MDEV-10004: Galera's pc.recovery process fails in 10.1 with systemd

Galera recovery process works in two phases. In the first
phase, mysqld is started as non-daemon with --wsrep-recover
to recover and fetch the last logged global transaction ID.
This ID is then used in second phase as the start position
(--wsrep-start-position=XX) to start mysqld as daemon.

As this process was implemented in mysqld_safe script, the
recovery did not work when server was started using systemd.

Fixed by introducing a shell script (wsrep_recovery.sh) that
mimics the first phase of the recovery process.

2 files changed, 32 insertions, 3 deletions

diff --git a/support-files/mariadb.service.in b/support-files/mariadb.service.in
index b18674bea46..55202c696fb 100644
--- a/support-files/mariadb.service.in
+++ b/support-files/mariadb.service.in
@@ -48,6 +48,14 @@ CapabilityBoundingSet=CAP_IPC_LOCK
 # Execute pre and post scripts as root, otherwise it does it as User=
 PermissionsStartOnly=true
 
+# Perform automatic wsrep recovery. When server is started without wsrep,
+# galera_recovery simply returns an empty string. In any case, however,
+# the script is not expected to return with a non-zero status.
+# It is always safe to unset _WSREP_START_POSITION environment variable.
+ExecStartPre=/bin/sh -c "systemctl unset-environment _WSREP_START_POSITION"
+ExecStartPre=/bin/sh -c "VAR=`/usr/bin/galera_recovery`; [ $? -eq 0 ] && \
+ systemctl set-environment _WSREP_START_POSITION=$VAR || exit 1"
+
 # Needed to create system tables etc.
 # ExecStartPre=/usr/bin/mysql_install_db -u mysql
 
@@ -57,9 +65,12 @@ PermissionsStartOnly=true
 # This isn't a replacement for my.cnf.
 # _WSREP_NEW_CLUSTER is for the exclusive use of the script galera_new_cluster
 @SYSTEMD_EXECSTARTPRE@
-ExecStart=/usr/sbin/mysqld $MYSQLD_OPTS $_WSREP_NEW_CLUSTER
+ExecStart=/usr/sbin/mysqld $MYSQLD_OPTS $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION
 @SYSTEMD_EXECSTARTPOST@
 
+# Unset _WSREP_START_POSITION environment variable.
+ExecStartPost=/bin/sh -c "systemctl unset-environment _WSREP_START_POSITION"
+
 KillMode=process
 KillSignal=SIGTERM
 
diff --git a/support-files/mariadb@.service.in b/support-files/mariadb@.service.in
index ff87b66bf3c..18adf0e0eac 100644
--- a/support-files/mariadb@.service.in
+++ b/support-files/mariadb@.service.in
@@ -55,6 +55,21 @@ CapabilityBoundingSet=CAP_IPC_LOCK
 # Execute pre and post scripts as root, otherwise it does it as User=
 PermissionsStartOnly=true
 
+# Perform automatic wsrep recovery. When server is started without wsrep,
+# galera_recovery simply returns an empty string. In any case, however,
+# the script is not expected to return with a non-zero status.
+# It is always safe to unset _WSREP_START_POSITION%I environment variable.
+ExecStartPre=/bin/sh -c "systemctl unset-environment _WSREP_START_POSITION%I"
+ExecStartPre=/bin/sh -c "VAR=`/usr/bin/galera_recovery             \
+  --defaults-file=@INSTALL_SYSCONF2DIR@/my%I.cnf`; [ $? -eq 0 ] && \
+  systemctl set-environment _WSREP_START_POSITION%I=$VAR || exit 1"
+# Alternate: (remove ConditionPathExists above)
+# use [mysqld.INSTANCENAME] as sections in my.cnf
+#
+#ExecStartPre=/bin/sh -c "VAR=`/usr/bin/galera_recovery \
+# --defaults-group-suffix=%I`; [ $? -eq 0 ] &&          \
+# systemctl set-environment _WSREP_START_POSITION%I=$VAR || exit 1"
+
 # Needed to create system tables etc.
 # ExecStartPre=/usr/bin/mysql_install_db -u mysql
 
@@ -67,12 +82,15 @@ PermissionsStartOnly=true
 # Note: Place $MYSQLD_OPTS at the very end for its options to take precedence.
 
 ExecStart=/usr/sbin/mysqld --defaults-file=@INSTALL_SYSCONF2DIR@/my%I.cnf \
-  $_WSREP_NEW_CLUSTER $MYSQLD_OPTS
+  $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION%I $MYSQLD_OPTS
 # Alternate: (remove ConditionPathExists above)
 # use [mysqld.INSTANCENAME] as sections in my.cnf
 #
 # ExecStart=/usr/sbin/mysqld --defaults-group-suffix=%I \
-# $_WSREP_NEW_CLUSTER $MYSQLD_OPTS
+# $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION%I $MYSQLD_OPTS
+
+# Unset _WSREP_START_POSITION environment variable.
+ExecStartPost=/bin/sh -c "systemctl unset-environment _WSREP_START_POSITION%I"
 
 KillMode=process
 KillSignal=SIGTERM