refactor: improve hostname validation logic in OS precheck tasks (#2845)

Signed-off-by: redscholar <blacktiledhouse@gmail.com>

builtin/core/roles/precheck/kubernetes/tasks/main.yaml

@@ -45,7 +45,6 @@
   when:
     - .image_registry.auth.registry | empty | not
     - .image_registry.type | empty
-  run_once: true
   command: |
     HTTP_CODE=$(curl -skLI -w "%{http_code}" -u "{{ .image_registry.auth.username }}:{{ .image_registry.auth.password }}" "https://{{ .image_registry.auth.registry }}/v2/" -o /dev/null)
     if [[ "$HTTP_CODE" == "200" ]]; then

builtin/core/roles/precheck/os/tasks/main.yaml

@@ -1,9 +1,18 @@
 ---
-- name: OS | Fail if hostname is invalid
+- name: OS | Assert valid system hostname format
-  assert:
+  block:
-    that: .hostname | regexMatch "^[a-z0-9]([a-z0-9-]*[a-z0-9])?(\\.[a-z0-9]([a-z0-9-]*[a-z0-9])?)*$"
+    - name: OS | Validate inventory hostname is RFC-compliant
-    fail_msg: >-
+      when: .set_hostname
-      The hostname "{{ .hostname }}" is invalid. Hostnames must use only lowercase alphanumeric characters, '.', or '-', and must start and end with an alphanumeric character.
+      assert:
+        that: .inventory_hostname | regexMatch "^[a-z0-9]([a-z0-9-]*[a-z0-9])?(\\.[a-z0-9]([a-z0-9-]*[a-z0-9])?)*$"
+        fail_msg: >-
+          The hostname "{{ .inventory_hostname }}" is invalid. Hostnames must use only lowercase alphanumeric characters, '.', or '-', and must start and end with an alphanumeric character.
+    - name: OS | Validate current host system hostname is RFC-compliant
+      when: .set_hostname | not
+      assert:
+        that: .hostname | regexMatch "^[a-z0-9]([a-z0-9-]*[a-z0-9])?(\\.[a-z0-9]([a-z0-9-]*[a-z0-9])?)*$"
+        fail_msg: >-
+          The hostname "{{ .hostname }}" is invalid. Hostnames must use only lowercase alphanumeric characters, '.', or '-', and must start and end with an alphanumeric character.
 
 - name: OS | Fail if operating system is not supported
   assert: