Add metallb installation for kubernetes

METALLB.md

@@ -0,0 +1,35 @@
+# Install MetalLB
+### Preparation
+```kubectl edit configmap -n kube-system kube-proxy```
+
+```yaml
+apiVersion: kubeproxy.config.k8s.io/v1alpha1
+kind: KubeProxyConfiguration
+mode: "ipvs"
+ipvs:
+  strictARP: true
+```
+
+OR
+
+```shell
+kubectl get configmap kube-proxy -n kube-system -o yaml | \
+sed -e "s/strictARP: false/strictARP: true/" | \
+kubectl diff -f - -n kube-system
+```
+
+```shell
+# 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
+```
+
+### Install
+```shell
+kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.10.3/manifests/namespace.yaml
+kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.10.3/manifests/metallb.yaml
+```
+
+### Reference
+- https://metallb.universe.tf/installation