kubeadm
是 Kubernetes
官方提供的用于快速安装 Kubernetes 集群的工具,通过将集群的各个组件进行容器化安装管理,通过 kubeadm
的方式安装集群比二进制的方式安装要方便不少,但是目录 kubeadm
还处于 beta
状态,还不能用于生产环境, Using kubeadm to Create a Cluster 文档中已经说明 kubeadm
将会很快能够用于生产环境了。
所以现在来了解下 kubeadm
的使用方式的话还是很有必要的,对于现阶段想要用于生产环境的,建议还是参考我们前面的文章: 手动搭建高可用的kubernetes 集群 或者 视频教程 。
我们这里准备两台 Centos7
的主机用于安装,后续节点可以根究需要添加即可:
$ cat /etc/hosts 10.151.30.57 ydzs-master1 10.151.30.62 evjfaxic
禁用防火墙:
$ systemctl stop firewalld $ systemctl disable firewalld
禁用SELINUX:
$ setenforce 0 $ cat /etc/selinux/config SELINUX=disabled
创建 /etc/sysctl.d/k8s.conf
文件,添加如下内容:
net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 net.ipv4.ip_forward = 1
执行如下命令使修改生效:
$ modprobe br_netfilter $ sysctl -p /etc/sysctl.d/k8s.conf
如果你的节点上面有科学上网的工具,可以忽略这一步,我们需要提前将所需的 gcr.io
上面的镜像下载到节点上面,当然前提条件是你已经成功安装了 docker
。
master
节点,执行下面的命令:
docker pull cnych/kube-apiserver-amd64:v1.10.0 docker pull cnych/kube-scheduler-amd64:v1.10.0 docker pull cnych/kube-controller-manager-amd64:v1.10.0 docker pull cnych/kube-proxy-amd64:v1.10.0 docker pull cnych/k8s-dns-kube-dns-amd64:1.14.8 docker pull cnych/k8s-dns-dnsmasq-nanny-amd64:1.14.8 docker pull cnych/k8s-dns-sidecar-amd64:1.14.8 docker pull cnych/etcd-amd64:3.1.12 docker pull cnych/flannel:v0.10.0-amd64 docker pull cnych/pause-amd64:3.1 docker tag cnych/kube-apiserver-amd64:v1.10.0 k8s.gcr.io/kube-apiserver-amd64:v1.10.0 docker tag cnych/kube-scheduler-amd64:v1.10.0 k8s.gcr.io/kube-scheduler-amd64:v1.10.0 docker tag cnych/kube-controller-manager-amd64:v1.10.0 k8s.gcr.io/kube-controller-manager-amd64:v1.10.0 docker tag cnych/kube-proxy-amd64:v1.10.0 k8s.gcr.io/kube-proxy-amd64:v1.10.0 docker tag cnych/k8s-dns-kube-dns-amd64:1.14.8 k8s.gcr.io/k8s-dns-kube-dns-amd64:1.14.8 docker tag cnych/k8s-dns-dnsmasq-nanny-amd64:1.14.8 k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64:1.14.8 docker tag cnych/k8s-dns-sidecar-amd64:1.14.8 k8s.gcr.io/k8s-dns-sidecar-amd64:1.14.8 docker tag cnych/etcd-amd64:3.1.12 k8s.gcr.io/etcd-amd64:3.1.12 docker tag cnych/flannel:v0.10.0-amd64 quay.io/coreos/flannel:v0.10.0-amd64 docker tag cnych/pause-amd64:3.1 k8s.gcr.io/pause-amd64:3.1
可以将上面的命令保存为一个 shell
脚本,然后直接执行即可。这些镜像是在 master
节点上需要使用到的镜像,一定要提前下载下来。
其他 Node
,执行下面的命令:
docker pull cnych/kube-proxy-amd64:v1.10.0 docker pull cnych/flannel:v0.10.0-amd64 docker pull cnych/pause-amd64:3.1 docker pull cnych/kubernetes-dashboard-amd64:v1.8.3 docker pull cnych/heapster-influxdb-amd64:v1.3.3 docker pull cnych/heapster-grafana-amd64:v4.4.3 docker pull cnych/heapster-amd64:v1.4.2 docker tag cnych/flannel:v0.10.0-amd64 quay.io/coreos/flannel:v0.10.0-amd64 docker tag cnych/pause-amd64:3.1 k8s.gcr.io/pause-amd64:3.1 docker tag cnych/kube-proxy-amd64:v1.10.0 k8s.gcr.io/kube-proxy-amd64:v1.10.0 docker tag cnych/kubernetes-dashboard-amd64:v1.8.3 k8s.gcr.io/kubernetes-dashboard-amd64:v1.8.3 docker tag cnych/heapster-influxdb-amd64:v1.3.3 k8s.gcr.io/heapster-influxdb-amd64:v1.3.3 docker tag cnych/heapster-grafana-amd64:v4.4.3 k8s.gcr.io/heapster-grafana-amd64:v4.4.3 docker tag cnych/heapster-amd64:v1.4.2 k8s.gcr.io/heapster-amd64:v1.4.2
上面的这些镜像是在 Node
节点中需要用到的镜像,在 join
节点之前也需要先下载到节点上面。
在确保 docker
安装完成后,上面的相关环境配置也完成了,对应所需要的镜像(如果可以科学上网可以跳过这一步)也下载完成了,现在我们就可以来安装 kubeadm
了,我们这里是通过指定 yum
源的方式来进行安装的:
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
当然了,上面的 yum
源也是需要科学上网的,如果不能科学上网的话,我们可以使用阿里云的源进行安装:
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
目前阿里云的源最新版本已经是1.10版本,所以可以直接安装。 yum
源配置完成后,执行安装命令即可:
$ yum makecache fast && yum install -y kubelet kubeadm kubectl
正常情况我们可以都能顺利安装完成上面的文件。
安装完成后,我们还需要对 kubelet
进行配置,因为用 yum
源的方式安装的 kubelet
生成的配置文件将参数 --cgroup-driver
改成了 systemd
,而 docker
的 cgroup-driver
是 cgroupfs
,这二者必须一致才行,我们可以通过 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
,将其中的 KUBELET_CGROUP_ARGS
参数更改成 cgroupfs
:
Environment="KUBELET_CGROUP_ARGS=--cgroup-driver=cgroupfs"
另外还有一个问题是关于交换分区的,之前我们在 手动搭建高可用的kubernetes 集群 一文中已经提到过, Kubernetes
从1.8开始要求关闭系统的 Swap ,如果不关闭,默认配置的 kubelet
将无法启动,我们可以通过 kubelet 的启动参数 --fail-swap-on=false
更改这个限制,所以我们需要在上面的配置文件中增加一项配置(在 ExecStart
之前):
Environment="KUBELET_EXTRA_ARGS=--fail-swap-on=false"
当然最好的还是将 swap
给关掉,这样能提高 kubelet
的性能。修改完成后,重新加载我们的配置文件即可:
$ systemctl daemon-reload
到这里我们的准备工作就完成了,接下来我们就可以在 master
节点上用 kubeadm
命令来初始化我们的集群了:
$ kubeadm init --kubernetes-version=v1.10.0 --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=10.151.30.57
命令非常简单,就是 kubeadm init
,后面的参数是需要安装的集群版本,因为我们这里选择 flannel
作为 Pod 的网络插件,所以需要指定 –pod-network-cidr=10.244.0.0/16
,然后是 apiserver
的通信地址,这里就是我们 master
节点的IP 地址。执行上面的命令,如果出现 running with swap on is not supported. Please disable swap
之类的错误,则我们还需要增加一个参数 –ignore-preflight-errors=Swap
来忽略 swap
的错误提示信息:
$ kubeadm init / --kubernetes-version=v1.10.0 / --pod-network-cidr=10.244.0.0/16 / --apiserver-advertise-address=10.151.30.57 / --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 10.151.30.57:6443 --token 8xomlq.0cdf2pbvjs2gjho3 --discovery-token-ca-cert-hash sha256:92802317cb393682c1d1356c15e8b4ec8af2b8e5143ffd04d8be4eafb5fae368
上面的信息记录了 kubeadm
初始化整个集群的过程,生成相关的各种证书、 kubeconfig
文件、 bootstraptoken
等等,后边是使用 kubeadm join
往集群中添加节点时用到的命令,下面的命令是配置如何使用 kubectl
访问集群的方式: mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config 最后给出了将节点加入集群的命令:
kubeadm join 10.151.30.57:6443 --token 8xomlq.0cdf2pbvjs2gjho3 --discovery-token-ca-cert-hash sha256:92802317cb393682c1d1356c15e8b4ec8af2b8e5143ffd04d8be4eafb5fae368
我们根据上面的提示配置好 kubectl
后,就可以使用 kubectl
来查看集群的信息了:
$ 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
如果你的集群安装过程中遇到了其他问题,我们可以使用下面的命令来进行重置:
$ kubeadm reset $ ifconfig cni0 down && ip link delete cni0 $ ifconfig flannel.1 down && ip link delete flannel.1 $ rm -rf /var/lib/cni/
接下来我们来安装 flannel
网络插件,很简单,和安装普通的 POD
没什么两样:
$ 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节点有多个网卡的话,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。 flanneld
启动参数加上 --iface=<iface-name>
args: - --ip-masq - --kube-subnet-mgr - --iface=eth0
安装完成后使用 kubectl get pods
命令可以查看到我们集群中的组件运行状态,如果都是 Running
状态的话,那么恭喜你,你的 master
节点安装成功了。
$ 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,默认情况下 Pod
是不会被调度到 master
节点上的,所以现在还不能直接测试普通的 Pod
,需要添加一个工作节点后才可以。
同样的上面的环境配置、docker 安装、kubeadmin、kubelet、kubectl 这些都在Node(10.151.30.62)节点安装配置好过后,我们就可以直接在 Node 节点上执行 kubeadm join
命令了(上面初始化的时候有),同样加上参数 --ignore-preflight-errors=Swap
:
$ kubeadm join 10.151.30.57:6443 --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://10.151.30.57:6443" [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.
我们可以看到该节点已经加入到集群中去了,然后我们把 master
节点的 ~/.kube/config
文件拷贝到当前节点对应的位置即可使用 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
到这里就算我们的集群部署成功了,接下来就可以根据我们的需要安装一些附加的插件,比如 Dashboard、Heapster、Ingress-Controller等等,这些插件的安装方法就和我们之前手动安装集群的方式方法一样了,这里就不在重复了,有问题可以在下面留言讨论。
下面是 基于1.9版本手动搭建高可用Kubernetes集群的视频教程 ,对视频感兴趣的同学可以观看视频:
扫描下面的二维码(或微信搜索 k8s技术圈
)关注我们的微信公众帐号,在微信公众帐号中回复 加群 即可加入到我们的 kubernetes 讨论群里面共同学习。