terraform: create ubuntu vms and install kubernetes with kubeadm

kubernetes-kvm-terraform/join_command.tf

@@ -0,0 +1,58 @@
+resource "null_resource" "kubeadm_token" {
+  depends_on = [libvirt_domain.master]  # or whatever your master resource is
+
+  provisioner "remote-exec" {
+    inline = [
+      "until sudo kubectl --kubeconfig=/etc/kubernetes/admin.conf get nodes; do sleep 5; done",
+      "sudo kubeadm token create --print-join-command > /tmp/join-command.txt"
+    ]
+
+    connection {
+      type        = "ssh"
+      host        = local.master_ip
+      user        = "ubuntu"
+      private_key = file("~/.ssh/id_rsa")
+      timeout     = "10m"  # connection timeout
+    }
+  }
+
+  provisioner "local-exec" {
+    command = "scp -o StrictHostKeyChecking=no ubuntu@${local.master_ip}:/tmp/join-command.txt ./join-command.txt"
+  }
+}
+
+data "local_file" "join_command" {
+  depends_on = [null_resource.kubeadm_token]
+  filename   = "./join-command.txt"
+}
+
+# get kubeconfig and store it locally
+resource "null_resource" "kubeconfig" {
+
+  provisioner "remote-exec" {
+    inline = [
+      "until sudo ls -la /etc/kubernetes/admin.conf; do sleep 5; done",
+      "sudo cp /etc/kubernetes/admin.conf /tmp/admin.conf",
+      "sudo chown $(id -u):$(id -g) /tmp/admin.conf",
+      # Rewrite server address from localhost/internal to accessible IP
+      "sudo sed -i 's|server: https://.*:6443|server: https://${local.master_ip}:6443|' /tmp/admin.conf"
+    ]
+
+    connection {
+      type        = "ssh"
+      host        = local.master_ip
+      user        = "ubuntu"
+      private_key = file("~/.ssh/id_rsa")
+    }
+  }
+
+  provisioner "local-exec" {
+    command = "scp -o StrictHostKeyChecking=no ubuntu@${local.master_ip}:/tmp/admin.conf ./kubeconfig"
+  }
+}
+
+
+locals {
+  # parse: kubeadm join 192.168.1.10:6443 --token xxx --discovery-token-ca-cert-hash sha256:yyy
+  join_command = trimspace(data.local_file.join_command.content)
+}