什么是 K3S
官网：k3s.io/
中文版指南：docs.rancher.cn/docs/k3s/_i...
K3s 是一个轻量级的 Kubernetes 发行版，它针对边缘计算、物联网等场景进行了高度优化，易于安装，全部在不到 100MB 的二进制文件中；非常适合
- Edge
- IoT
- CI
- Development (用的就是这个)
- ARM
- Embedding K8s
- Situations where a PhD in K8s clusterology is infeasible
可以理解为是 K8SLite 版，单词比 K8S 一半还少，所以叫 K3S
什么是 K3D
k3d 是一个轻量级的包装器，用于在 docker 中运行 k3s（Rancher Lab 的最小 Kubernetes 发行版）。
k3d 使得在 docker 中创建单节点和多节点 k3s 集群变得非常容易，例如在 Kubernetes 上进行本地开发。
对于我们研发人员，我们不希望花太多精力和时间去搭建和维护 K8S，那么我们使用 K3D 就能通过类似 docker 的方式来快速的构建 K3S 集群，所以两者加起来就相当于一个 K8S 了
目标
学习使用 k3d 创建比本地集群，并部署一个可访问的服务 nodeport/ingress ，并理清楚访问链路
下载工具
brew install k3d
1. 创建集群
根据下载的版本，需要用到两个 ghcr 仓库的镜像，使用代理提前下载好
bash
Copy
docker pull ghcr.nju.edu.cn/k3d-io/k3d-tools:5.6.3
docker tag ghcr.nju.edu.cn/k3d-io/k3d-tools:5.6.3 ghcr.io/k3d-io/k3d-tools:5.6.3
docker pull ghcr.nju.edu.cn/k3d-io/k3d-proxy:5.6.3
docker tag ghcr.nju.edu.cn/k3d-io/k3d-proxy:5.6.3 ghcr.io/k3d-io/k3d-proxy:5.6.31. 使用 k3d 创建单节点集群架构#
yaml
apiVersion: k3d.io/v1alpha5
kind: Simple
metadata:
name: dev-cluster
servers: 1
agents: 2
kubeAPI:
hostPort: "6449"
ports:
- port: 8085:80
nodeFilters:
- loadbalancer
- port: 8087:30080
nodeFilters:
- loadbalancer
- port: 8443:443
nodeFilters:
- loadbalancer
registries:
config: |
mirrors:
docker.io:
endpoint:
- https://docker.m.daocloud.io
quay.io:
endpoint:
- https://quay.m.daocloud.io
gcr.io:
endpoint:
- https://gcr.m.daocloud.io
k8s.gcr.io:
endpoint:
- https://k8s-gcr.m.daocloud.io
ghcr.io:
endpoint:
- https://ghcr.m.daocloud.io
registry.k8s.io:
endpoint:
- https://k8s.m.daocloud.io
configs:
docker.nju.edu.cn:
auth:执行如下命令
k3d cluster create --config ./cluster-example.yaml
shell
k3d cluster list
NAME SERVERS AGENTS LOADBALANCER
dev-cluster 1/1 2/2 true创建一个 server 节点，2 个 agents 节点 的集群，且集群的 30080 端口映射宿主机的 8087 端口，80 映射宿主机的 8085 (即 docker expose 的端口看 docker 容器可以看出来)
shell
k3d node list
NAME ROLE CLUSTER STATUS
k3d-dev-cluster-agent-0 agent dev-cluster running
k3d-dev-cluster-agent-1 agent dev-cluster running
k3d-dev-cluster-server-0 server dev-cluster running
k3d-dev-cluster-serverlb loadbalancer dev-cluster running
k3d-dev-cluster-tools dev-cluster running对应 docker 的 5 个容器
所以，宿主机，k3d, k3s ，docker 的关系如下
2. 创建可访问的服务
nodeport 服务#
简单的 nginx 服务
yaml
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: web
name: web
spec:
replicas: 1
selector:
matchLabels:
app: web
strategy: {}
template:
metadata:
labels:
app: web
spec:
containers:
- image: nginx
name: nginx
ports:
- containerPort: 80
resources:
limits:
cpu: 100m
memory: 256Mi
requests:
cpu: 80m
memory: 128Mi对应的 nodeport svc
yaml
apiVersion: v1
kind: Service
metadata:
labels:
app: web-service
name: app-service-nodeport
spec:
ports:
- name:
nodePort: 30080
port: 80
protocol: TCP
targetPort: 80
selector:
app: web
type: NodePortkubectl apply -f deploy-nginx.yaml && kubectl apply -f nginx-svc-nodeport.yaml
shell
k get pods,svc ⎈ k3d-dev-cluster
NAME READY STATUS RESTARTS AGE
pod/web-574cd456fb-wbk5x 1/1 Running 0 74m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/app-service-a ClusterIP 10.43.154.184 <none> 80/TCP 73m本地访问 localhost:8087
shell
curl localhost:8087
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
ingress#
使用当前目录下的文件的资源文件，创建工作负载
shell
./ingress
├── cluster-example.yaml
├── deploy-a.yaml
├── deploy-b.yaml
├── nginx-ing-a.yaml
├── nginx-ing-b.yaml
├── nginx-svc-a.yaml
└── nginx-svc-b.yaml
shell
k get pods,svc,ing ⎈ k3d-dev-cluster
NAME READY STATUS RESTARTS AGE
pod/web-574cd456fb-wbk5x 1/1 Running 0 92m
pod/web-a-6bbd7486b-rfsk5 1/1 Running 0 91m
pod/web-b-544fc48b65-r4sgt 1/1 Running 0 91m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.43.0.1 <none> 443/TCP 121m
service/app-service-a ClusterIP 10.43.154.184 <none> 80/TCP 91m
service/app-service-b ClusterIP 10.43.103.135 <none> 80/TCP 91m
service/app-service-nodeport NodePort 10.43.233.136 <none> 80:30080/TCP 58m
NAME CLASS HOSTS ADDRESS PORTS AGE
ingress.networking.k8s.io/app-ingress-a traefik localhost 172.23.0.3,172.23.0.4,172.23.0.5 80 91m
ingress.networking.k8s.io/nginx-ingress-b traefik localhost.k3d.ingress 172.23.0.3,172.23.0.4,172.23.0.5 80 91m因为用的是同一个镜像，我们需要进入 a 和 b 的 pod 中更改 nginx 默认的 html 内容来区分
shell
k exec -it -n default web-b-544fc48b65-r4sgt /bin/bash
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
root@web-b-544fc48b65-r4sgt:/# cd /usr/share/nginx/html/
root@web-b-544fc48b65-r4sgt:/usr/share/nginx/html# ls
50x.html index.html
root@web-b-544fc48b65-r4sgt:/usr/share/nginx/html# echo 'hello from app b' >> index.html本地只配置 host， 访问服务
127.0.0.1 localhost
127.0.0.1 localhost.k3d.ingress
访问链路#
BackendPodBackendServiceIngressControllerK3DClusterBrowserUserBackendPodBackendServiceIngressControllerK3DClusterBrowserUseralt[找到匹配的Ingress规则][未找到匹配的Ingress规则]alt[本地hosts文件有配置][本地hosts文件无配置]输入 localhost.k3d.ingress:90011进行DNS解析2域名解析为127.0.0.13发送HTTP请求到127.0.0.1:90014端口映射，请求到达5检查请求的Host头部和URL路径6确定对应的后端服务7通过服务发现找到后端Pod8将请求转发到目标端口9处理请求并生成响应10返回响应11返回响应12返回响应13渲染并显示响应内容14返回404等错误响应15DNS解析失败，请求终止16