用kubeadm在Ubuntu上快速构建Kubernetes测试集群
本文将介绍如何在Ubuntu server 16.04版本上安装kubeadm，并利用kubeadm快速的在Ubuntu server 版本 16.04上构建一个kubernetes的基础的测试集群，用来做学习和测试用途，当前（2018-04-14）最新的版本是1.10.1。参考文档包括kubernetes官方网站的kubeadm安装文档以及利用kubeadm创建集群这两个文档。
生产用途的环境，需要考虑各个组件的高可用，建议参考Kubernetes的官方的相关的安装文档。
概述
本次安装建议至少4台服务器或者虚拟机，每台服务器4G内存，2个CPU核心以上，基本架构为1台master节点，3台slave节点。整个安装过程将在Ubuntu服务器上安装完kubeadm，以及安装kubernetes的基本集群，包括canal网络，另后台存储可参考本书的最佳实践中的存储管理内容。 本次安装一共4个节点，节点信息如下:
| 角色 | 主机名 | IP地址 |
|---|---|---|
| Master | Ubuntu-master | 192.168.5.200 |
| Slave | ubuntu-1 | 192.168.5.201 |
| Slave | ubuntu-2 | 192.168.5.202 |
| Slave | ubuntu-3 | 192.168.5.203 |
准备工作
- 默认方式安装Ubuntu Server 版本 16.04
- 配置主机名映射，每个节点
# cat /etc/hosts
127.0.0.1 localhost
192.168.0.200 Ubuntu-master
192.168.0.201 Ubuntu-1
192.168.0.202 Ubuntu-2
192.168.0.203 Ubuntu-3
- 如果连接gcr网站不方便，无法下载镜像，会导致安装过程卡住，可以下载我导出的镜像包，我导出的镜像网盘链接，解压缩以后是多个个tar包，使用
docker load< xxxx.tar导入各个文件即可）。在所有节点上安装kubeadm
查看apt安装源如下配置，使用阿里云的系统和kubernetes的源。
$ cat /etc/apt/sources.list
# 系统安装源
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted
deb http://mirrors.aliyun.com/ubuntu/ xenial universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe
deb http://mirrors.aliyun.com/ubuntu/ xenial multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
# kubeadm及kubernetes组件安装源
deb https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial main
安装docker，可以使用系统源的的docker.io软件包，版本1.13.1，我的系统里是已经安装好最新的版本了。
# apt-get install docker.io
Reading package lists... Done
Building dependency tree
Reading state information... Done
docker.io is already the newest version (1.13.1-0ubuntu1~16.04.2).
0 upgraded, 0 newly installed, 0 to remove and 4 not upgraded.
更新源，可以不理会gpg的报错信息。
# apt-get update
Hit:1 http://mirrors.aliyun.com/ubuntu xenial InRelease
Hit:2 http://mirrors.aliyun.com/ubuntu xenial-updates InRelease
Hit:3 http://mirrors.aliyun.com/ubuntu xenial-backports InRelease
Get:4 https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial InRelease [8,993 B]
Ign:4 https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial InRelease
Fetched 8,993 B in 0s (20.7 kB/s)
Reading package lists... Done
W: GPG error: https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6A030B21BA07F4FB
W: The repository 'https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
强制安装kubeadm，kubectl，kubelet软件包。
# apt-get install -y kubelet kubeadm kubectl --allow-unauthenticated
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
kubernetes-cni socat
The following NEW packages will be installed:
kubeadm kubectl kubelet kubernetes-cni socat
0 upgraded, 5 newly installed, 0 to remove and 4 not upgraded.
Need to get 56.9 MB of archives.
After this operation, 410 MB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
kubernetes-cni kubelet kubectl kubeadm
Authentication warning overridden.
Get:1 http://mirrors.aliyun.com/ubuntu xenial/universe amd64 socat amd64 1.7.3.1-1 [321 kB]
Get:2 https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial/main amd64 kubernetes-cni amd64 0.6.0-00 [5,910 kB]
Get:3 https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial/main amd64 kubelet amd64 1.10.1-00 [21.1 MB]
Get:4 https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial/main amd64 kubectl amd64 1.10.1-00 [8,906 kB]
Get:5 https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial/main amd64 kubeadm amd64 1.10.1-00 [20.7 MB]
Fetched 56.9 MB in 5s (11.0 MB/s)
Use of uninitialized value $_ in lc at /usr/share/perl5/Debconf/Template.pm line 287.
Selecting previously unselected package kubernetes-cni.
(Reading database ... 191799 files and directories currently installed.)
Preparing to unpack .../kubernetes-cni_0.6.0-00_amd64.deb ...
Unpacking kubernetes-cni (0.6.0-00) ...
Selecting previously unselected package socat.
Preparing to unpack .../socat_1.7.3.1-1_amd64.deb ...
Unpacking ....
....
kubeadm安装完以后，就可以使用它来快速安装部署Kubernetes集群了。
使用kubeadm安装Kubernetes集群
使用kubeadmin初始化master节点
因为使用要使用canal，因此需要在初始化时加上网络配置参数,设置kubernetes的子网为10.244.0.0/16，注意此处不要修改为其他地址，因为这个值与后续的canal的yaml值要一致，如果修改，请一并修改。
这个下载镜像的过程涉及翻墙，因为会从gcr的站点下载容器镜像。。。（如果大家翻墙不方便的话，可以用我在上文准备工作中提到的导出的镜像）。
如果有能够连接gcr站点的网络，那么整个安装过程非常简单。
# kubeadm init --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=192.168.0.200
[init] Using Kubernetes version: v1.10.1
[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 [ubuntu-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.0.200]
[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 [ubuntu-master] and IPs [192.168.0.200]
[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 28.003828 seconds
[uploadconfig] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[markmaster] Will mark node ubuntu-master as master by adding a label and a taint
[markmaster] Master ubuntu-master tainted and labelled with key/value: node-role.kubernetes.io/master=""
[bootstraptoken] Using token: rw4enn.mvk547juq7qi2b5f
[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 192.168.0.200:6443 --token rw4enn.mvk547juq7qi2b5f --discovery-token-ca-cert-hash sha256:ba260d5191213382a806a9a7d92c9e6bb09061847c7914b1ac584d0c69471579
执行如下命令来配置kubectl。
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
这样master的节点就配置好了，并且可以使用kubectl来进行各种操作了，根据上面的提示接着往下做，将slave节点加入到集群。
Slave节点加入集群
在slave节点执行如下的命令,将slave节点加入集群，正常的返回信息如下：
#kubeadm join 192.168.0.200:6443 --token rw4enn.mvk547juq7qi2b5f --discovery-token-ca-cert-hash sha256:ba260d5191213382a806a9a7d92c9e6bb09061847c7914b1ac584d0c69471579
[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
[discovery] Trying to connect to API Server "192.168.0.200:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://192.168.0.200:6443"
[discovery] Requesting info from "https://192.168.0.200:6443" 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 "192.168.0.200:6443"
[discovery] Successfully established connection with API Server "192.168.0.200:6443"
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.
等待节点加入完毕。加入中状态。
# kubectl get node
NAME STATUS ROLES AGE VERSION
ubuntu-1 NotReady <none> 6m v1.10.1
ubuntu-2 NotReady <none> 6m v1.10.1
ubuntu-3 NotReady <none> 6m v1.10.1
ubuntu-master NotReady master 10m v1.10.1
在master节点查看信息如下状态为节点加入完毕。
root@Ubuntu-master:~# kubectl get pod -n kube-system -o wide
NAME READY STATUS RESTARTS AGE IP NODE
etcd-ubuntu-master 1/1 Running 0 21m 192.168.0.200 ubuntu-master
kube-apiserver-ubuntu-master 1/1 Running 0 21m 192.168.0.200 ubuntu-master
kube-controller-manager-ubuntu-master 1/1 Running 0 22m 192.168.0.200 ubuntu-master
kube-dns-86f4d74b45-wkfk2 0/3 Pending 0 22m <none> <none>
kube-proxy-6ddb4 1/1 Running 0 22m 192.168.0.200 ubuntu-master
kube-proxy-7ngb9 1/1 Running 0 17m 192.168.0.202 ubuntu-2
kube-proxy-fkhhx 1/1 Running 0 18m 192.168.0.201 ubuntu-1
kube-proxy-rh4lq 1/1 Running 0 18m 192.168.0.203 ubuntu-3
kube-scheduler-ubuntu-master 1/1 Running 0 21m 192.168.0.200 ubuntu-master
kubedns组件需要在网络插件完成安装以后会自动安装完成。
安装网络插件canal
从canal官方文档参考，如下网址下载2个文件并且安装，其中一个是配置canal的RBAC权限，一个是部署canal的DaemonSet。
# kubectl apply -f https://docs.projectcalico.org/v3.0/getting-started/kubernetes/installation/hosted/canal/rbac.yaml
clusterrole.rbac.authorization.k8s.io "calico" created
clusterrole.rbac.authorization.k8s.io "flannel" created
clusterrolebinding.rbac.authorization.k8s.io "canal-flannel" created
clusterrolebinding.rbac.authorization.k8s.io "canal-calico" created
# kubectl apply -f https://docs.projectcalico.org/v3.0/getting-started/kubernetes/installation/hosted/canal/canal.yaml
configmap "canal-config" created
daemonset.extensions "canal" created
customresourcedefinition.apiextensions.k8s.io "felixconfigurations.crd.projectcalico.org" created
customresourcedefinition.apiextensions.k8s.io "bgpconfigurations.crd.projectcalico.org" created
customresourcedefinition.apiextensions.k8s.io "ippools.crd.projectcalico.org" created
customresourcedefinition.apiextensions.k8s.io "clusterinformations.crd.projectcalico.org" created
customresourcedefinition.apiextensions.k8s.io "globalnetworkpolicies.crd.projectcalico.org" created
customresourcedefinition.apiextensions.k8s.io "networkpolicies.crd.projectcalico.org" created
serviceaccount "canal" created
查看canal的安装状态。
# kubectl get pod -n kube-system -o wide
NAME READY STATUS RESTARTS AGE IP NODE
canal-fc94k 3/3 Running 10 4m 192.168.0.201 ubuntu-1
canal-rs2wp 3/3 Running 10 4m 192.168.0.200 ubuntu-master
canal-tqd4l 3/3 Running 10 4m 192.168.0.202 ubuntu-2
canal-vmpnr 3/3 Running 10 4m 192.168.0.203 ubuntu-3
etcd-ubuntu-master 1/1 Running 0 28m 192.168.0.200 ubuntu-master
kube-apiserver-ubuntu-master 1/1 Running 0 28m 192.168.0.200 ubuntu-master
kube-controller-manager-ubuntu-master 1/1 Running 0 29m 192.168.0.200 ubuntu-master
kube-dns-86f4d74b45-wkfk2 3/3 Running 0 28m 10.244.2.2 ubuntu-3
kube-proxy-6ddb4 1/1 Running 0 28m 192.168.0.200 ubuntu-master
kube-proxy-7ngb9 1/1 Running 0 24m 192.168.0.202 ubuntu-2
kube-proxy-fkhhx 1/1 Running 0 24m 192.168.0.201 ubuntu-1
kube-proxy-rh4lq 1/1 Running 0 24m 192.168.0.203 ubuntu-3
kube-scheduler-ubuntu-master 1/1 Running 0 28m 192.168.0.200 ubuntu-master
可以看到canal和kube-dns都已经运行正常，一个基本功能正常的测试环境就部署完毕了。
此时查看集群的节点状态，版本为最新的版本v1.10.1。
# kubectl get node
NAME STATUS ROLES AGE VERSION
ubuntu-1 Ready <none> 27m v1.10.1
ubuntu-2 Ready <none> 27m v1.10.1
ubuntu-3 Ready <none> 27m v1.10.1
ubuntu-master Ready master 31m v1.10.1
让master也运行pod（默认master不运行pod）,这样在测试环境做是可以的，不建议在生产环境如此操作。
#kubectl taint nodes --all node-role.kubernetes.io/master-
node "ubuntu-master" untainted
taint "node-role.kubernetes.io/master:" not found
taint "node-role.kubernetes.io/master:" not found
taint "node-role.kubernetes.io/master:" not found
后续如果想要集群其他功能启用，请参考后续文章。