使用kubeadm安装Kubernetes 1.6
环境准备
1192.168.61.41 node1
2192.168.61.42 node2
3192.168.61.43 node3
安装Docker 1.12
Kubernetes 1.6还没有针对docker 1.13和最新的docker 17.03上做测试和验证，所以这里安装Kubernetes官方推荐的Docker 1.12版本。
1yum install -y yum-utils
2
3yum-config-manager \
4 --add-repo \
5 https://docs.docker.com/v1.13/engine/installation/linux/repo_files/centos/docker.repo
6
7yum makecache fast
查看版本：
1yum list docker-engine.x86_64 --showduplicates |sort -r
2docker-engine.x86_64 1.13.1-1.el7.centos docker-main
3docker-engine.x86_64 1.12.6-1.el7.centos docker-main
4docker-engine.x86_64 1.11.2-1.el7.centos docker-main
安装1.12.6：
1yum install -y docker-engine-1.12.6
2
3systemctl start docker
4systemctl enable docker
系统配置
根据官方文档Installing Kubernetes on Linux with kubeadm 中的Limitations小节中的内容，对各节点系统做如下设置:
创建/etc/sysctl.d/k8s.conf文件，添加如下内容：
1net.bridge.bridge-nf-call-ip6tables = 1
2net.bridge.bridge-nf-call-iptables = 1
执行sysctl -p /etc/sysctl.d/k8s.conf使修改生效。
在/etc/hostname中修改各节点的hostname，在/etc/hosts中设置hostname对应非lo回环网卡ip:
1192.168.61.41 node1
2192.168.61.42 node2
3192.168.61.43 node3
安装kubeadm和kubelet
下面在各节点安装kubeadm和kubelet：
1cat <<EOF > /etc/yum.repos.d/kubernetes.repo
2[kubernetes]
3name=Kubernetes
4baseurl=http://yum.kubernetes.io/repos/kubernetes-el7-x86_64
5enabled=1
6gpgcheck=1
7repo_gpgcheck=1
8gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg
9 https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
10EOF
测试地址http://yum.kubernetes.io/repos/kubernetes-el7-x86_64是否可用，如果不可用需要科学上网。
1 curl http://yum.kubernetes.io/repos/kubernetes-el7-x86_64
查看kubeadm, kubelet, kubectl, kubernets-cni的最新版本：
1yum list kubeadm --showduplicates |sort -r
2kubeadm.x86_64 1.6.1-0 kubernetes
3kubeadm.x86_64 1.6.0-0 kubernetes
4
5yum list kubelet --showduplicates |sort -r
6kubelet.x86_64 1.6.1-0 kubernetes
7kubelet.x86_64 1.6.0-0 kubernetes
8kubelet.x86_64 1.5.4-0 kubernetes
9
10
11yum list kubectl --showduplicates |sort -r
12kubectl.x86_64 1.6.1-0 kubernetes
13kubectl.x86_64 1.6.0-0 kubernetes
14kubectl.x86_64 1.5.4-0 kubernetes
15
16
17yum list kubernets-cni --showduplicates |sort -r
18kubernetes-cni x86_64 0.5.1-0 kubernetes
kubeadm和kubelet已经是1.6.1，就是我们要安装的版本，直接安装即可：
1setenforce 0
2
3yum install -y kubelet kubeadm kubectl kubernetes-cni
4...
5Installed:
6 kubeadm.x86_64 0:1.6.1-0 kubectl.x86_64 0:1.6.1-0 kubelet.x86_64 0:1.6.1-0
7 kubernetes-cni.x86_64 0:0.5.1-0
8
9Dependency Installed:
10 ebtables.x86_64 0:2.0.10-15.el7 socat.x86_64 0:1.7.2.2-5.el7
11
12Complete!
1systemctl enable kubelet.service
初始化集群
接下来使用kubeadm初始化集群，选择node1作为Master Node，在node1上执行下面的命令：
1kubeadm init --kubernetes-version=v1.6.1 --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=192.168.61.41
注意到kubeadm init的
--kubernetes-version和--apiserver-advertise-address发生了变化，之前kuebadm 1.6.0-0.alpha是--use-kubernetes-version和--api-advertise-addresses。
因为我们选择flannel作为Pod网络插件，所以上面的命令指定--pod-network-cidr=10.244.0.0/16。
在集群初始化遇到问题，可以使用下面的命令进行清理后重新再初始化：
1kubeadm reset
2ifconfig cni0 down
3ip link delete cni0
4ifconfig flannel.1 down
5ip link delete flannel.1
6rm -rf /var/lib/cni/
kubeadm init执行成功后输出下面的信息：
1kubeadm init --kubernetes-version=v1.6.1 --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=192.168.61.41
2[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
3[init] Using Kubernetes version: v1.6.1
4[init] Using Authorization mode: RBAC
5[preflight] Running pre-flight checks
6[preflight] Starting the kubelet service
7[certificates] Generated CA certificate and key.
8[certificates] Generated API server certificate and key.
9[certificates] API Server serving cert is signed for DNS names [node0 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.61.41]
10[certificates] Generated API server kubelet client certificate and key.
11[certificates] Generated service account token signing key and public key.
12[certificates] Generated front-proxy CA certificate and key.
13[certificates] Generated front-proxy client certificate and key.
14[certificates] Valid certificates and keys now exist in "/etc/kubernetes/pki"
15[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf"
16[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
17[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
18[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
19[apiclient] Created API client, waiting for the control plane to become ready
20[apiclient] All control plane components are healthy after 14.583864 seconds
21[apiclient] Waiting for at least one node to register
22[apiclient] First node has registered after 6.008990 seconds
23[token] Using token: e7986d.e440de5882342711
24[apiconfig] Created RBAC rules
25[addons] Created essential addon: kube-proxy
26[addons] Created essential addon: kube-dns
27
28Your Kubernetes master has initialized successfully!
29
30To start using your cluster, you need to run (as a regular user):
31
32 sudo cp /etc/kubernetes/admin.conf $HOME/
33 sudo chown $(id -u):$(id -g) $HOME/admin.conf
34 export KUBECONFIG=$HOME/admin.conf
35
36You should now deploy a pod network to the cluster.
37Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
38 http://kubernetes.io/docs/admin/addons/
39
40You can now join any number of machines by running the following on each node
41as root:
42
43 kubeadm join --token e7986d.e440de5882342711 192.168.61.41:6443
Master Node初始化完成，使用kubeadm初始化的Kubernetes集群在Master节点上的核心组件：kube-apiserver, kube-scheduler, kube-controller-manager是以静态Pod的形式运行的。
1ls /etc/kubernetes/manifests/
2etcd.yaml kube-apiserver.yaml kube-controller-manager.yaml kube-scheduler.yaml
在/etc/kubernetes/manifests/目录里可以看到kube-apiserver, kube-scheduler, kube-controller-manager的定义文件。另外集群持久化存储etcd也是以单点静态Pod的形式运行的，对于etcd后边我们会把它切换成etcd集群，这里暂且不表。
查看一下kube-apiserver.yaml的内容：
1apiVersion: v1
2kind: Pod
3metadata:
4 creationTimestamp: null
5 labels:
6 component: kube-apiserver
7 tier: control-plane
8 name: kube-apiserver
9 namespace: kube-system
10spec:
11 containers:
12 - command:
13 - kube-apiserver
14 .......
15 - --insecure-port=0
注意到kube-apiserver的选项--insecure-port=0，也就是说kubeadm 1.6.0初始化的集群，kube-apiserver没有监听默认的http 8080端口。
所以我们使用kubectl get nodes会报The connection to the server localhost:8080 was refused - did you specify the right host or port?。
查看kube-apiserver的监听端口可以看到只监听了https的6443端口，
1netstat -nltp | grep apiserver
2tcp6 0 0 :::6443 :::* LISTEN 9831/kube-apiserver
为了使用kubectl访问apiserver，在~/.bash_profile中追加下面的环境变量：
1export KUBECONFIG=/etc/kubernetes/admin.conf
1source ~/.bash_profile
此时kubectl命令在master node上就好用了，查看一下当前机器中的Node：
1kubectl get nodes
2NAME STATUS AGE VERSION
3node0 NotReady 3m v1.6.1
安装Pod Network
接下来安装flannel network add-on：
1kubectl create -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel-rbac.yml
2kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
3serviceaccount "flannel" created
4configmap "kube-flannel-cfg" created
5daemonset "kube-flannel-ds" created
如果Node有多个网卡的话，参考flannel issues 39701，目前需要在kube-flannel.yml中使用--iface参数指定集群主机内网网卡的名称，否则可能会出现dns无法解析。需要将kube-flannel.yml下载到本地，flanneld启动参数加上--iface=<iface-name>
1......
2apiVersion: extensions/v1beta1
3kind: DaemonSet
4metadata:
5 name: kube-flannel-ds
6......
7containers:
8 - name: kube-flannel
9 image: quay.io/coreos/flannel:v0.7.0-amd64
10 command: [ "/opt/bin/flanneld", "--ip-masq", "--kube-subnet-mgr", "--iface=eth1" ]
11......
使用kubectl get pod --all-namespaces -o wide确保所有的Pod都处于Running状态。
1kubectl get pod --all-namespaces -o wide
使master node参与工作负载
使用kubeadm初始化的集群，出于安全考虑Pod不会被调度到Master Node上，也就是说Master Node不参与工作负载。
这里搭建的是测试环境可以使用下面的命令使Master Node参与工作负载：
1kubectl taint nodes --all node-role.kubernetes.io/master-
测试DNS
1kubectl run curl --image=radial/busyboxplus:curl -i --tty
2Waiting for pod default/curl-2421989462-vldmp to be running, status is Pending, pod ready: false
3Waiting for pod default/curl-2421989462-vldmp to be running, status is Pending, pod ready: false
4If you don't see a command prompt, try pressing enter.
5[ root@curl-2421989462-vldmp:/ ]$
进入后执行nslookup kubernetes.default确认解析正常。
1[ root@curl-2421989462-vldmp:/ ]$ nslookup kubernetes.default
2Server: 10.96.0.10
3Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local
4
5Name: kubernetes.default
6Address 1: 10.96.0.1 kubernetes.default.svc.cluster.local
测试OK后，删除掉curl这个Pod。
1kubectl delete deploy curl
向集群中添加节点
下面将node2和node3加入集群，分别在node2和node3上执行：
1kubeadm join --token e7986d.e440de5882342711 192.168.61.41:6443
2[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
3[preflight] Running pre-flight checks
4[discovery] Trying to connect to API Server "192.168.61.41:6443"
5[discovery] Created cluster-info discovery client, requesting info from "https://192.168.61.41:6443"
6[discovery] Cluster info signature and contents are valid, will use API Server "https://192.168.61.41:6443"
7[discovery] Successfully established connection with API Server "192.168.61.41:6443"
8[bootstrap] Detected server version: v1.6.1
9[bootstrap] The server supports the Certificates API (certificates.k8s.io/v1beta1)
10[csr] Created API client to obtain unique certificate for this node, generating keys and certificate signing request
11[csr] Received signed certificate from the API server, generating KubeConfig...
12[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
13
14Node join complete:
15* Certificate signing request sent to master and response
16 received.
17* Kubelet informed of new secure connection details.
18
19Run 'kubectl get nodes' on the master to see this machine join.
查看集群中节点：
1kubectl get nodes
2NAME STATUS AGE VERSION
3node1 Ready 12m v1.6.1
4node2 Ready 4m v1.6.1
5node3 Ready 2m v1.6.1
安装Dashboard插件
1wget https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/kubernetes-dashboard.yaml
2
3kubectl create -f kubernetes-dashboard.yaml
从http://NodeIp:NodePort访问dashboard，浏览器显示下面的错误：
1User "system:serviceaccount:kube-system:default" cannot list statefulsets.apps in the namespace "default". (get statefulsets.apps)
这是因为Kubernetes 1.6开始API Server启用了RBAC授权，当前的kubernetes-dashboard.yaml没有定义授权的ServiceAccount，所以访问API Server时被拒绝了。
根据https://github.com/kubernetes/dashboard/issues/1803中的内容临时授予system:serviceaccount:kube-system:default cluster_admin的角色，临时解决一下。
创建dashboard-rbac.yaml，定义system:serviceaccount:kube-system:default和ClusterRole cluster-admin绑定：
1kind: ClusterRoleBinding
2apiVersion: rbac.authorization.k8s.io/v1beta1
3metadata:
4 name: dashboard-admin
5roleRef:
6 apiGroup: rbac.authorization.k8s.io
7 kind: ClusterRole
8 name: cluster-admin
9subjects:
10- kind: ServiceAccount
11 name: default
12 namespace: kube-system
1 kubectl create -f dashboard-rbac.yml
在集群中运行Heapster
下面安装Heapster为集群添加使用统计和监控功能，为Dashboard添加仪表盘。
下载最新的Heapster到集群中的某个Node上。
1wget https://github.com/kubernetes/heapster/archive/v1.3.0.tar.gz
使用InfluxDB做为Heapster的后端存储，开始部署，中间会pull相关镜像，包含gcr.io/google_containers/heapster_grafana:v2.6.0-2
1tar -zxvf v1.3.0.tar.gz
2cd heapster-1.3.0/deploy/kube-config/influxdb
3
4kubectl create -f ./
5deployment "monitoring-grafana" created
6service "monitoring-grafana" created
7deployment "heapster" created
8service "heapster" created
9deployment "monitoring-influxdb" created
10service "monitoring-influxdb" created
最后确认所有的pod都处于running状态，打开Dashboard,集群的使用统计会以仪表盘的形式显示出来。