Test playbook using molecule (#67)

* Test cluster using molecule

* Fix detection of first control node

* Include --flannel-iface and --node-ip as k3s arguments

* Store logs of k3s-init.service as GitHub job artifacts

molecule/resources/verify/from_outside/tasks/test/get-nodes.yml

@@ -0,0 +1,17 @@
+---
+- name: Get all nodes in cluster
+  kubernetes.core.k8s_info:
+    kind: node
+    kubeconfig: "{{ kubecfg_path }}"
+  register: cluster_nodes
+
+- name: Assert that the cluster contains exactly the expected nodes
+  ansible.builtin.assert:
+    that: found_nodes == expected_nodes
+    success_msg: "Found nodes as expected: {{ found_nodes }}"
+    fail_msg: "Expected nodes {{ expected_nodes }}, but found nodes {{ found_nodes }}"
+  vars:
+    found_nodes: >-
+      {{ cluster_nodes | json_query('resources[*].metadata.name') | unique }}
+    expected_nodes: >-
+      {{ (groups['master'] + groups['node']) | unique }}