Fix conditional galera restarts

The task files galera_add_node.yml and galera_bootstrap.yml in the
galera_server role both restart mysql based on conditions. These
conditions are incorrectly defined causing restarts to happen every time
.

This commit addresses several issues related to how these conditions are
defined and compared.

- The the pgrep pattern for the task 'Check if mysql is running' has
been modified so that is no longer matches the ansible shell command. It
also ignores errors generated by pgrep failing to find a match so that
it can be used by other tasks.

- The registered variables, used by the when clauses, have appropriately
defined changed attributes. This commit modifies the when clauses to
make use of them.

- The when clause for the tasks 'bootstrap cluster (initialise mysql
with --wsrep-new-cluster)' and 'Restart mysql' were always being met
because 'mysql_running != 0' should be 'mysql_running.rc != 0', they has
been adjusted to use the changed status.

Closes-bug: #1444308
Change-Id: Ib2879bfe9754575fd984a1f1d132d5a42b848e21

playbooks/roles/galera_server/tasks/galera_add_node.yml

@@ -14,9 +14,10 @@
 # limitations under the License.
 
 - name: Check if mysql is running
-  shell: "pgrep -fl mysqld"
+  shell: "pgrep -fl [m]ysqld"
   register: mysql_running
   changed_when: mysql_running.rc != 0
+  ignore_errors: True
   tags:
     - galera-bootstrap
 
@@ -33,9 +34,7 @@
   service:
     name: mysql
     state: restarted
-  when: >
-    "not wsrep_incoming_addresses.stdout|search('{{ ansible_ssh_host }}')" or
-    mysql_running != 0
+  when: wsrep_incoming_addresses|changed or mysql_running|changed
   tags:
     - galera-add-node
     - galera-bootstrap

playbooks/roles/galera_server/tasks/galera_bootstrap.yml

@@ -14,9 +14,10 @@
 # limitations under the License.
 
 - name: Check if mysql is running
-  shell: "pgrep -fl mysqld"
+  shell: "pgrep -fl [m]ysqld"
   register: mysql_running
   changed_when: mysql_running.rc != 0
+  ignore_errors: True
   tags:
     - galera-bootstrap
 
@@ -25,7 +26,7 @@
     mysql -e 'show status like "wsrep_cluster_size%"\G'|awk '/Value/{print $2}'
   register: wsrep_cluster_size
   changed_when: wsrep_cluster_size.stdout|search("1")
-  when: mysql_running.rc == 0
+  when: not mysql_running|changed
   tags:
     - galera-bootstrap
 
@@ -36,15 +37,16 @@
     pattern: mysqld
   register: mysqlstopped
   when: >
-    mysql_running.rc == 0 and
-    (wsrep_cluster_size.stdout | search("1") or wsrep_cluster_size.stderr | search("ERROR"))
+    (not mysql_running|changed) and
+    (wsrep_cluster_size|changed or wsrep_cluster_size.stderr | search("ERROR"))
   tags:
     - galera-bootstrap
 
 - name: Check if mysql is running
-  shell: "pgrep -fl mysqld"
+  shell: "pgrep -fl [m]ysqld"
   register: mysql_running
   changed_when: mysql_running.rc != 0
+  ignore_errors: True
   tags:
     - galera-bootstrap
 
@@ -53,6 +55,6 @@
     name: mysql
     state: restarted
     args: --wsrep-new-cluster
-  when: wsrep_cluster_size.stdout|search("1") or mysqlstopped|changed or mysql_running != 0
+  when: wsrep_cluster_size|changed or mysqlstopped|changed or mysql_running|changed
   tags:
     - galera-bootstrap