🔧 Improve mk8s Terraform configuration

- instead of using 'kubectl wait nodes', we now use a simpler
  'kubectl get nodes -o name' and check if there is anything
  in the output. This seems to work better (as the previous
  method would sometimes remain stuck because the kubectl
  process would never get stopped by SIGPIPE).
- the shpod SSH NodePort is no longer hard-coded to 32222,
  which allows us to use e.g. vcluster to deploy multiple
  Kubernetes labs on a single 'home' (or 'outer') Kubernetes
  cluster.

prepare-labs/terraform/many-kubernetes/main.tf

@@ -62,7 +62,7 @@ resource "null_resource" "wait_for_nodes" {
     }
     command = <<-EOT
       while sleep 1; do
-        kubectl get nodes --watch | grep --silent --line-buffered . &&
+        kubectl get nodes -o name | grep --silent . &&
         kubectl wait node --for=condition=Ready --all --timeout=10m &&
         break
       done

prepare-labs/terraform/many-kubernetes/stage2.tmpl

@@ -90,7 +90,6 @@ resource "kubernetes_service" "shpod_${index}" {
       name = "ssh"
       port = 22
       target_port = 22
-      node_port = 32222
     }
     type = "NodePort"
   }
@@ -222,7 +221,10 @@ output "ip_addresses_of_nodes" {
   value = join("\n", [
   %{ for index, cluster in clusters ~}
     join("\t", concat(
-      [ random_string.shpod_${index}.result, "ssh -l k8s -p 32222" ],
+      [
+        random_string.shpod_${index}.result,
+        "ssh -l k8s -p $${kubernetes_service.shpod_${index}.spec[0].port[0].node_port}"
+      ],
       split(" ", file("./externalips.${index}"))
     )),
   %{ endfor ~}