ubuntu16.04 kubeadm快速搭建kubernetes环境
刚开始百度到一些很复杂的教程，不太方便入门。
由于kebernetes的源放在google，所以，需要科学上网。
kubernetes的基础知识请自行找教程学习。
主要参考：
https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/
http://blog.csdn.net/ximenghappy/article/details/70157361
step1:安装相应软件
apt-get update
apt-get install -y curl apt-transport-https
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb http://apt.kubernetes.io/ kubernetes-xenial main
EOF
apt-get update
#如果没有安装docker的需要先安装docker，我用官网最新版本的docker遇到版本不匹配的情况，所以还是按照官方教程做比较好
apt-get install -y docker.io
apt-get install -y kubelet kubeadm kubectl kubernetes-cnistep2：使用kubeadm 初始化 kubernetes 集群
kubeadm init --pod-network-cidr=10.244.0.0/16这个时候，kubeadm会初始化各种环境配置，包括部署证书（private ca）和密钥，然后调用docker pull相应的镜像
以下是log输出
[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
[init] Using Kubernetes version: v1.6.6
[init] Using Authorization modes: [RBAC]
[preflight] Running pre-flight checks
[certificates] Generated CA certificate and key.
[certificates] Generated API server certificate and key.
[certificates] API Server serving cert is signed for DNS names [c-pc kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.217.135]
[certificates] Generated API server kubelet client certificate and key.
[certificates] Generated service account token signing 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"
[apiclient] Created API client, waiting for the control plane to become ready
[apiclient] All control plane components are healthy after 710.502147 seconds
[token] Using token: c64554.15b62d72ae89cbb3
[apiconfig] Created RBAC rules
[addons] Applied essential addon: kube-proxy
[addons] Applied essential addon: kube-dns
Your Kubernetes master has initialized successfully!
To start using your cluster, you need to run (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:
http://kubernetes.io/docs/admin/addons/
You can now join any number of machines by running the following on each node
as root:
kubeadm join --token c64554.15b62d72ae89cbb3 192.168.217.135:6443
提示：在log看到这句输出的时候，docker就开始pull对应的镜像，比较耗时，耗时取决于你的网速
[apiclient] Created API client, waiting for the control plane to become ready
pull完镜像后，可以看到
root@c-pc:~# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
gcr.io/google_containers/kube-proxy-amd64 v1.6.6 b01133efa4f0 2 weeks ago 109 MB
gcr.io/google_containers/kube-controller-manager-amd64 v1.6.6 a1b8bfeff845 2 weeks ago 132.9 MB
gcr.io/google_containers/kube-apiserver-amd64 v1.6.6 eaedf2552acd 2 weeks ago 150.7 MB
gcr.io/google_containers/kube-scheduler-amd64 v1.6.6 b662c4a72c62 2 weeks ago 76.75 MB
gcr.io/google_containers/etcd-amd64 3.0.17 243830dae7dd 4 months ago 168.9 MB
gcr.io/google_containers/pause-amd64 3.0 99e59f495ffa 14 months ago 746.9 kB
kubectl查看node和pod的状态
根据log提示，需要配置kubectl的配置，
初始化kubectl配置
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config需要先执行以上操作，否则会遇到以下错误提示
root@c-pc:~# kubectl get nodes
The connection to the server localhost:8080 was refused - did you specify the right host or port?
最新的kubectl链接api server不是通过8080端口连接的，而是通过6443端口，可以在admin.conf查看
...
server: https://192.168.217.135:6443
...初始化kubectl配置之后
root@c-pc:~# kubectl get nodes
The connection to the server localhost:8080 was refused - did you specify the right host or port?
root@c-pc:~# mkdir -p $HOME/.kube
root@c-pc:~# cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
root@c-pc:~# chown $(id -u):$(id -g) $HOME/.kube/config
root@c-pc:~# kubectl get nodes
NAME STATUS AGE VERSION
c-pc NotReady 3h v1.7.0
居然是NotReady状态！！
查看以下pods的状态，发现kube-dns 还在挂起，怪不得docker images的时候没有发现kube-dns镜像
root@c-pc:~# kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system etcd-c-pc 1/1 Running 0 3h
kube-system kube-apiserver-c-pc 1/1 Running 0 3h
kube-system kube-controller-manager-c-pc 1/1 Running 0 3h
kube-system kube-dns-2838158301-v0srq 0/3 Pending 0 3h
kube-system kube-proxy-ql2g0 1/1 Running 0 3h
kube-system kube-scheduler-c-pc 1/1 Running 0 3h
按照官网教程，需要配置pod的网络，这里使用了flannel网络，依次执行
kubectl create -f https://github.com/coreos/flannel/raw/master/Documentation/kube-flannel-rbac.yml
kubectl create -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml查看以下pods的状态
root@c-pc:~# kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system etcd-c-pc 1/1 Running 0 3h
kube-system kube-apiserver-c-pc 1/1 Running 0 3h
kube-system kube-controller-manager-c-pc 1/1 Running 0 3h
kube-system kube-dns-2838158301-v0srq 0/3 Pending 0 3h
kube-system kube-flannel-ds-vp7mt 0/2 ContainerCreating 0 12s
kube-system kube-proxy-ql2g0 1/1 Running 0 3h
kube-system kube-scheduler-c-pc 1/1 Running 0 3h
这个时候开始创建pull flannel的image了，稍等一下，
root@c-pc:~# kubectl get nodes
NAME STATUS AGE VERSION
c-pc Ready 3h v1.7.0
root@c-pc:~# kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system etcd-c-pc 1/1 Running 0 3h
kube-system kube-apiserver-c-pc 1/1 Running 0 3h
kube-system kube-controller-manager-c-pc 1/1 Running 0 3h
kube-system kube-dns-2838158301-v0srq 3/3 Running 0 3h
kube-system kube-flannel-ds-vp7mt 2/2 Running 0 6m
kube-system kube-proxy-ql2g0 1/1 Running 0 3h
kube-system kube-scheduler-c-pc 1/1 Running 0 3h
node的状态变成ready，good！
在另外一台机器上
kubeadm join –token c64554.15b62d72ae89cbb3 192.168.217.135:6443
在master主机上可以看到
root@c-pc:~# kubectl get nodes
NAME STATUS AGE VERSION
c-pc Ready 4h v1.7.0
c-pc2 Ready 27s v1.7.0