K8s进阶之MetalLB实现LoadBalancer

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

http://10.0.0.150/

结尾：想要了解service的其它类型可以查看这篇文章：https://www.cnblogs.com/huangSir-devops/p/18859122