Replace hardcoded 'master' group name with 'group_name_master' variable (#337)

For improved flexibility and maintainability.

* Update tasks in node role to use 'group_name_master' variable instead
  of hardcoded 'master' group name
* Update tasks in master role to use 'group_name_master' variable instead
  of hardcoded 'master' group name
* Update tasks in post role to use 'group_name_master' variable instead of
  hardcoded 'master' group name

Signed-off-by: Christian Berendt <berendt@23technologies.cloud>

roles/k3s_server_post/tasks/metallb.yml

@@ -5,7 +5,7 @@
     state: directory
     owner: "{{ ansible_user_id }}"
     mode: 0755
-  with_items: "{{ groups['master'] }}"
+  with_items: "{{ groups[group_name_master | default('master')] }}"
   run_once: true
 
 - name: Copy metallb CRs manifest to first master
@@ -14,14 +14,14 @@
     dest: "/tmp/k3s/metallb-crs.yaml"
     owner: "{{ ansible_user_id }}"
     mode: 0755
-  with_items: "{{ groups['master'] }}"
+  with_items: "{{ groups[group_name_master | default('master')] }}"
   run_once: true
 
 - name: Test metallb-system namespace
   command: >-
     k3s kubectl -n metallb-system
   changed_when: false
-  with_items: "{{ groups['master'] }}"
+  with_items: "{{ groups[group_name_master | default('master')] }}"
   run_once: true
 
 - name: Wait for MetalLB resources
@@ -66,7 +66,7 @@
   command: >-
     k3s kubectl -n metallb-system get endpoints webhook-service
   changed_when: false
-  with_items: "{{ groups['master'] }}"
+  with_items: "{{ groups[group_name_master | default('master')] }}"
   run_once: true
 
 - name: Apply metallb CRs