k3s学习笔记

Kubernetes

字数统计: 1.2k阅读时长: 6 min

 2022/11/09   Share

前言

原生的k8s 组件太重了，如果放置在一些需要服务但是流量又少的地区，那k8s组件占用资源比业务都要多;

朋友给推荐了k3s，正好研究学习一下;

架构

单节点

此配置为最简单的基础配置, 只需要安装server(内置了agent)即可部署一个开箱即用的k8s环境, 也是最省成本的一种方式.

单Server节点和多agent

此种模式实际上是第一种的衍生的方式, 只是新加了 agent(work)。

多server和外部数据库结构

此种工作模式将数据抽离出来，从而达到server无状态并且高可用的一种情况。

使用内置的etcd数据库

此种工作模式不需要配置额外的数据库, 操作也比较简单，但是因为使用了etcd，所以节点必须要>3,且奇数。

控制器

Manifest Controller

类似于k8s的静态pod, 默认在 server的/var/lib/rancher/k3s/server/manifests 配置目录。

默认启用的:

Coredns
Metrics server
Local storage provisoner
Traefik Ingress controller

├── ccm.yaml
├── coredns.yaml
├── local-storage.yaml
├── metrics-server
│   ├── aggregated-metrics-reader.yaml
│   ├── auth-delegator.yaml
│   ├── auth-reader.yaml
│   ├── metrics-apiservice.yaml
│   ├── metrics-server-deployment.yaml
│   ├── metrics-server-service.yaml
│   └── resource-reader.yaml
├── rolebindings.yaml
└── traefik.yaml

默认组件

1	kubectl -n kube-system get helmcharts.helm.cattle.io

Helm Controller

可以直接使用helm，不需要安装helm。

Service Load Balancer

实际上用到了 Traefik, 做了ingress。

安装

下载github二进制文件, 这里.

安装server

简单部署

# 下载特定版本
wget https://github.com/k3s-io/k3s/releases/download/v1.22.15%2Bk3s1/k3s
chmod +x k3s


./k3s kubectl get all -A
NAMESPACE     NAME                                          READY   STATUS      RESTARTS   AGE
kube-system   pod/local-path-provisioner-84bb864455-5lvtb   1/1     Running     0          3m5s
kube-system   pod/coredns-7796b77cd4-7m8r2                  1/1     Running     0          3m5s
kube-system   pod/helm-install-traefik-crd-dl9nq            0/1     Completed   0          3m5s
kube-system   pod/metrics-server-ff9dbcb6c-vjk4w            1/1     Running     0          3m5s
kube-system   pod/helm-install-traefik-k7clb                0/1     Completed   2          3m5s
kube-system   pod/svclb-traefik-wq752                       2/2     Running     0          2m7s
kube-system   pod/traefik-d497b4cb6-wdpkd                   1/1     Running     0          2m7s

NAMESPACE     NAME                     TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)                      AGE
default       service/kubernetes       ClusterIP      10.43.0.1       <none>          443/TCP                      3m19s
kube-system   service/kube-dns         ClusterIP      10.43.0.10      <none>          53/UDP,53/TCP,9153/TCP       3m17s
kube-system   service/metrics-server   ClusterIP      10.43.16.176    <none>          443/TCP                      3m16s
kube-system   service/traefik          LoadBalancer   10.43.221.244   172.20.67.209   80:31377/TCP,443:30924/TCP   2m7s

NAMESPACE     NAME                           DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
kube-system   daemonset.apps/svclb-traefik   1         1         1       1            1           <none>          2m7s

NAMESPACE     NAME                                     READY   UP-TO-DATE   AVAILABLE   AGE
kube-system   deployment.apps/local-path-provisioner   1/1     1            1           3m17s
kube-system   deployment.apps/coredns                  1/1     1            1           3m17s
kube-system   deployment.apps/metrics-server           1/1     1            1           3m16s
kube-system   deployment.apps/traefik                  1/1     1            1           2m7s

NAMESPACE     NAME                                                DESIRED   CURRENT   READY   AGE
kube-system   replicaset.apps/local-path-provisioner-84bb864455   1         1         1       3m5s
kube-system   replicaset.apps/coredns-7796b77cd4                  1         1         1       3m5s
kube-system   replicaset.apps/metrics-server-ff9dbcb6c            1         1         1       3m5s
kube-system   replicaset.apps/traefik-d497b4cb6                   1         1         1       2m7s

NAMESPACE     NAME                                 COMPLETIONS   DURATION   AGE
kube-system   job.batch/helm-install-traefik-crd   1/1           44s        3m14s
kube-system   job.batch/helm-install-traefik       1/1           61s        3m14s

手动下载二进制安装

# 下载特定版本
wget https://github.com/k3s-io/k3s/releases/download/v1.22.15%2Bk3s1/k3s
chmod +x k3s
mv k3s /usr/local/bin/

# 安装
curl -sfL https://get.k3s.io | INSTALL_K3S_SKIP_DOWNLOAD="true"  sh - 

kubectl  get node
NAME           STATUS   ROLES                  AGE   VERSION
k3s-test-001   Ready    control-plane,master   20m   v1.22.15+k3s1

自动下载特定版本安装

1	curl -sfL https://get.k3s.io \| INSTALL_K3S_VERSION="v1.22.15+k3s1" sh -

自定义token安装

1	curl -sfL https://get.k3s.io \| K3S_TOKEN=12345 sh -

配置

k3s 默认配置文件位于 /etc/rancher/k3s/config.yaml 此配置文件将在安装时使用

server

基于 server 的配置文件示例

write-kubeconfig-mode: "0644"
tls-san:
  - "foo.local"
node-label:
  - "foo=bar"
  - "something=amazing"

同样，基于CLI也可以配置参数

k3s server \
  --write-kubeconfig-mode "0644"    \
  --tls-san "foo.local"             \
  --node-label "foo=bar"            \
  --node-label "something=amazing"

直接修改 systemd 文件也更方便点。

# /etc/systemd/system/k3s.service
[Unit]
Description=Lightweight Kubernetes
Documentation=https://k3s.io
Wants=network-online.target
After=network-online.target

[Install]
WantedBy=multi-user.target

[Service]
Type=notify
EnvironmentFile=-/etc/default/%N
EnvironmentFile=-/etc/sysconfig/%N
EnvironmentFile=-/etc/systemd/system/k3s.service.env
KillMode=process
Delegate=yes
# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNOFILE=1048576
LimitNPROC=infinity
LimitCORE=infinity
TasksMax=infinity
TimeoutStartSec=0
Restart=always
RestartSec=5s
ExecStartPre=/bin/sh -xc '! /usr/bin/systemctl is-enabled --quiet nm-cloud-setup.service'
ExecStartPre=-/sbin/modprobe br_netfilter
ExecStartPre=-/sbin/modprobe overlay
ExecStart=/usr/local/bin/k3s \
    server \

安装的时候直接配置

cat /etc/rancher/k3s/config.yaml
write-kubeconfig-mode: "0644"
tls-san:
  - "aaa.xmomo.top"
node-label:
  - "env=aaa"
  - "use=inner"
  - "env-aaaa=1"
token: "dawdjioasjdiojwaoih"

# 不部署 metrics-server
ls /var/lib/rancher/k3s/server/manifests/metrics-server.skip

curl -sfL https://get.k3s.io | INSTALL_K3S_VERSION="v1.22.15+k3s1"    sh -