Ubuntu20.4 上搭建microk8s集群

准备三台Ubuntu20.04服务器

1、在服务器上安装snapd

sudo apt insall snapd -y

安装完成后用snap version 查看版本。

snap version
snap    2.57.1
snapd   2.57.1
series  16
ubuntu  20.04
kernel  5.4.0-121-generic

 2、安装microk8s

sudo snap install microk8s --classic --channel=1.25

 加channel可以指定版本安装，不加默认安装最新版本。

设置kubectl别名

sudo snap alias microk8s.kubectl kubectl

在国内由于众所周知的原因，安装microk8s后会发现 gcr.io的docker image无法下载的问题.(详细安装步骤参见 MicroK8s - Zero-ops Kubernetes for developers, edge and IoT)，首先需要安装 pullk8s 工具，此工具可以通过 hub.docker.com 的 opsdockerimage 仓库下载k8s所需的 k8s.gcr.io 或 gcr.io 镜像，每天更新一次，包括所有image 的全平台的所有tags。

 git clone https://github.com/OpsDocker/pullk8s.git
 cd pullk8s
 sudo cp pullk8s.sh /usr/local/bin/pullk8s
 sudo chmod +x /usr/local/bin/pullk8s

pullk8s这个工具依赖docker 来拉镜像，需要安装好docker

sudo snap install docker

安装完后可以用pullk8s检查所缺的镜像

 sudo pullk8s check --microk8s
 k8s.gcr.io/pause:3.1

使用 pullk8s 拉取失败的镜像，并导入到 pod 空间中

sudo pullk8s pull k8s.gcr.io/pause:3.1 --microk8s

编辑文件/var/snap/microk8s/current/args/containerd-template.toml替换sandbox_image为国内镜像源。

stream_server_address = "127.0.0.1"
 28   stream_server_port = "0"
 29   enable_selinux = false
 30   sandbox_image = "registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.1"
 31   stats_collect_period = 10

启动dns组件

sudo microk8s enable dns

这样microk8s就安装好了。

3、在另外两台服务器上重复上述步骤分别部署microk8s

选择一台机器作为主节点，在主节点机器上配置host

masterip master
node1ip  node1
node2ip  node2

在主节点上运行add-node命名

sudo microk8s add-node

From the node you wish to join to this cluster, run the following:
microk8s join 192.168.1.230:25000/92b2db237428470dc4fcfc4ebbd9dc81/2c0cb3284b05

Use the '--worker' flag to join a node as a worker not running the control plane, eg:
microk8s join 192.168.1.230:25000/92b2db237428470dc4fcfc4ebbd9dc81/2c0cb3284b05 --worker

If the node you are adding is not reachable through the default interface you can use one of the following:
microk8s join 192.168.1.230:25000/92b2db237428470dc4fcfc4ebbd9dc81/2c0cb3284b05
microk8s join 10.23.209.1:25000/92b2db237428470dc4fcfc4ebbd9dc81/2c0cb3284b05
microk8s join 172.17.0.1:25000/92b2db237428470dc4fcfc4ebbd9dc81/2c0cb3284b05

 分别在另外两个字节点上运行刚返回的指令

microk8s join 192.168.1.230:25000/92b2db237428470dc4fcfc4ebbd9dc81/2c0cb3284b05

Contacting cluster at 192.168.1.230

The node has joined the cluster and will appear in the nodes list in a few seconds.

Currently this worker node is configured with the following kubernetes API server endpoints:
    - 192.168.1.230 and port 16443, this is the cluster node contacted during the join operation.

If the above endpoints are incorrect, incomplete or if the API servers are behind a loadbalancer please update
/var/snap/microk8s/current/args/traefik/provider.yaml

将一个节点加入集群应该只需要几秒钟。之后应该能够看到节点已加入

kubectl get nodes
NAME    STATUS     ROLES    AGE   VERSION
master  Ready         43m   v1.24.0-2+59bbb3530b6769
node1   Ready         89s   v1.24.0-2+59bbb3530b6769
node2   Ready         34m   v1.24.0-2+59bbb3530b6769