Run tcpdump separately from introspection

There are various issues with stopping tcpdump in shell script
in background so it won't affect other commands. Also for
moving to operators we need to separate these steps.
Run tcpdump in a different task.

Closes-Bug: #1880851

Change-Id: I38dc2a53c6bb56eaa916e84798dcd3c0fac3fa1a

roles/overcloud-prep-images/tasks/overcloud-prep-images.yml

@@ -74,6 +74,21 @@
   changed_when: true
   when: step_root_device_hints|bool
 
+- name: Run tcpdump during introspection in background
+  become: true
+  shell: >
+    {{ ansible_pkg_mgr }} -y install tcpdump;
+    tcpdump -U -i any port {{ step_introspect_debug_tcpdump_ports | join(' or port ') }}
+    -w {{ step_introspect_debug_tcpdump_log }} > /dev/null &
+  args:
+    executable: /bin/bash
+  async: 1
+  poll: 0
+  changed_when: false
+  when:
+    - step_introspect|bool
+    - step_introspect_debug|bool
+
 - name: Introspect overcloud images
   shell: >
     set -o pipefail &&
@@ -82,6 +97,12 @@
   changed_when: true
   when: step_introspect|bool
 
+- name: Stop tcpdump after introspection
+  become: true
+  command: pkill tcpdump
+  changed_when: false
+  failed_when: false
+
 - name: Inject ARA into mistral executor container image
   shell: >
     set -o pipefail &&

roles/overcloud-prep-images/templates/overcloud-introspect.sh.j2

@@ -8,15 +8,6 @@ set -eux
 
 source {{ working_dir }}/stackrc
 
-{% if step_introspect_debug|bool %}
-
-sudo {{ ansible_pkg_mgr }} -y install tcpdump
-sudo tcpdump -i any port {{ step_introspect_debug_tcpdump_ports | join(' or port ') }} -w {{ step_introspect_debug_tcpdump_log }} &
-sleep 1
-pidof_tcpdump=$(ps --ppid $! -o pid=)
-
-{% endif %}
-
 ## * Introspect hardware attributes of nodes.
 ## ::
 openstack overcloud node introspect --all-manageable
@@ -76,9 +67,4 @@ introspect 60m
 
 {% endif %}
 
-{% if step_introspect_debug|bool %}
-
-sudo kill $pidof_tcpdump
-
-{% endif %}
 ### --stop_docs