Simplify usage of pre-remove role (#8334)

- Use builtin task scheduling of ansible (same task on each host)
  instead of manual looping on master

Benefits:
- One less play in remove-node.yml playbook
- Parralel node drain
- Drain parameters (timeout, grace period, retries,
  allow_ungraceful_removal) can be adjusted separately for each node
  with ansible variables

remove-node.yml

@@ -21,13 +21,6 @@
         msg: "Delete nodes confirmation failed"
       when: pause_result.user_input | default('yes') != 'yes'
 
-- hosts: kube_control_plane[0]
-  gather_facts: no
-  environment: "{{ proxy_disable_env }}"
-  roles:
-    - { role: kubespray-defaults }
-    - { role: remove-node/pre-remove, tags: pre-remove }
-
 - name: Gather facts
   import_playbook: facts.yml
 
@@ -36,6 +29,7 @@
   environment: "{{ proxy_disable_env }}"
   roles:
     - { role: kubespray-defaults, when: reset_nodes|default(True)|bool }
+    - { role: remove-node/pre-remove, tags: pre-remove }
     - { role: remove-node/remove-etcd-node }
     - { role: reset, tags: reset, when: reset_nodes|default(True)|bool }
 

roles/remove-node/pre-remove/tasks/main.yml

@@ -14,14 +14,12 @@
       --ignore-daemonsets
       --grace-period {{ drain_grace_period }}
       --timeout {{ drain_timeout }}
-      --delete-emptydir-data {{ hostvars[item]['kube_override_hostname']|default(item) }}
-  loop: "{{ node.split(',') | default(groups['kube_node']) }}"
+      --delete-emptydir-data {{ kube_override_hostname|default(inventory_hostname) }}
   # ignore servers that are not nodes
-  when: hostvars[item]['kube_override_hostname']|default(item) in nodes.stdout_lines
+  when: kube_override_hostname|default(inventory_hostname) in nodes.stdout_lines
   register: result
   failed_when: result.rc != 0 and not allow_ungraceful_removal
   delegate_to: "{{ groups['kube_control_plane']|first }}"
-  run_once: true
   until: result.rc == 0 or allow_ungraceful_removal
   retries: "{{ drain_retries }}"
   delay: "{{ drain_retry_delay_seconds }}"