什么是kubernets
k8s是一个便携式、可扩展的开源平台，管理容器负载和服务，配置及自动化。提供了应用部署，规划，更新，维护的一种机制
安装docker
apt-get install -y docker.io
内核
内核必须支持 memory and swap accounting 。确认你的linux内核开启了如下配置
#cat /boot/config-***-generic
CONFIG_RESOURCE_COUNTERS=y
CONFIG_MEMCG=y
CONFIG_MEMCG_SWAP=y
CONFIG_MEMCG_SWAP_ENABLED=y
CONFIG_MEMCG_KMEM=y
以命令行参数方式,在内核启动时开启 memory and swap accounting 选项:
GRUB_CMDLINE_LINUX="cgroup_enable=memory swapaccount=1"
$vim /etc/default/grub
修改 GRUB_CMDLINE_LINUX=”” ==> GRUB_CMDLINE_LINUX=”cgroup_enable=memory”
保存后, 更新grub.cfg
update-grub
reboot
$cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-3.18.4-aufs root=/dev/sda5 ro cgroup_enable=memory swapaccount=1
用kubeadm安装k8s
本机环境：ubuntu LTS 1604
Linux master-node-01 4.4.0-116-generic #140-Ubuntu SMP Mon Feb 12 21:23:04 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
安装kubeadm
apt-get update && apt-get install -y 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
apt-get install -y kubelet kubeadm kubectl
#Configure cgroup driver used by kubelet on Master Node
sed -i "s/cgroup-driver=systemd/cgroup-driver=cgroupfs/g" /etc/systemd/system/kubelet.service.d/10-kubeadm.conf
初始化master
kubeadm init --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=192.168.12.9
在初始化输出后有提示
mkdir -p $HOME/.kube
cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
chown $(id -u):$(id -g) $HOME/.kube/config
当然如果是root用户还可以设置
export KUBECONFIG=/etc/kubernetes/admin.conf
net pod
继续看，还提示要为cluster部署一个网络pod
访问提示的网站，可以看到有很多供选择，如 Calico,Canal,Flannel,Kube-router,Romanna,Weave Net
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/v0.9.1/Documentation/kube-flannel.yml
若network已安装成功，可通过检查kube-dns pod是否正常运行
kubectl get pods --all-namespaces
kube-dns pod运行成功后，就可以继续加入nodes
join nodes
再住下看，还有提示加入cluster的信息
kubeadm join --token <token> <master-ip>:<master-port> --discovery-token-ca-cert-hash sha256:<hash>
workloads工作负载包含pods和containers等，nodes是工作负载运行的地方。在每个新node上执行以下步骤可将其加入集群
kubeadm join --token <token> <master-ip>:<master-port> --discovery-token-ca-cert-hash sha256:<hash>
安装完flannel节点后，node节点上的images镜像如下：
REPOSITORY TAG IMAGE ID CREATED SIZE
k8s.gcr.io/kube-proxy-amd64 v1.10.1 6e6237849607 10 days ago 97.1 MB
k8s.gcr.io/pause-amd64 3.1 da86e6ba6ca1 4 months ago 742 kB
quay.io/coreos/flannel v0.9.1-amd64 2b736d06ca4c 5 months ago 51.3 MB
kubeadm token
kubeadm token create --print-join-command #用这个命令可以查看kubeadm init输出加入cluster的信息
最后，在master上查看信息
[root@master1 ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
master1 Ready master 17m v1.10.1
node1 Ready <none> 17m v1.10.1
node2 Ready <none> 17m v1.10.1
[root@master1 ~]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
k8s.gcr.io/kube-proxy-amd64 v1.10.1 6e6237849607 10 days ago 97.1 MB
k8s.gcr.io/kube-apiserver-amd64 v1.10.1 9df3c00f55e6 10 days ago 225 MB
k8s.gcr.io/kube-scheduler-amd64 v1.10.1 ceecd7155649 10 days ago 50.4 MB
k8s.gcr.io/kube-controller-manager-amd64 v1.10.1 8401bb3ff261 10 days ago 148 MB
k8s.gcr.io/etcd-amd64 3.1.12 52920ad46f5b 6 weeks ago 193 MB
k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64 1.14.8 c2ce1ffb51ed 3 months ago 40.9 MB
k8s.gcr.io/k8s-dns-sidecar-amd64 1.14.8 6f7f2dc7fab5 3 months ago 42.2 MB
k8s.gcr.io/k8s-dns-kube-dns-amd64 1.14.8 80cc5ea4b547 3 months ago 50.5 MB
k8s.gcr.io/pause-amd64 3.1 da86e6ba6ca1 4 months ago 742 kB
k8s.gcr.io/kubernetes-dashboard-amd64 v1.8.1 e94d2f21bc0c 4 months ago 121 MB
quay.io/coreos/flannel v0.9.1-amd64 2b736d06ca4c 5 months ago 51.3 MB
[root@master1 ~]# kubectl get pods --all-namespaces -o wide
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE
kube-system etcd-master1 1/1 Running 0 36m 192.16.35.12 master1
kube-system kube-apiserver-master1 1/1 Running 0 36m 192.16.35.12 master1
kube-system kube-controller-manager-master1 1/1 Running 0 36m 192.16.35.12 master1
kube-system kube-dns-86f4d74b45-j6mqc 3/3 Running 0 36m 10.244.0.7 master1
kube-system kube-flannel-ds-clsww 1/1 Running 0 36m 192.16.35.12 master1
kube-system kube-flannel-ds-gh8rs 1/1 Running 4 36m 192.16.35.10 node1
kube-system kube-flannel-ds-tdhtz 1/1 Running 0 36m 192.16.35.11 node2
kube-system kube-proxy-4nzzc 1/1 Running 0 36m 192.16.35.11 node2
kube-system kube-proxy-lgfrk 1/1 Running 0 36m 192.16.35.12 master1
kube-system kube-proxy-mjjgk 1/1 Running 0 36m 192.16.35.10 node1
kube-system kube-scheduler-master1 1/1 Running 0 36m 192.16.35.12 master1
kube-system kubernetes-dashboard-8469446955-jsj6m 0/1 CrashLoopBackOff 11 36m 10.244.0.6 master1
利用ansible部署基于kubeadm的k8s
https://github.com/kaizamm/kubeadm-ansible.git
Dashboard
kubectl proxy --address="192.168.12.9" -p 8001 --accept-hosts='^*$'
troubleshooting
- Q: kubelet无法启动
-
A: 通过journalctl -xeu kubelet查看提示信息，注意思如下三点：1.cgroupsfs的修改 2.kubeadm 的执行结果（master:kubeadm join; nodes: kubeadm join）
- Q: ‘kubectl get nodes’查看到的信息只有一个master提示ready，其余notready
- A: 查看nodes的flannel网络是否正常，查看image是否已全部下载完毕