都有严格的限制，除非对selinux非常熟，一般都是关掉selinux。
关于k8s关闭selinux的原因（关闭selinux以允许容器访问宿主机的文件系统）
Setting SELinux in permissive mode by runningsetenforce 0andsed ...effectively disables it. This is required to allow containers to access the host filesystem, which is needed by pod networks for example. You have to do this until SELinux support is improved in the kubelet.
所有节点都执行命令：
setenforce 0
vi /etc/selinux/config
SELINUX=disabled
2.1.3 关闭Swap
k8s 目前必须关闭swap，主要是因为社区提出的issue: https://github.com/kubernetes/kubernetes/issues/53533
本人总结原因是当物理节点内存耗尽时，kubelet 组件无法handle memory eviction。
所有节点都执行命令：
swapoff -a
2.1.4 配置hostname
为了用户方便知道物理节点角色，我们为设置静态hostname。
三个节点分别执行以下三条命令：
hostnamectl --static set-hostname k8s-master
hostnamectl --static set-hostname k8s-node01
hostnamectl --static set-hostname k8s-node02
设置hosts文件
三个节点都添加同样的hosts内容：
10.0.220.15 k8s-master
10.0.220.65 k8s-node01
10.0.220.111 k8s-node02
2.1.5 配置免密
三个节点相互配置免密（原因在文档中还未找到）
过程不赘述，网上文档很多。
2.1.5 设置内核参数
将桥接的IPv4流量传递到iptables的链
所有节点都执行命令：
[root@k8s-master ~]# cat <<EOF > /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
EOF
sysctl –-system
2.1.6 安装docker
设置yum源
三个节点都执行：
cd /etc/yum.repos.d/
wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
安装指定docker版本
三个节点都执行：
yum -y install docker-ce-18.06.1.ce-3.el7
将docker进程设置为服务
三个节点都执行：
systemctl enable docker
systemctl start docker
查看docker版本
三个节点都执行：
docker --version
2.2 安装Kubernetes
2.2.1 设置Kubernetes Yaml 源
三个节点都执行：(写文件)
cat /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
2.2.2 安装Kubernetes指定版本
本文采用1.13.3版本
三个节点都执行：
yum install -y kubelet-1.13.3 kubeadm-1.13.3 kubectl-1.13.3 kubernetes-cni-0.6.0-0
2.2.3 拉取镜像
Kubernetes 系统本身有很多镜像，由于网络限制，本人找的镜像基本都是国内的。
docker pull mirrorgooglecontainers/kube-apiserver:v1.13.3
docker pull mirrorgooglecontainers/kube-controller-manager:v1.13.3
docker pull mirrorgooglecontainers/kube-scheduler:v1.13.3
docker pull mirrorgooglecontainers/kube-proxy:v1.13.3
docker pull mirrorgooglecontainers/pause:3.1
docker pull mirrorgooglecontainers/etcd:3.2.24
docker pull coredns/coredns:1.2.6
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/flannel:v0.10.0-amd64
docker tag mirrorgooglecontainers/kube-apiserver:v1.13.3 k8s.gcr.io/kube-apiserver:v1.13.3
docker tag mirrorgooglecontainers/kube-controller-manager:v1.13.3 k8s.gcr.io/kube-controller-manager:v1.13.3
docker tag mirrorgooglecontainers/kube-scheduler:v1.13.3 k8s.gcr.io/kube-scheduler:v1.13.3
docker tag mirrorgooglecontainers/kube-proxy:v1.13.3 k8s.gcr.io/kube-proxy:v1.13.3
docker tag mirrorgooglecontainers/pause:3.1 k8s.gcr.io/pause:3.1
docker tag mirrorgooglecontainers/etcd:3.2.24 k8s.gcr.io/etcd:3.2.24
docker tag coredns/coredns:1.2.6 k8s.gcr.io/coredns:1.2.6
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/flannel:v0.10.0-amd64 quay.io/coreos/flannel:v0.10.0-amd64
docker rmi mirrorgooglecontainers/kube-apiserver:v1.13.3
docker rmi mirrorgooglecontainers/kube-controller-manager:v1.13.3
docker rmi mirrorgooglecontainers/kube-scheduler:v1.13.3
docker rmi mirrorgooglecontainers/kube-proxy:v1.13.3
docker rmi mirrorgooglecontainers/pause:3.1
docker rmi mirrorgooglecontainers/etcd:3.2.24
docker rmi coredns/coredns:1.2.6
docker rmi registry.cn-shenzhen.aliyuncs.com/cp_m/flannel:v0.10.0-amd64
t
2.2.4 启动kubelet并设置为服务
* 三个节点都执行：
systemctl enable kubelet
systemctl start kubelet
2.2.5 初始化k8s master 节点
在master节点上执行：
kubeadm init --kubernetes-version=v1.13.3 --apiserver-advertise-address 10.0.220.15 --pod-network-cidr=10.244.0.0/16
- --apiserver-advertise-address：指定用 Master 的哪个IP地址与 Cluster的其他节点通信（一定要对应好master 节点IP地址）
- --service-cidr：指定Service网络的范围，即负载均衡VIP使用的IP地址段
- --pod-network-cidr：指定Pod网络的范围，即Pod的IP地址段
- --image-repository：Kubenetes默认Registries地址是 k8s.gcr.io，在国内并不能访问 gcr.io，在1.13版本中我们可以增加-image-repository参数，默认值是 k8s.gcr.io，将其指定为阿里云镜像地址：registry.aliyuncs.com/google_containers。
- --kubernetes-version=v1.13.3：指定要安装的版本号。
- --ignore-preflight-errors=：忽略运行时的错误，例如上面目前存在[ERROR NumCPU]和[ERROR Swap]，忽略这两个报错就是增加--ignore-preflight-errors=NumCPU 和--ignore-preflight-errors=Swap的配置即可。
初始化的结果：
Your Kubernetes master 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/
You can now join any number of machines by running the following on each node
as root:
kubeadm join 10.0.220.15:6443 --token i8nxlt.ox0bzax19jak1tyq --discovery-token-ca-cert-hash sha256:02e8fd59a30c53e792f5f822409762bfab5aef329fd24c48f994a20f752c5738
2.2.6 添加node节点
按照上面提示，我们添加node节点：
两个node节点都执行：
kubeadm join 10.0.220.15:6443 --token i8nxlt.ox0bzax19jak1tyq --discovery-token-ca-cert-hash sha256:02e8fd59a30c53e792f5f822409762bfab5aef329fd24c48f994a20f752c5738
2.2.7 配置kubectl
kubectl是用户常用的工具，使用kubectl需要有apiserver权限，我们执行下面命令
master节点执行：
echo "export KUBECONFIG=/etc/kubernetes/admin.conf" >> /etc/profile
source /etc/profile
echo $KUBECONFIG
2.2.3 配置网络
kubernetes 通信有很多网络模型，常用的是cailco和flannel，下面我们选择flannel网络。
master 执行：
kubectl apply -f kube-flannel.yaml
文件如下：kube-flannel.yaml
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: flannel
rules:
- 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",
"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: extensions/v1beta1
kind: DaemonSet
metadata:
name: kube-flannel-ds-amd64
namespace: kube-system
labels:
tier: node
app: flannel
spec:
template:
metadata:
labels:
tier: node
app: flannel
spec:
hostNetwork: true
nodeSelector:
beta.kubernetes.io/arch: amd64
tolerations:
- operator: Exists
effect: NoSchedule
serviceAccountName: flannel
initContainers:
- name: install-cni
image: quay.io/coreos/flannel:v0.10.0-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:v0.10.0-amd64
command:
- /opt/bin/flanneld
args:
- --ip-masq
- --kube-subnet-mgr
resources:
requests:
cpu: "100m"
memory: "50Mi"
limits:
cpu: "100m"
memory: "50Mi"
securityContext:
privileged: true
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
volumeMounts:
- name: run
mountPath: /run
- name: flannel-cfg
mountPath: /etc/kube-flannel/
volumes:
- name: run
hostPath:
path: /run
- name: cni
hostPath:
path: /etc/cni/net.d
- name: flannel-cfg
configMap:
name: kube-flannel-cfg
---
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
name: kube-flannel-ds-arm64
namespace: kube-system
labels:
tier: node
app: flannel
spec:
template:
metadata:
labels:
tier: node
app: flannel
spec:
hostNetwork: true
nodeSelector:
beta.kubernetes.io/arch: arm64
tolerations:
- operator: Exists
effect: NoSchedule
serviceAccountName: flannel
initContainers:
- name: install-cni
image: quay.io/coreos/flannel:v0.10.0-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:v0.10.0-arm64
command:
- /opt/bin/flanneld
args:
- --ip-masq
- --kube-subnet-mgr
resources:
requests:
cpu: "100m"
memory: "50Mi"
limits:
cpu: "100m"
memory: "50Mi"
securityContext:
privileged: true
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
volumeMounts:
- name: run
mountPath: /run
- name: flannel-cfg
mountPath: /etc/kube-flannel/
volumes:
- name: run
hostPath:
path: /run
- name: cni
hostPath:
path: /etc/cni/net.d
- name: flannel-cfg
configMap:
name: kube-flannel-cfg
---
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
name: kube-flannel-ds-arm
namespace: kube-system
labels:
tier: node
app: flannel
spec:
template:
metadata:
labels:
tier: node
app: flannel
spec:
hostNetwork: true
nodeSelector:
beta.kubernetes.io/arch: arm
tolerations:
- operator: Exists
effect: NoSchedule
serviceAccountName: flannel
initContainers:
- name: install-cni
image: quay.io/coreos/flannel:v0.10.0-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:v0.10.0-arm
command:
- /opt/bin/flanneld
args:
- --ip-masq
- --kube-subnet-mgr
resources:
requests:
cpu: "100m"
memory: "50Mi"
limits:
cpu: "100m"
memory: "50Mi"
securityContext:
privileged: true
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
volumeMounts:
- name: run
mountPath: /run
- name: flannel-cfg
mountPath: /etc/kube-flannel/
volumes:
- name: run
hostPath:
path: /run
- name: cni
hostPath:
path: /etc/cni/net.d
- name: flannel-cfg
configMap:
name: kube-flannel-cfg
---
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
name: kube-flannel-ds-ppc64le
namespace: kube-system
labels:
tier: node
app: flannel
spec:
template:
metadata:
labels:
tier: node
app: flannel
spec:
hostNetwork: true
nodeSelector:
beta.kubernetes.io/arch: ppc64le
tolerations:
- operator: Exists
effect: NoSchedule
serviceAccountName: flannel
initContainers:
- name: install-cni
image: quay.io/coreos/flannel:v0.10.0-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:v0.10.0-ppc64le
command:
- /opt/bin/flanneld
args:
- --ip-masq
- --kube-subnet-mgr
resources:
requests:
cpu: "100m"
memory: "50Mi"
limits:
cpu: "100m"
memory: "50Mi"
securityContext:
privileged: true
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
volumeMounts:
- name: run
mountPath: /run
- name: flannel-cfg
mountPath: /etc/kube-flannel/
volumes:
- name: run
hostPath:
path: /run
- name: cni
hostPath:
path: /etc/cni/net.d
- name: flannel-cfg
configMap:
name: kube-flannel-cfg
---
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
name: kube-flannel-ds-s390x
namespace: kube-system
labels:
tier: node
app: flannel
spec:
template:
metadata:
labels:
tier: node
app: flannel
spec:
hostNetwork: true
nodeSelector:
beta.kubernetes.io/arch: s390x
tolerations:
- operator: Exists
effect: NoSchedule
serviceAccountName: flannel
initContainers:
- name: install-cni
image: quay.io/coreos/flannel:v0.10.0-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:v0.10.0-s390x
command:
- /opt/bin/flanneld
args:
- --ip-masq
- --kube-subnet-mgr
resources:
requests:
cpu: "100m"
memory: "50Mi"
limits:
cpu: "100m"
memory: "50Mi"
securityContext:
privileged: true
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
volumeMounts:
- name: run
mountPath: /run
- name: flannel-cfg
mountPath: /etc/kube-flannel/
volumes:
- name: run
hostPath:
path: /run
- name: cni
hostPath:
path: /etc/cni/net.d
- name: flannel-cfg
configMap:
name: kube-flannel-cfg
3. 安装校验
查看pod
kubectl get pods --all-namespaces -o wide
查看node
kubectl get nodes
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