云原生之初探 MetalLB

安装MetalLB 是一个为 Kubernetes 提供负载均衡服务的组件。Kubernetes 本身不提供内置的负载均衡器实现，特别是在裸机（非云环境）部署时。因此，当你在这样的环境中运行 Kubernetes，并希望提供外部访问到集群内的服务时，MetalLB 就变得非常有用。

MetalLB 支持两种主要的负载均衡模式：

  1. Layer 2 (数据链路层)：使用 ARP/NDP 协议，基于 MAC 地址进行通讯。简而言之，当一个 IP 地址被分配给一个服务时，MetalLB 会确保集群内的网络设备知道如何将数据转发到正确的节点。
  3. BGP (边界网关协议)：在这种模式下，MetalLB 与集群边界的路由器进行 BGP 会话，动态地告诉路由器如何路由到集群内部的 IP 地址。

MetalLB 的主要优点是它允许在没有特定云提供商的支持下，使用裸机硬件环境的 Kubernetes 集群提供外部可访问的负载均衡服务。这对于需要在自己的数据中心、边缘位置或其他非标准环境中运行 Kubernetes 的组织特别有用。

安装准备

If you’re using kube-proxy in IPVS mode, since Kubernetes v1.14.2 you have to enable strict ARP mode.

执行下述命令启用 strictARP

# see what changes would be made, returns nonzero returncode if different
kubectl get configmap kube-proxy -n kube-system -o yaml | \
sed -e "s/strictARP: false/strictARP: true/" | \
kubectl diff -f - -n kube-system

# actually apply the changes, returns nonzero returncode on errors only
kubectl get configmap kube-proxy -n kube-system -o yaml | \
sed -e "s/strictARP: false/strictARP: true/" | \
kubectl apply -f - -n kube-system

安装

安装 MetaILB 0.13.10 (安装到 ns:metallb-system 下)

kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.13.10/config/manifests/metallb-native.yaml

日志

root@l2:~# kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.13.10/config/manifests/metallb-native.yaml

Warning: resource namespaces/metallb-system is missing the kubectl.kubernetes.io/last-applied-configuration annotation which is required by kubectl apply. kubectl apply should only be used on resources created declaratively by either kubectl create --save-config or kubectl apply. The missing annotation will be patched automatically.
namespace/metallb-system configured
customresourcedefinition.apiextensions.k8s.io/addresspools.metallb.io created
customresourcedefinition.apiextensions.k8s.io/bfdprofiles.metallb.io created
customresourcedefinition.apiextensions.k8s.io/bgpadvertisements.metallb.io created
customresourcedefinition.apiextensions.k8s.io/bgppeers.metallb.io created
customresourcedefinition.apiextensions.k8s.io/communities.metallb.io created
customresourcedefinition.apiextensions.k8s.io/ipaddresspools.metallb.io created
customresourcedefinition.apiextensions.k8s.io/l2advertisements.metallb.io created
serviceaccount/controller created
serviceaccount/speaker created
role.rbac.authorization.k8s.io/controller created
role.rbac.authorization.k8s.io/pod-lister created
clusterrole.rbac.authorization.k8s.io/metallb-system:controller created
clusterrole.rbac.authorization.k8s.io/metallb-system:speaker created
rolebinding.rbac.authorization.k8s.io/controller created
rolebinding.rbac.authorization.k8s.io/pod-lister created
clusterrolebinding.rbac.authorization.k8s.io/metallb-system:controller created
clusterrolebinding.rbac.authorization.k8s.io/metallb-system:speaker created
configmap/metallb-excludel2 created
secret/webhook-server-cert created
service/webhook-service created
deployment.apps/controller created
daemonset.apps/speaker created
validatingwebhookconfiguration.admissionregistration.k8s.io/metallb-webhook-configuration created

配置 External IP Pool

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: default
  namespace: metallb-system
spec:
  addresses:
    - 192.168.36.139-192.168.36.200  # 手动配置IP范围
  autoAssign: true

---
apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
  name: default
  namespace: metallb-system
spec:
  ipAddressPools:
    - default

测试

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx
          ports:
            - name: http
              containerPort: 80

---
apiVersion: v1
kind: Service
metadata:
  name: nginx
spec:
  ports:
    - name: http
      port: 80
      protocol: TCP
      targetPort: 80
  selector:
    app: nginx
  type: LoadBalancer

检查 ip

root@l2:/etc/kubernetes/plugin/metallb-system# kubectl get service | grep nginx
nginx                  LoadBalancer   10.96.5.118      192.168.36.140   80:32582/TCP    4m57s

访问测试

root@l2:/etc/kubernetes/plugin/metallb-system# curl http://192.168.36.140
<!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>

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