kubeadm部署k8s1.9高可用集羣--4部署master節點

部署master節點

kubernetes master 節點包含的組件：

• kube-apiserver
• kube-scheduler
• kube-controller-manager

本文檔介紹部署一個三節點高可用 master 集羣的步驟，分別命名爲k8s-host1、k8s-host2、k8s-host3：

• k8s-host1：172.16.120.154
• k8s-host2：172.16.120.155
• k8s-host3：172.16.120.156

安裝docker

在每臺主機安裝docker。建議使用docker v1.12 , 可是 v1.11, v1.13 and 17.03 也能夠正常工做. 版本 17.06+ 可能工做, 可是沒有被k8s團隊測試過。
PS：kubelet設置的cgroup driver應該和Docker設置的cgroup driver一致。這邊統一爲systemd。

yum install -y docker
systemctl enable docker && systemctl start docker

安裝kubeadm, kubelet 和 kubectl

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
EOF
setenforce 0
yum install -y kubelet kubeadm kubectl
systemctl enable kubelet && systemctl start kubelet

• 經過運行命令setenforce 0 禁用selinux，主要爲了容許容器能夠訪問主機文件系統和pod networks的須要。
• Some users on RHEL/CentOS 7 have reported issues with traffic being routed incorrectly due to iptables being bypassed。因此須要執行下面命令：

cat <<EOF >  /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sysctl --system

安裝master

kubeadm init

kubeadm init --apiserver-advertise-address=172.16.120.200 --pod-network-cidr=192.168.0.0/16

• apiserver-advertise-address該參數通常指定爲haproxy+keepalived 的vip。
• pod-network-cidr 主要是在搭建pod network（calico）時候須要在init時候指定。

出現以下錯誤：

[root@k8s-node04 ~]# kubeadm init --apiserver-advertise-address=172.16.120.200 --pod-network-cidr=192.168.0.0/16

[init] Using Kubernetes version: v1.9.0
[init] Using Authorization modes: [Node RBAC]
[preflight] Running pre-flight checks.
        [WARNING FileExisting-crictl]: crictl not found in system path
[preflight] Some fatal errors occurred:
        [ERROR Swap]: running with swap on is not supported. Please disable swap
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`

解決辦法：
1：kubelet啓動參數增長--fail-swap-on=false

[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"
Environment="KUBELET_SYSTEM_PODS_ARGS=--pod-manifest-path=/etc/kubernetes/manifests --allow-privileged=true"
Environment="KUBELET_NETWORK_ARGS=--network-plugin=cni --cni-conf-dir=/etc/cni/net.d --cni-bin-dir=/opt/cni/bin"
Environment="KUBELET_DNS_ARGS=--cluster-dns=10.96.0.10 --cluster-domain=cluster.local"
Environment="KUBELET_AUTHZ_ARGS=--authorization-mode=Webhook --client-ca-file=/etc/kubernetes/pki/ca.crt"
Environment="KUBELET_CADVISOR_ARGS=--cadvisor-port=0"
Environment="KUBELET_CGROUP_ARGS=--cgroup-driver=systemd"
Environment="KUBELET_CERTIFICATE_ARGS=--rotate-certificates=true --cert-dir=/var/lib/kubelet/pki"
Environment="KUBELET_SWAP_ARGS=--fail-swap-on=false"
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_SYSTEM_PODS_ARGS $KUBELET_NETWORK_ARGS $KUBELET_DNS_ARGS $KUBELET_AUTHZ_ARGS $KUBELET_CADVISOR_ARGS $KUBELET_CGROUP_ARGS $KUBELET_CERTIFICATE_ARGS $KUBELET_EXTRA_ARGS $KUBELET_SWAP_ARGS

2：kubeadm init 參數增長ignore-preflight-errors

kubeadm init --apiserver-advertise-address=172.16.120.200  --pod-network-cidr=192.168.0.0/16 --ignore-preflight-errors 'Swap'

3：在物理機上可能並不會出現該問題。

最終安裝成功

[root@k8s-host1 manifests]# kubeadm init --apiserver-advertise-address=172.16.120.200  --pod-network-cidr=192.168.0.0/16 --ignore-preflight-errors 'Swap'
[init] Using Kubernetes version: v1.9.0
[init] Using Authorization modes: [Node RBAC]
[preflight] Running pre-flight checks.
        [WARNING Swap]: running with swap on is not supported. Please disable swap
        [WARNING FileExisting-crictl]: crictl not found in system path
[preflight] Starting the kubelet service
[certificates] Generated ca certificate and key.
[certificates] Generated apiserver certificate and key.
[certificates] apiserver serving cert is signed for DNS names [k8s-host1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 172.16.120.200]
[certificates] Generated apiserver-kubelet-client certificate and key.
[certificates] Generated sa key and public key.
[certificates] Generated front-proxy-ca certificate and key.
[certificates] Generated front-proxy-client certificate and key.
[certificates] Valid certificates and keys now exist in "/etc/kubernetes/pki"
[kubeconfig] Wrote KubeConfig file to disk: "admin.conf"
[kubeconfig] Wrote KubeConfig file to disk: "kubelet.conf"
[kubeconfig] Wrote KubeConfig file to disk: "controller-manager.conf"
[kubeconfig] Wrote KubeConfig file to disk: "scheduler.conf"
[controlplane] Wrote Static Pod manifest for component kube-apiserver to "/etc/kubernetes/manifests/kube-apiserver.yaml"
[controlplane] Wrote Static Pod manifest for component kube-controller-manager to "/etc/kubernetes/manifests/kube-controller-manager.yaml"
[controlplane] Wrote Static Pod manifest for component kube-scheduler to "/etc/kubernetes/manifests/kube-scheduler.yaml"
[etcd] Wrote Static Pod manifest for a local etcd instance to "/etc/kubernetes/manifests/etcd.yaml"
[init] Waiting for the kubelet to boot up the control plane as Static Pods from directory "/etc/kubernetes/manifests".
[init] This might take a minute or longer if the control plane images have to be pulled.
[apiclient] All control plane components are healthy after 30.002346 seconds
[uploadconfig] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[markmaster] Will mark node k8s-host1 as master by adding a label and a taint
[markmaster] Master k8s-host1 tainted and labelled with key/value: node-role.kubernetes.io/master=""
[bootstraptoken] Using token: 26ea24.cb987cb5cf6f29a6
[bootstraptoken] Configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstraptoken] Configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstraptoken] Configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstraptoken] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: kube-dns
[addons] Applied essential addon: kube-proxy

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 --token 26ea24.cb987cb5cf6f29a6 172.16.120.200:6443 --discovery-token-ca-cert-hash sha256:a2d5e0391695bb122d4a43dc951f93934a2aaa1360e00556401a49ea0ec2bdab

PS 須要記下 kubeadm join --token 26ea24.cb987cb5cf6f29a6 172.16.120.200:6443 --discovery-token-ca-cert-hash sha256:a2d5e0391695bb122d4a43dc951f93934a2aaa1360e00556401a49ea0ec2bdab，便於之後node加入到k8s集羣中。

將kube-apiserver指向上一節部署的etcd集羣

首先須要將上節生成的etcd ca等證書cp到mater主機的/etc/etcd/ssl/下

默認kubeadm安裝了一個etcd節點，非集羣，非加密，因此咱們必須對kube-apiserver.yaml作修改。
修改後的kube-apiserver.yaml：

apiVersion: v1
kind: Pod
metadata:
  annotations:
    scheduler.alpha.kubernetes.io/critical-pod: ""
  labels:
    component: kube-apiserver
    tier: control-plane
  name: kube-apiserver
  namespace: kube-system
spec:
  containers:
  - command:
    - kube-apiserver
    - --allow-privileged=true
    - --requestheader-username-headers=X-Remote-User
    - --requestheader-group-headers=X-Remote-Group
    - --requestheader-extra-headers-prefix=X-Remote-Extra-
    - --service-cluster-ip-range=10.96.0.0/12
    - --requestheader-client-ca-file=/etc/kubernetes/pki/front-proxy-ca.crt
    - --proxy-client-key-file=/etc/kubernetes/pki/front-proxy-client.key
    - --enable-bootstrap-token-auth=true
    - --service-account-key-file=/etc/kubernetes/pki/sa.pub
    - --tls-cert-file=/etc/kubernetes/pki/apiserver.crt
    - --kubelet-client-certificate=/etc/kubernetes/pki/apiserver-kubelet-client.crt
    - --kubelet-client-key=/etc/kubernetes/pki/apiserver-kubelet-client.key
    - --proxy-client-cert-file=/etc/kubernetes/pki/front-proxy-client.crt
    - --insecure-port=0
    - --admission-control=Initializers,NamespaceLifecycle,LimitRanger,ServiceAccount,DefaultStorageClass,DefaultTolerationSeconds,NodeRestriction,ResourceQuota
    - --requestheader-allowed-names=front-proxy-client
    - --advertise-address=172.16.120.200
    - --client-ca-file=/etc/kubernetes/pki/ca.crt
    - --secure-port=6443
    - --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname
    - --tls-private-key-file=/etc/kubernetes/pki/apiserver.key
    - --authorization-mode=Node,RBAC
    - --etcd-servers=https://172.16.120.151:2379,https://172.16.120.152:2379,https://172.16.120.153:2379
    - --etcd-cafile=/etc/etcd/ssl/ca.pem
    - --etcd-certfile=/etc/etcd/ssl/etcd.pem
    - --etcd-keyfile=/etc/etcd/ssl/etcd-key.pem
    image: gcr.io/google_containers/kube-apiserver-amd64:v1.9.0
    livenessProbe:
      failureThreshold: 8
      httpGet:
        host: 172.16.120.200
        path: /healthz
        port: 6443
        scheme: HTTPS
      initialDelaySeconds: 15
      timeoutSeconds: 15
    name: kube-apiserver
    resources:
      requests:
        cpu: 250m
    volumeMounts:
    - mountPath: /etc/kubernetes/pki
      name: k8s-certs
      readOnly: true
    - mountPath: /etc/ssl/certs
      name: ca-certs
      readOnly: true
    - mountPath: /etc/pki
      name: ca-certs-etc-pki
      readOnly: true
    - mountPath: /etc/etcd/ssl
      name: ca-certs-etc-etcd-ssl
      readOnly: true
  hostNetwork: true
  volumes:
  - hostPath:
      path: /etc/kubernetes/pki
      type: DirectoryOrCreate
    name: k8s-certs
  - hostPath:
      path: /etc/ssl/certs
      type: DirectoryOrCreate
    name: ca-certs
  - hostPath:
      path: /etc/pki
      type: DirectoryOrCreate
    name: ca-certs-etc-pki
  - hostPath:
      path: /etc/etcd/ssl
      type: DirectoryOrCreate
    name: ca-certs-etc-etcd-ssl
status: {}

注意添加了如下四項：

--etcd-cafile=/etc/etcd/ssl/ca.pem  
--etcd-certfile=/etc/etcd/ssl/etcd.pem  
--etcd-keyfile=/etc/etcd/ssl/etcd-key.pem    
--etcd-servers=https://172.16.120.151:2379,https://172.16.120.152:2379,https://172.16.120.153:2379
# 以及掛載
 - mountPath: /etc/etcd/ssl
      name: ca-certs-etc-etcd-ssl
      readOnly: true
      
 - hostPath:
      path: /etc/etcd/ssl
      type: DirectoryOrCreate
    name: ca-certs-etc-etcd-ssl

確認第一臺master三大組件都成功啓動

kubectl get componentstatuses
NAME                 STATUS    MESSAGE              ERROR
controller-manager   Healthy   ok
scheduler            Healthy   ok
etcd-1               Healthy   {"health": "true"}
etcd-0               Healthy   {"health": "true"}
etcd-2               Healthy   {"health": "true"}

安裝其餘主機

我通常的作法是，依舊使用kubeadm init --apiserver-advertise-address=172.16.120.200 --pod-network-cidr=192.168.0.0/16 --ignore-preflight-errors 'Swap'
主要目的是下載k8s相關組件docker鏡像等，其實就是讓kubeadm把容易忽略的工做都作了。

而後將第一臺/etc/kubernetes/下全部文件拷貝到其餘master主機對應目錄下，直至其餘機器master三大組件啓動成功。

至此一個完整的master高可用集羣搭建完畢。