Fix boostrap pxc on systemd

Percona-cluster was quietly failing to bootstrap. The problem was brought to
light but not caused by a recent commit which added a service stop of mysql
before the bootstrap.

Systemd systems try to run: systemctl bootstrap-pxc mysql
Which returns: Unknown operation bootstrap-pxc.

This fix both handles systemd bootstrapping and is more verbose when a bootstrap fails.

Change-Id: Ifdaa3114fd2de315d2da8d2bd6a807e503d26dce
Partial-Bug: 1600001

hooks/percona_hooks.py

@@ -27,7 +27,6 @@ from charmhelpers.core.hookenv import (
     network_get_primary_address,
 )
 from charmhelpers.core.host import (
-    service,
     service_restart,
     service_start,
     file_hash,
@@ -91,6 +90,7 @@ from percona_utils import (
     register_configs,
     resolve_cnf_file,
     create_binlogs_directory,
+    bootstrap_pxc,
 )
 
 
@@ -176,8 +176,7 @@ def render_config_restart_on_changed(clustered, hosts, bootstrap=False):
     update_db_rels = False
     if file_hash(resolve_cnf_file()) != pre_hash or bootstrap:
         if bootstrap:
-            service('stop', 'mysql')
-            service('bootstrap-pxc', 'mysql')
+            bootstrap_pxc()
             # NOTE(dosaboy): this will not actually do anything if no cluster
             # relation id exists yet.
             notify_bootstrapped()

hooks/percona_utils.py

@@ -9,7 +9,8 @@ import uuid
 
 from charmhelpers.core.host import (
     lsb_release,
-    mkdir
+    mkdir,
+    service,
 )
 from charmhelpers.core.hookenv import (
     charm_dir,
@@ -27,6 +28,7 @@ from charmhelpers.core.hookenv import (
     WARNING,
     ERROR,
     cached,
+    status_set,
 )
 from charmhelpers.fetch import (
     apt_install,
@@ -350,6 +352,27 @@ def is_bootstrapped():
     return False
 
 
+def bootstrap_pxc():
+    """Bootstrap PXC
+    On systemd systems systemctl bootstrap-pxc mysql does not work.
+    Run service mysql bootstrap-pxc to bootstrap."""
+    service('stop', 'mysql')
+    bootstrapped = service('bootstrap-pxc', 'mysql')
+    if not bootstrapped:
+        try:
+            cmd = ['service', 'mysql', 'bootstrap-pxc']
+            subprocess.check_call(cmd)
+        except subprocess.CalledProcessError as e:
+            msg = 'Bootstrap PXC failed'
+            error_msg = '{}: {}'.format(msg, e)
+            status_set('blocked', msg)
+            log(error_msg, ERROR)
+            raise Exception(error_msg)
+        # To make systemd aware mysql is running after a bootstrap
+        service('start', 'mysql')
+    log("Bootstrap PXC Succeeded", DEBUG)
+
+
 def notify_bootstrapped(cluster_rid=None, cluster_uuid=None):
     if cluster_rid:
         rids = [cluster_rid]