使用 kubeadm 搭建 kubernetes1.10 集群

PS:所有節點安裝之前記得先把鏡像准備好，否者將無法啟動，也不報錯。

$ cat /etc/hosts
192.168.11.1 master
192.168.11.2 node

禁用防火牆：

$ systemctl stop firewalld
$ systemctl disable firewalld

禁用SELINUX：

$ setenforce 0
$ cat /etc/selinux/config
SELINUX=disabled

創建/etc/sysctl.d/k8s.conf文件，添加如下內容：

net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1

執行如下命令使修改生效：

$ modprobe br_netfilter
$ sysctl -p /etc/sysctl.d/k8s.conf

鏡像

如果你的節點上面有科學上網的工具，可以忽略這一步，我們需要提前將所需的gcr.io上面的鏡像下載到節點上面，當然前提條件是你已經成功安裝了docker。

master節點，執行下面的命令：

docker pull registry-vpc.cn-shenzhen.aliyuncs.com/cp_m/kube-apiserver-amd64:v1.10.0
docker pull registry-vpc.cn-shenzhen.aliyuncs.com/cp_m/kube-scheduler-amd64:v1.10.0
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/kube-controller-manager-amd64:v1.10.0
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/kube-proxy-amd64:v1.10.0
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/k8s-dns-kube-dns-amd64:1.14.8
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/k8s-dns-dnsmasq-nanny-amd64:1.14.8
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/k8s-dns-sidecar-amd64:1.14.8
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/etcd-amd64:3.1.12
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/flannel:v0.10.0-amd64
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/pause-amd64:3.1

 

docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/kube-apiserver-amd64:v1.10.0 k8s.gcr.io/kube-apiserver-amd64:v1.10.0
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/kube-scheduler-amd64:v1.10.0 k8s.gcr.io/kube-scheduler-amd64:v1.10.0
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/kube-controller-manager-amd64:v1.10.0 k8s.gcr.io/kube-controller-manager-amd64:v1.10.0
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/kube-proxy-amd64:v1.10.0 k8s.gcr.io/kube-proxy-amd64:v1.10.0
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/k8s-dns-kube-dns-amd64:1.14.8 k8s.gcr.io/k8s-dns-kube-dns-amd64:1.14.8
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/k8s-dns-dnsmasq-nanny-amd64:1.14.8 k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64:1.14.8
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/k8s-dns-sidecar-amd64:1.14.8 k8s.gcr.io/k8s-dns-sidecar-amd64:1.14.8
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/etcd-amd64:3.1.12 k8s.gcr.io/etcd-amd64:3.1.12
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/flannel:v0.10.0-amd64 quay.io/coreos/flannel:v0.10.0-amd64
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/pause-amd64:3.1 k8s.gcr.io/pause-amd64:3.1

可以將上面的命令保存為一個shell腳本，然后直接執行即可。這些鏡像是在master節點上需要使用到的鏡像，一定要提前下載下來。

其他Node，執行下面的命令：

docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/kube-proxy-amd64:v1.10.0
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/flannel:v0.10.0-amd64
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/pause-amd64:3.1
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/kubernetes-dashboard-amd64:v1.8.3
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/heapster-influxdb-amd64:v1.3.3
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/heapster-grafana-amd64:v4.4.3
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/heapster-amd64:v1.4.2

docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/flannel:v0.10.0-amd64 quay.io/coreos/flannel:v0.10.0-amd64
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/pause-amd64:3.1 k8s.gcr.io/pause-amd64:3.1
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/kube-proxy-amd64:v1.10.0 k8s.gcr.io/kube-proxy-amd64:v1.10.0

docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/kubernetes-dashboard-amd64:v1.8.3 k8s.gcr.io/kubernetes-dashboard-amd64:v1.8.3
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/heapster-influxdb-amd64:v1.3.3 k8s.gcr.io/heapster-influxdb-amd64:v1.3.3
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/heapster-grafana-amd64:v4.4.3 k8s.gcr.io/heapster-grafana-amd64:v4.4.3
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/heapster-amd64:v1.4.2 k8s.gcr.io/heapster-amd64:v1.4.2

上面的這些鏡像是在Node節點中需要用到的鏡像，在join節點之前也需要先下載到節點上面。

安裝 kubeadm、kubelet、kubectl

在確保docker安裝完成后，上面的相關環境配置也完成了，對應所需要的鏡像(如果可以科學上網可以跳過這一步)也下載完成了，現在我們就可以來安裝kubeadm了，我們這里是通過指定yum源的方式來進行安裝的：

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

當然了，上面的yum源也是需要科學上網的，如果不能科學上網的話，我們可以使用阿里雲的源進行安裝：

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
        http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

目前阿里雲的源最新版本已經是1.10版本，所以可以直接安裝。yum源配置完成后，執行安裝命令即可：

$ yum makecache fast && yum install -y kubelet kubeadm kubectl

正常情況我們可以都能順利安裝完成上面的文件。

配置 kubelet

安裝完成后，我們還需要對kubelet進行配置，因為用yum源的方式安裝的kubelet生成的配置文件將參數--cgroup-driver改成了systemd，而docker的cgroup-driver是cgroupfs，這二者必須一致才行，我們可以通過docker info命令查看：

$ docker info |grep Cgroup
Cgroup Driver: cgroupfs

修改文件kubelet的配置文件/etc/systemd/system/kubelet.service.d/10-kubeadm.conf，將其中的KUBELET_CGROUP_ARGS參數更改成cgroupfs：

Environment="KUBELET_CGROUP_ARGS=--cgroup-driver=cgroupfs"

另外還有一個問題是關於交換分區的，之前我們在手動搭建高可用的kubernetes 集群一文中已經提到過，Kubernetes從1.8開始要求關閉系統的 Swap ，如果不關閉，默認配置的kubelet將無法啟動，我們可以通過 kubelet 的啟動參數--fail-swap-on=false更改這個限制，所以我們需要在上面的配置文件中增加一項配置(在ExecStart之前)：

Environment="KUBELET_EXTRA_ARGS=--fail-swap-on=false"

當然最好的還是將swap給關掉，這樣能提高kubelet的性能。修改完成后，重新加載我們的配置文件即可：

$ systemctl daemon-reload

集群安裝

初始化

到這里我們的准備工作就完成了，接下來我們就可以在master節點上用kubeadm命令來初始化我們的集群了：

$ kubeadm init --kubernetes-version=v1.10.0 --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=192.168.11.1

命令非常簡單，就是kubeadm init，后面的參數是需要安裝的集群版本，因為我們這里選擇flannel作為 Pod 的網絡插件，所以需要指定–pod-network-cidr=10.244.0.0/16，然后是apiserver的通信地址，這里就是我們master節點的IP 地址。執行上面的命令，如果出現
running with swap on is not supported. Please disable swap之類的錯誤，則我們還需要增加一個參數–ignore-preflight-errors=Swap來忽略swap的錯誤提示信息：

$ kubeadm init \
   --kubernetes-version=v1.10.0 \
   --pod-network-cidr=10.244.0.0/16 \
   --apiserver-advertise-address=192.168.11.1 \
   --ignore-preflight-errors=Swap
[init] Using Kubernetes version: v1.10.0
[init] Using Authorization modes: [Node RBAC]
[preflight] Running pre-flight checks.
    [WARNING FileExisting-crictl]: crictl not found in system path
Suggestion: go get github.com/kubernetes-incubator/cri-tools/cmd/crictl
[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 [ydzs-master1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.151.30.57]
[certificates] Generated apiserver-kubelet-client certificate and key.
[certificates] Generated etcd/ca certificate and key.
[certificates] Generated etcd/server certificate and key.
[certificates] etcd/server serving cert is signed for DNS names [localhost] and IPs [127.0.0.1]
[certificates] Generated etcd/peer certificate and key.
[certificates] etcd/peer serving cert is signed for DNS names [ydzs-master1] and IPs [10.151.30.57]
[certificates] Generated etcd/healthcheck-client certificate and key.
[certificates] Generated apiserver-etcd-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: "/etc/kubernetes/admin.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/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 22.007661 seconds
[uploadconfig] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[markmaster] Will mark node ydzs-master1 as master by adding a label and a taint
[markmaster] Master ydzs-master1 tainted and labelled with key/value: node-role.kubernetes.io/master=""
[bootstraptoken] Using token: 8xomlq.0cdf2pbvjs2gjho3
[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 192.168.11.1:6443 --token 8xomlq.0cdf2pbvjs2gjho3 --discovery-token-ca-cert-hash sha256:92802317cb393682c1d1356c15e8b4ec8af2b8e5143ffd04d8be4eafb5fae368

上面的信息記錄了kubeadm初始化整個集群的過程，生成相關的各種證書、kubeconfig文件、bootstraptoken等等，后邊是使用kubeadm join往集群中添加節點時用到的命令，下面的命令是配置如何使用kubectl訪問集群的方式：

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

最后給出了將節點加入集群的命令：

kubeadm join 192.168.11.1:6443 --token 8xomlq.0cdf2pbvjs2gjho3 --discovery-token-ca-cert-hash sha256:92802317cb393682c1d1356c15e8b4ec8af2b8e5143ffd04d8be4eafb5fae368

我們根據上面的提示配置好kubectl后，就可以使用kubectl來查看集群的信息了：

$ kubectl get cs
NAME                 STATUS    MESSAGE              ERROR
scheduler            Healthy   ok
controller-manager   Healthy   ok
etcd-0               Healthy   {"health": "true"}
$ kubectl get csr
NAME                                                   AGE       REQUESTOR                 CONDITION
node-csr-8qygb8Hjxj-byhbRHawropk81LHNPqZCTePeWoZs3-g   1h        system:bootstrap:8xomlq   Approved,Issued
$ kubectl get nodes
NAME           STATUS    ROLES     AGE       VERSION
ydzs-master1   Ready     master    3h        v1.10.0

如果你的集群安裝過程中遇到了其他問題，我們可以使用下面的命令來進行重置：

$ kubeadm reset
$ ifconfig cni0 down && ip link delete cni0
$ ifconfig flannel.1 down && ip link delete flannel.1
$ rm -rf /var/lib/cni/

安裝 Pod Network

接下來我們來安裝flannel網絡插件，很簡單，和安裝普通的POD沒什么兩樣：

$ wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
$ kubectl apply -f  kube-flannel.yml
clusterrole.rbac.authorization.k8s.io "flannel" created
clusterrolebinding.rbac.authorization.k8s.io "flannel" created
serviceaccount "flannel" created
configmap "kube-flannel-cfg" created
daemonset.extensions "kube-flannel-ds" created

另外需要注意的是如果你的節點有多個網卡的話，需要在kube-flannel.yml中使用--iface參數指定集群主機內網網卡的名稱，否則可能會出現dns無法解析。flanneld啟動參數加上--iface=<iface-name>

args:
- --ip-masq
- --kube-subnet-mgr
- --iface=eth0

安裝完成后使用kubectl get pods命令可以查看到我們集群中的組件運行狀態，如果都是Running狀態的話，那么恭喜你，你的master節點安裝成功了。

$ kubectl get pods --all-namespaces
NAMESPACE     NAME                                   READY     STATUS    RESTARTS   AGE
kube-system   etcd-ydzs-master1                      1/1       Running   0          10m
kube-system   kube-apiserver-ydzs-master1            1/1       Running   0          10m
kube-system   kube-controller-manager-ydzs-master1   1/1       Running   0          10m
kube-system   kube-dns-86f4d74b45-f5595              3/3       Running   0          10m
kube-system   kube-flannel-ds-qxjs2                  1/1       Running   0          1m
kube-system   kube-proxy-vf5fg                       1/1       Running   0          10m
kube-system   kube-scheduler-ydzs-master1            1/1       Running   0          10m

kubeadm初始化完成后，默認情況下Pod是不會被調度到master節點上的，所以現在還不能直接測試普通的Pod，需要添加一個工作節點后才可以。

添加節點

同樣的上面的環境配置、docker 安裝、kubeadmin、kubelet、kubectl 這些都在Node(192.168.11.2)節點安裝配置好過后，我們就可以直接在 Node 節點上執行kubeadm join命令了（上面初始化的時候有），同樣加上參數--ignore-preflight-errors=Swap:

$ kubeadm join 192.168.11.1:6443 --token 8xomlq.0cdf2pbvjs2gjho3 --discovery-token-ca-cert-hash sha256:92802317cb393682c1d1356c15e8b4ec8af2b8e5143ffd04d8be4eafb5fae368 --ignore-preflight-errors=Swap
[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
Suggestion: go get github.com/kubernetes-incubator/cri-tools/cmd/crictl
[discovery] Trying to connect to API Server "10.151.30.57:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://192.168.11.1:6443"
[discovery] Requesting info from "https://10.151.30.57:6443" again to validate TLS against the pinned public key
[discovery] Cluster info signature and contents are valid and TLS certificate validates against pinned roots, will use API Server "10.151.30.57:6443"
[discovery] Successfully established connection with API Server "10.151.30.57:6443"

This node has joined the cluster:
* Certificate signing request was sent to master and a response
  was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the master to see this node join the cluster.

我們可以看到該節點已經加入到集群中去了，然后我們把master節點的~/.kube/config文件拷貝到當前節點對應的位置即可使用kubectl命令行工具了。

$ kubectl get nodes
NAME           STATUS    ROLES     AGE       VERSION
evjfaxic       Ready     <none>    1h        v1.10.0
ydzs-master1   Ready     master    3h        v1.10.0

創建個nginx pod測試一下
docker pull registry.cn-hangzhou.aliyuncs.com/qinyujia-test/nginx

apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
     app: nginx
spec:
     containers:
        - name: nginx
          image: registry.cn-hangzhou.aliyuncs.com/qinyujia-test/nginx
          imagePullPolicy: IfNotPresent
          ports:
          - containerPort: 80
     restartPolicy: Always
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  type: NodePort
  sessionAffinity: ClientIP
  selector:
    app: nginx
  ports:
    - port: 80
      nodePort: 30080

kubectl create -f hello.yaml