mysql_failover の --exec-after --exec-before の引数調査
メモ。
mysql_failover のサービス定義は
[Unit] Description=MySQL Failover After=network.target [Service] Type=forking Restart=always TimeoutSec=120 PIDFile=/var/run/mysql_failover.pid ExecStart=/usr/bin/mysqlfailover \ -vv \ --master=root@10.10.10.12 \ --discover-slaves-login=root \ --candidates=root@10.10.10.13,root@10.10.10.14 \ --pidfile=/var/run/mysql_failover.pid \ --interval 10 \ --failover-mode=auto \ --daemon=start \ --force \ --exec-before=/var/lib/mysql_failover/exec_before.sh \ --exec-after=/var/lib/mysql_failover/exec_after.sh \ --log=/var/log/mysql/failover.log [Install] WantedBy=multi-user.target
としてある。
--exec-{before|after}で指定したスクリプトの中身は
#! /bin/bash # print stdout cat - > /tmp/mysql_failover_before_stdout # print args echo $* > /tmp/mysql_failover_before_args
マスターを落としてログを見てみると
# tailf /var/log/mysql/failover.log 2016-12-25 20:39:07 PM INFO host: 10.10.10.12, port: 3306, role: MASTER, state: UP, gtid_mode: ON, health: OK, version: 5.6.35-log, master_log_file: mysql-bin.000004, master_log_pos: 191, IO_Thread: , SQL_Thread: , Secs_Behind: , Remaining_Delay: , IO_Error_Num: , IO_Error: , SQL_Error_Num: , SQL_Error: , Trans_Behind: 2016-12-25 20:39:07 PM INFO host: 10.10.10.13, port: 3306, role: SLAVE, state: UP, gtid_mode: ON, health: OK, version: 5.6.35-log, master_log_file: mysql-bin.000004, master_log_pos: 191, IO_Thread: Yes, SQL_Thread: Yes, Secs_Behind: 0, Remaining_Delay: No, IO_Error_Num: 0, IO_Error: , SQL_Error_Num: 0, SQL_Error: , Trans_Behind: 0 2016-12-25 20:39:07 PM INFO host: 10.10.10.14, port: 3306, role: SLAVE, state: UP, gtid_mode: ON, health: OK, version: 5.6.35-log, master_log_file: mysql-bin.000004, master_log_pos: 191, IO_Thread: Yes, SQL_Thread: Yes, Secs_Behind: 0, Remaining_Delay: No, IO_Error_Num: 0, IO_Error: , SQL_Error_Num: 0, SQL_Error: , Trans_Behind: 0 2016-12-25 20:39:07 PM INFO host: 10.10.10.15, port: 3306, role: SLAVE, state: UP, gtid_mode: ON, health: OK, version: 5.6.35-log, master_log_file: mysql-bin.000004, master_log_pos: 191, IO_Thread: Yes, SQL_Thread: Yes, Secs_Behind: 0, Remaining_Delay: No, IO_Error_Num: 0, IO_Error: , SQL_Error_Num: 0, SQL_Error: , Trans_Behind: 0 2016-12-25 20:39:26 PM INFO Master may be down. Waiting for 3 seconds. 2016-12-25 20:39:41 PM INFO Failed to reconnect to the master after 3 attemps. 2016-12-25 20:39:41 PM CRITICAL Master is confirmed to be down or unreachable. 2016-12-25 20:39:41 PM INFO Failover starting in 'auto' mode... 2016-12-25 20:39:41 PM INFO Checking eligibility of slave 10.10.10.13:3306 for candidate. 2016-12-25 20:39:41 PM INFO GTID_MODE=ON ... Ok 2016-12-25 20:39:41 PM INFO Replication user exists ... Ok 2016-12-25 20:39:41 PM INFO Candidate slave 10.10.10.13:3306 will become the new master. 2016-12-25 20:39:41 PM INFO Checking slaves status (before failover). 2016-12-25 20:39:41 PM INFO Preparing candidate for failover. 2016-12-25 20:39:41 PM INFO Missing transactions found on 10.10.10.14:3306. SELECT gtid_subset() = 0 2016-12-25 20:39:41 PM INFO Connecting candidate to 10.10.10.14:3306 as a temporary slave to retrieve unprocessed GTIDs. 2016-12-25 20:39:41 PM INFO Waiting for candidate to catch up to slave 10.10.10.14:3306. 2016-12-25 20:39:41 PM INFO Missing transactions found on 10.10.10.15:3306. SELECT gtid_subset() = 0 2016-12-25 20:39:41 PM INFO Connecting candidate to 10.10.10.15:3306 as a temporary slave to retrieve unprocessed GTIDs. 2016-12-25 20:39:41 PM INFO Waiting for candidate to catch up to slave 10.10.10.15:3306. 2016-12-25 20:39:41 PM INFO Creating replication user if it does not exist. 2016-12-25 20:39:41 PM INFO Spawning external script. 2016-12-25 20:39:41 PM INFO Script completed Ok. 2016-12-25 20:39:41 PM INFO Stopping slaves. 2016-12-25 20:39:41 PM INFO Performing STOP on all slaves. 2016-12-25 20:39:41 PM WARNING Executing stop on slave 10.10.10.13:3306 WARN - slave is not configured with this master 2016-12-25 20:39:41 PM INFO Executing stop on slave 10.10.10.13:3306 Ok 2016-12-25 20:39:41 PM WARNING Executing stop on slave 10.10.10.14:3306 WARN - slave is not configured with this master 2016-12-25 20:39:41 PM INFO Executing stop on slave 10.10.10.14:3306 Ok 2016-12-25 20:39:41 PM WARNING Executing stop on slave 10.10.10.15:3306 WARN - slave is not configured with this master 2016-12-25 20:39:41 PM INFO Executing stop on slave 10.10.10.15:3306 Ok 2016-12-25 20:39:41 PM INFO Switching slaves to new master. 2016-12-25 20:39:41 PM INFO Disconnecting new master as slave. 2016-12-25 20:39:41 PM INFO Execute on 10.10.10.13:3306: RESET SLAVE ALL 2016-12-25 20:39:41 PM INFO Starting slaves. 2016-12-25 20:39:41 PM INFO Performing START on all slaves. 2016-12-25 20:39:41 PM INFO Executing start on slave 10.10.10.14:3306 Ok 2016-12-25 20:39:41 PM INFO Executing start on slave 10.10.10.15:3306 Ok 2016-12-25 20:39:41 PM INFO Spawning external script. 2016-12-25 20:39:41 PM INFO Script completed Ok. 2016-12-25 20:39:41 PM INFO Checking slaves for errors. 2016-12-25 20:39:41 PM INFO 10.10.10.14:3306 status: Ok 2016-12-25 20:39:41 PM INFO 10.10.10.15:3306 status: Ok 2016-12-25 20:39:41 PM INFO Failover complete. 2016-12-25 20:39:41 PM INFO Discovering slaves for master at 10.10.10.13:3306 2016-12-25 20:39:41 PM INFO Discovering slave at 10.10.10.14:3306 2016-12-25 20:39:41 PM INFO Found slave: 10.10.10.14:3306 2016-12-25 20:39:41 PM INFO Server '10.10.10.14:3306' is using MySQL version 5.6.35-log. 2016-12-25 20:39:41 PM INFO Discovering slave at 10.10.10.15:3306 2016-12-25 20:39:41 PM INFO Found slave: 10.10.10.15:3306 2016-12-25 20:39:41 PM INFO Server '10.10.10.15:3306' is using MySQL version 5.6.35-log. 2016-12-25 20:39:46 PM INFO Unregistering existing instances from slaves. 2016-12-25 20:39:46 PM INFO Registering instance on new master 10.10.10.13:3306. 2016-12-25 20:39:46 PM INFO Master Information 2016-12-25 20:39:46 PM INFO Binary Log File: mysql-bin.000004, Position: 723, Binlog_Do_DB: N/A, Binlog_Ignore_DB: N/A 2016-12-25 20:39:46 PM INFO GTID Executed Set: ab1f57f3-ca8f-11e6-bbb9-525400225b53:1-2[...] 2016-12-25 20:39:46 PM INFO Getting health for master: 10.10.10.13:3306. 2016-12-25 20:39:46 PM INFO Health Status: 2016-12-25 20:39:46 PM INFO host: 10.10.10.13, port: 3306, role: MASTER, state: UP, gtid_mode: ON, health: OK, version: 5.6.35-log, master_log_file: mysql-bin.000004, master_log_pos: 723, IO_Thread: , SQL_Thread: , Secs_Behind: , Remaining_Delay: , IO_Error_Num: , IO_Error: , SQL_Error_Num: , SQL_Error: , Trans_Behind: 2016-12-25 20:39:46 PM INFO host: 10.10.10.14, port: 3306, role: SLAVE, state: UP, gtid_mode: ON, health: OK, version: 5.6.35-log, master_log_file: mysql-bin.000004, master_log_pos: 723, IO_Thread: Yes, SQL_Thread: Yes, Secs_Behind: 0, Remaining_Delay: No, IO_Error_Num: 0, IO_Error: , SQL_Error_Num: 0, SQL_Error: , Trans_Behind: 0 2016-12-25 20:39:46 PM INFO host: 10.10.10.15, port: 3306, role: SLAVE, state: UP, gtid_mode: ON, health: OK, version: 5.6.35-log, master_log_file: mysql-bin.000004, master_log_pos: 723, IO_Thread: Yes, SQL_Thread: Yes, Secs_Behind: 0, Remaining_Delay: No, IO_Error_Num: 0, IO_Error: , SQL_Error_Num: 0, SQL_Error: , Trans_Behind: 0 2016-12-25 20:39:59 PM INFO Discovering slaves for master at 10.10.10.13:3306 2016-12-25 20:40:00 PM INFO Discovering slave at 10.10.10.14:3306 2016-12-25 20:40:00 PM INFO Discovering slave at 10.10.10.15:3306 2016-12-25 20:40:00 PM INFO Master Information 2016-12-25 20:40:00 PM INFO Binary Log File: mysql-bin.000004, Position: 723, Binlog_Do_DB: N/A, Binlog_Ignore_DB: N/A 2016-12-25 20:40:00 PM INFO GTID Executed Set: ab1f57f3-ca8f-11e6-bbb9-525400225b53:1-2[...] 2016-12-25 20:40:00 PM INFO Getting health for master: 10.10.10.13:3306. 2016-12-25 20:40:00 PM INFO Health Status: 2016-12-25 20:40:00 PM INFO host: 10.10.10.13, port: 3306, role: MASTER, state: UP, gtid_mode: ON, health: OK, version: 5.6.35-log, master_log_file: mysql-bin.000004, master_log_pos: 723, IO_Thread: , SQL_Thread: , Secs_Behind: , Remaining_Delay: , IO_Error_Num: , IO_Error: , SQL_Error_Num: , SQL_Error: , Trans_Behind: 2016-12-25 20:40:00 PM INFO host: 10.10.10.14, port: 3306, role: SLAVE, state: UP, gtid_mode: ON, health: OK, version: 5.6.35-log, master_log_file: mysql-bin.000004, master_log_pos: 723, IO_Thread: Yes, SQL_Thread: Yes, Secs_Behind: 0, Remaining_Delay: No, IO_Error_Num: 0, IO_Error: , SQL_Error_Num: 0, SQL_Error: , Trans_Behind: 0 2016-12-25 20:40:00 PM INFO host: 10.10.10.15, port: 3306, role: SLAVE, state: UP, gtid_mode: ON, health: OK, version: 5.6.35-log, master_log_file: mysql-bin.000004, master_log_pos: 723, IO_Thread: Yes, SQL_Thread: Yes, Secs_Behind: 0, Remaining_Delay: No, IO_Error_Num: 0, IO_Error: , SQL_Error_Num: 0, SQL_Error: , Trans_Behind: 0
このログから Master が 10.10.10.12 → 10.10.10.13 にフェイルオーバーされたのがわかる
このとき、--exec-{before|after}の動作結果は
# cat /tmp/mysql_failover_{before|after}_stdout (なし) # cat /tmp/mysql_failover_{before|after}_args 10.10.10.12 3306 10.10.10.13 3306
つまり、標準入力ではなにもわたされず、引数で
$1 = 旧マスター IP $2 = 旧マスター Port $3 = 新マスター IP $4 = 新マスター Port
が渡されているのがわかる。
