Update 'k3s: enable DNS resolution from host to k3s services'

k3s%3A-enable-DNS-resolution-from-host-to-k3s-services.md

@@ -0,0 +1,36 @@
+The following enables DNS resolution from host to k3s services for `default.svc.cluster.local` &  `svc.cluster.local` domains:
+
+```
+sudo mkdir -p /etc/systemd/resolved.conf.d
+cat <<EOF | sudo tee /etc/systemd/resolved.conf.d/k3s-kube-dns.conf
+[Resolve]
+DNS=$(kubectl -n kube-system get ep kube-dns -o jsonpath='{.subsets[0].addresses[0].ip}')
+FallbackDNS=
+Domains=default.svc.cluster.local svc.cluster.local
+DNSSEC=no
+Cache=no-negative
+EOF
+
+sudo systemctl restart systemd-resolved
+```
+
+Verification:
+
+```
+$ resolvectl
+
+Global
+         Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
+  resolv.conf mode: stub
+Current DNS Server: 10.42.0.2
+       DNS Servers: 10.42.0.2
+        DNS Domain: default.svc.cluster.local svc.cluster.local
+
+...
+
+$ host kube-dns.kube-system.svc.cluster.local
+kube-dns.kube-system.svc.cluster.local has address 10.43.0.10
+
+$ nc -vz kube-dns.kube-system.svc.cluster.local 53
+Connection to kube-dns.kube-system.svc.cluster.local (10.43.0.10) 53 port [tcp/domain] succeeded!
+```