概述
LoadBalancer官网文档：https://kubernetes.io/zh-cn/docs/concepts/services-networking/service/#loadbalancer
MetalLB官网地址：https://metallb.universe.tf/installation/
MetalLB仓库地址：https://github.com/metallb/metallb
LoadBalancer是实现负载均衡的Service，主要应用场景是云厂商环境，它能够为服务提供外部可访问的 IP 地址。这种类型的服务通过云服务提供商的负载均衡器实现，允许外部流量进入集群中的 Pod。
MetalLB 是一个为 Kubernetes 集群提供负载均衡的开源项目。在裸机环境中，Kubernetes 原生的 LoadBalancer 服务类型无法直接使用，因为云厂商的负载均衡器在裸机环境中不可用。MetalLB 通过实现标准的负载均衡器行为，填补了这一空白。
MetalLB主要功能
- 地址分配：MetalLB 可以从预配置的 IP 地址池中分配 IP 地址给 LoadBalancer 类型的服务。
- 负载均衡实现：支持两种主要的负载均衡模式：
- Layer 2 模式：通过 ARP/NDP 协议响应，将流量直接转发到节点。
- BGP 模式：通过边界网关协议与网络设备交换路由信息。
- 健康检查：自动检测节点健康状态，确保流量不会被发送到不可用的节点。
部署MetalLB
# 下载 [root@master01 ~/metalLB]# wget https://raw.githubusercontent.com/metallb/metallb/v0.14.9/config/manifests/metallb-frr.yaml # 配置镜像源，解决镜像拉不下来 [root@master01 ~/metalLB]# sed -i s#quay.io#quay.m.daocloud.io#g metallb-frr.yaml # 应用资源文件 [root@master01 ~/metalLB]# kubectl apply -f metallb-frr.yaml # 检查各种资源的启动状态 [root@master01 ~/metalLB]# kubectl get all -o wide -n metallb-system NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES pod/controller-749d99c9bf-89jdj 1/1 Running 1 (83s ago) 6m3s 100.95.185.241 node02 <none> <none> pod/speaker-69stl 4/4 Running 0 11m 10.0.0.31 node01 <none> <none> pod/speaker-lg2fp 4/4 Running 0 11m 10.0.0.30 master01 <none> <none> pod/speaker-xhh4v 4/4 Running 0 11m 10.0.0.32 node02 <none> <none> NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR service/metallb-webhook-service ClusterIP 10.96.3.91 <none> 443/TCP 11m component=controller NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE CONTAINERS IMAGES SELECTOR daemonset.apps/speaker 3 3 3 3 3 kubernetes.io/os=linux 11m frr,reloader,frr-metrics,speaker quay.m.daocloud.io/frrouting/frr:9.1.0,quay.m.daocloud.io/frrouting/frr:9.1.0,quay.m.daocloud.io/frrouting/frr:9.1.0,quay.m.daocloud.io/metallb/speaker:v0.14.9 app=metallb,component=speaker NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR deployment.apps/controller 1/1 1 1 11m controller quay.m.daocloud.io/metallb/controller:v0.14.9 app=metallb,component=controller NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR replicaset.apps/controller-749d99c9bf 1 1 1 11m controller quay.m.daocloud.io/metallb/controller:v0.14.9 app=metallb,component=controller,pod-template-hash=749d99c9bf 创建地址池配置
# 定义清单文件 [root@master01 ~/metalLB]# cat ippool.yaml apiVersion: metallb.io/v1beta1 kind: IPAddressPool metadata: name: first-pool namespace: metallb-system spec: addresses: # 注意改为你自己为MetalLB分配的IP地址 - 10.0.0.150-10.0.0.180 # 创建地址池 [root@master01 ~/metalLB]# kubectl apply -f ippool.yaml ipaddresspool.metallb.io/first-pool created # 检查配置 [root@master01 ~/metalLB]# kubectl get IPAddressPool -n metallb-system NAME AUTO ASSIGN AVOID BUGGY IPS ADDRESSES first-pool true false ["10.0.0.150-10.0.0.180"] 创建L2广告配置
# 定义资源文件 [root@master01 ~/metalLB]# cat l2.yaml apiVersion: metallb.io/v1beta1 kind: L2Advertisement metadata: name: example # 注意名称空间 namespace: metallb-system spec: ipAddressPools: # 地址池的名称 - first-pool # 创建l2广告配置 [root@master01 ~/metalLB]# kubectl apply -f l2.yaml l2advertisement.metallb.io/example created # 获取l2的配置 [root@master01 ~/metalLB]# kubectl get L2Advertisement -n metallb-system NAME IPADDRESSPOOLS IPADDRESSPOOL SELECTORS INTERFACES example ["first-pool"] 创建deploy
# 定义资源清单 [root@master01 ~/deploy]# cat deploy-nginx.yaml apiVersion: apps/v1 kind: Deployment metadata: name: deployment-nginx namespace: default spec: # 设置Pod的副本数量 replicas: 3 selector: # 标签匹配规则 matchLabels: app: nginx template: metadata: name: pod-nginx labels: app: nginx spec: containers: - name: container-nginx image: nginx:1.14.1 restartPolicy: Always # 创建deploy [root@master01 ~/deploy]# kubectl apply -f deploy-nginx.yaml deployment.apps/deployment-nginx created # 检查是否启动 [root@master01 ~/deploy]# kubectl get deploy NAME READY UP-TO-DATE AVAILABLE AGE deployment-nginx 3/3 3 3 108s 创建LoadBalancer的service
[root@master01 ~/service]# cat service-loadbanlacer.yaml apiVersion: v1 kind: Service metadata: name: loadbalancer-svc spec: # 指定svc的类型为LoadBalancer type: LoadBalancer selector: app: nginx ports: - port: 80 targetPort: 80 nodePort: 32000 [root@master01 ~/service]# kubectl apply -f service-loadbanlacer.yaml service/loadbalancer-svc created # 注意EXTERNAL-IP这一列，IP地址会在MetalLB分配的IP地址范围之内 [root@master01 ~/service]# kubectl get svc loadbalancer-svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE loadbalancer-svc LoadBalancer 10.96.0.141 10.0.0.150 80:32000/TCP 19s 访问测试
在宿主机上进行curl访问
[root@master01 ~/service]# curl 10.0.0.150:80 <!DOCTYPE html> <html> <head> <title>Welcome to nginx!</title> <style> 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> 通过浏览器访问
结尾：想要了解service的其它类型可以查看这篇文章：K8s新手系列之Service资源
