Add the MTU size to ping to catch network issues

Many times users hit this issue where nic templates set jumbo
frames properly but switches are not properly configured and this
situation creates random issues hard to troubleshoot ranging from
a CEPH cluster not forming to swift not syncing properly.  Adding
an early test for MTU sizes in the ansible playbooks should fail
early and put us on a path to early solve this issue instead of
spending a week or more trying to figure out why CEPH batch LVM
is not working.

Change-Id: I9e56c512a563c4b04f398581e87846901fe021d6

tripleo_ansible/roles/tripleo_nodes_validation/tasks/main.yml

@@ -33,13 +33,10 @@
     - ansible_facts.default_ipv4.gateway is defined
 
 - name: Check Controllers availability
-  command: "{{ (':' in controller) | ternary('ping6', 'ping') }} -w 10 -c 1 {{ controller }}"
-  retries: 10
-  delay: 60
+  include_tasks: ping.yml
   loop_control:
     loop_var: controller
   loop: "{{ tripleo_nodes_validation_ping_test_ips }}"
-  changed_when: false
   when:
     - tripleo_nodes_validation_validate_controllers_icmp|bool
     - tripleo_nodes_validation_ping_test_ips | length > 0

tripleo_ansible/roles/tripleo_nodes_validation/tasks/ping.yml

@@ -0,0 +1,40 @@
+---
+# Copyright 2021 Red Hat, Inc.
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+- name: Get nic for ping
+  shell: |-
+    ip ro get {{ controller }} | head -1 | sed 's/.*dev \(.*\) src.*/\1/'
+  register: nic_for_ping
+
+- name: network availability validation block
+  block:
+    - name: Get MTU for {{ nic_for_ping.stdout }}
+      shell: |-
+        ip link show {{ nic_for_ping.stdout }} | head -1 | sed 's/.*mtu \(.*\) qdisc.*/\1/'
+      register: mtu_for_nic
+
+    - name: Check IP responsiveness
+      command: "{{ (':' in controller) | ternary('ping6', 'ping') }} -w 10 -c 1 {{ controller }}"
+      retries: 10
+      delay: 60
+      changed_when: false
+
+    - name: Validate packet with given MTU size can reach controller
+      command: "{{ (':' in controller) | ternary('ping6', 'ping') }} -w 10 -s {{ mtu_for_nic.stdout | int - 28 }} -c 1 {{ controller }}"
+      retries: 10
+      delay: 60
+      changed_when: false
+  when: nic_for_ping.stdout != 'lo'