Add memcache flushing handler on db migrations

Flushing cache when schema changes occur to avoid drift between
what might be cached and what keystone queries expect.

Change-Id: Ibf8f3dd60d6f3c446a14dc8228fa005f12fcc840
Closes-Bug: 1793389

handlers/main.yml

@@ -164,6 +164,17 @@
   retries: 5
   delay: 2
 
+- name: Flush all of the cache in memcached
+  vars:
+    nc_command:
+      debian: nc -q 1 $(awk '/^\-l/ {print $2}' "/etc/memcached.conf" | awk -F, '{print $1}') $(awk '/^\-p/ {print $2}' "/etc/memcached.conf")
+      redhat: nc $(awk -F '-l' '/^OPTIONS/ {print $2}' "/etc/sysconfig/memcached" | awk -F ',' '{gsub(/"/, "", $1); print $1}' | awk -F '-' '{print $1}') 11211
+      suse: nc -w 1 $(awk -F '-l' '/^MEMCACHED_PARAMS/ {print $2}' "/etc/sysconfig/memcached" | awk -F ',' '{gsub(/"/, "", $1); print $1}' | awk -F '-' '{print $1}') 11211
+  shell: "echo 'flush_all' | {{ nc_command.get(ansible_os_family | lower) }}"
+  delegate_to: "{{ item }}"
+  with_items: "{{ groups.memcached_all }}"
+  listen: flush cache
+
 - meta: noop
   listen: Manage LB
   when: false

tasks/keystone_db_setup.yml

@@ -102,6 +102,7 @@
   when:
     - "ansible_local['openstack_ansible']['keystone']['need_db_expand'] | bool"
   run_once: yes
+  notify: flush cache
 
 - name: Perform a Keystone DB sync migrate
   command: "{{ keystone_bin }}/keystone-manage db_sync --migrate"
@@ -110,6 +111,7 @@
   when:
     - "ansible_local['openstack_ansible']['keystone']['need_db_migrate'] | bool"
   run_once: yes
+  notify: flush cache
 
 - name: Perform a Keystone DB sync contract
   command: "{{ keystone_bin }}/keystone-manage db_sync --contract"
@@ -119,3 +121,4 @@
     - "(keystone_all_software_updated | default('no')) | bool"
     - "ansible_local['openstack_ansible']['keystone']['need_db_contract'] | bool"
   run_once: yes
+  notify: flush cache