MySQL MGR集群单主模式的自动搭建和自动化故障修复

随着MySQL MGR的版本的升级以及技术成熟，在把MHA拉下神坛之后， MGR越来越成为MySQL高可用的首选方案。
MGR的搭建并不算很复杂，但是有一系列手工操作步骤，为了简便MGR的搭建和故障诊断，这里完成了一个自动化的脚本，来实现MGR的自动化搭建，自动化故障诊断以及修复。

MGR自动化搭建
为了简便起见，这里以单机多实例的模式进行测试，
先装好三个MySQL实例，端口号分别是7001,7002,7003，其中7001作为写节点，其余两个节点作为读节，8000节点是笔者的另外一个测试节点，请忽略。
在指明主从节点的情况下，如下为mgr_tool.py一键搭建MGR集群的测试demo

MGR故障模拟1

MGR节点故障自动监测和自愈实现，如下是搭建完成后的MGR集群，目前集群处于完全正常的状态中。

主观造成主从节点间binlog的丢失

在主节点上对于对于从节点丢失的数据操作，GTID无法找到对应的数据，组复制立马熄火

非写入节点出现错误

看下errorlog

如果是手动解决的话，还是GTID跳过错误事物的套路，master上的GTID信息

尝试跳过最新的一个事物ID，然后重新连接到组，可以正常连接到组，另外一个节点仍旧处于error状态

stop group_replication;

SET GTID_NEXT='6c81c118-e67c-4416-9cb0-2d573d178c1d:13';

BEGIN; COMMIT;

set gtid_next='automatic'; 

另外一个节点类似，依次解决。

MGR故障模拟2

从节点脱离Group

这种情况倒是比较简单，重新开始组复制即可，start group_replication

MGR故障自动检测和修复

对于如上的两种情况，
1，如果是从节点丢失主节点的事物，尝试在从节点上跳过GTID，重新开始复制即可
2，如果是从节点非丢失主节点事物，尝试在从节点重新开始组复制即可

实现代码如下

def auto_fix_mgr_error(conn_master_dict,conn_slave_dict):
    group_replication_status = get_group_replication_status(conn_slave_dict)
    if(group_replication_status[0]["MEMBER_STATE"]=="ERROR" or group_replication_status[0]["MEMBER_STATE"] == "OFFLINE"):
        print(conn_slave_dict["host"]+str(conn_slave_dict["port"])+'------>'+group_replication_status[0]["MEMBER_STATE"])
        print("auto fixing......")
        while 1 > 0:
            master_gtid_list = get_gtid(conn_master_dict)
            slave_gtid_list = get_gtid(conn_slave_dict)
            master_executed_gtid_value = int((master_gtid_list[-1]["Executed_Gtid_Set"]).split("-")[-1])
            slave_executed_gtid_value = int(slave_gtid_list[-1]["Executed_Gtid_Set"].split("-")[-1])
            slave_executed_gtid_prefix = slave_gtid_list[-1]["Executed_Gtid_Set"].split(":")[0]
            slave_executed_skiped_gtid = slave_executed_gtid_value + 1
            if (master_executed_gtid_value > slave_executed_gtid_value):
                print("skip gtid and restart group replication,skiped gtid is "
                      + slave_gtid_list[-1]["Executed_Gtid_Set"].split(":")[-1].split("-")[0]
                      + ":"+str(slave_executed_skiped_gtid))
                slave_executed_skiped_gtid = slave_executed_gtid_prefix+":"+str(slave_executed_skiped_gtid)
                skip_gtid_on_slave(conn_slave_dict,slave_executed_skiped_gtid)
                time.sleep(10)
                start_group_replication(conn_slave_dict)
                if(get_group_replication_status(conn_slave_dict)[0]["MEMBER_STATE"]=="ONLINE"):
                    print("mgr cluster fixed,back to normal")
                    break
            else:
                start_group_replication(conn_slave_dict)
                if(get_group_replication_status(conn_slave_dict)[0]["MEMBER_STATE"]=="ONLINE"):
                    print("mgr cluster fixed,back to normal")
                break
    elif (group_replication_status[0]['MEMBER_STATE'] == 'ONLINE'):
        print("mgr cluster is normal,nothing to do")
        check_replication_group_members(conn_slave_dict)

对于故障类型1，GTID事物不一致的自动化修复

对于故障类型2从节点offline的自动化修复

完整的实现代码

该过程要求MySQL实例必须满足MGR的基本条件，如果环境本身无法满足MGR，一切都无从谈起，因此要非常清楚MGR环境的最基本要求

完成的实现代码如下，花了一个下午写的，目前来说存在以下不足
1，创建复制用户的时候，没有指定具体的slave机器，目前直接指定的%：create user repl@'%' identified by repl
2，对于slave的修复，目前无法整体修复，只能一台一台修复，其实就是少了一个循环slave机器判断的过程
3，目前搭建之前都会reset master（不管主从，主要是清理可能的残留GTID），因此只适合新环境的搭建
4，目前只支持offline和gtid事物冲突的错误类型修复，无法支持其他MGR错误类型的修复
5，开发环境是单机多实例模式测试，没有在多机单实例模式下充分测试
以上都会逐步改善&加强。

# -*- coding: utf-8 -*-

import pymysql
import logging
import time
import decimal

def execute_query(conn_dict,sql):
    conn = pymysql.connect(host=conn_dict['host'],
                           port=conn_dict['port'],
                           user=conn_dict['user'],
                           passwd=conn_dict['password'],
                           db=conn_dict['db'])
    cursor = conn.cursor(pymysql.cursors.DictCursor)
    cursor.execute(sql)
    list = cursor.fetchall()
    cursor.close()
    conn.close()
    return list

def execute_noquery(conn_dict,sql):
    conn = pymysql.connect(host=conn_dict['host'],
                           port=conn_dict['port'],
                           user=conn_dict['user'],
                           passwd=conn_dict['password'],
                           db=conn_dict['db'])
    cursor = conn.cursor()
    cursor.execute(sql)
    conn.commit()
    cursor.close()
    conn.close()
    return list

def get_gtid(conn_dict):
    sql = "show master status;"
    list = execute_query(conn_dict,sql)
    return list

def skip_gtid_on_slave(conn_dict,gtid):
    sql_1 = 'stop group_replication;'
    sql_2 = '''set gtid_next='{0}';'''.format(gtid)
    sql_3 = 'begin;'
    sql_4 = 'commit;'
    sql_5 = '''set gtid_next='automatic';'''

    try:
        execute_noquery(conn_dict, sql_1)
        execute_noquery(conn_dict, sql_2)
        execute_noquery(conn_dict, sql_3)
        execute_noquery(conn_dict, sql_4)
        execute_noquery(conn_dict, sql_5)
    except:
        raise

def get_group_replication_status(conn_dict):
    sql = '''select MEMBER_STATE from performance_schema.replication_group_members
            where (MEMBER_HOST = '{0}' or ifnull(MEMBER_HOST,'') = '')
            AND (MEMBER_PORT={1} or ifnull(MEMBER_PORT,'') ='') ; '''.format(conn_dict["host"], conn_dict["port"])
    result = execute_query(conn_dict,sql)
    if result:
        return result
    else:
        return None

def check_replication_group_members(conn_dict):
    print('-------------------------------------------------------')
    result = execute_query(conn_dict, " select * from performance_schema.replication_group_members; ")
    if result:
        column = result[0].keys()
        current_row = ''
        for key in column:
            current_row += str(key) + "    "
        print(current_row)

        for row in result:
            current_row = ''
            for key in row.values():
                current_row += str(key) + "    "
            print(current_row)
    print('-------------------------------------------------------')

def auto_fix_mgr_error(conn_master_dict,conn_slave_dict):
    group_replication_status = get_group_replication_status(conn_slave_dict)
    if(group_replication_status[0]["MEMBER_STATE"]=="ERROR" or group_replication_status[0]["MEMBER_STATE"] == "OFFLINE"):
        print(conn_slave_dict["host"]+str(conn_slave_dict["port"])+'------>'+group_replication_status[0]["MEMBER_STATE"])
        print("auto fixing......")
        while 1 > 0:
            master_gtid_list = get_gtid(conn_master_dict)
            slave_gtid_list = get_gtid(conn_slave_dict)
            master_executed_gtid_value = int((master_gtid_list[-1]["Executed_Gtid_Set"]).split("-")[-1])
            slave_executed_gtid_value = int(slave_gtid_list[-1]["Executed_Gtid_Set"].split("-")[-1])
            slave_executed_gtid_prefix = slave_gtid_list[-1]["Executed_Gtid_Set"].split(":")[0]
            slave_executed_skiped_gtid = slave_executed_gtid_value + 1
            if (master_executed_gtid_value > slave_executed_gtid_value):
                print("skip gtid and restart group replication,skiped gtid is "
                      + slave_gtid_list[-1]["Executed_Gtid_Set"].split(":")[-1].split("-")[0]
                      + ":"+str(slave_executed_skiped_gtid))
                slave_executed_skiped_gtid = slave_executed_gtid_prefix+":"+str(slave_executed_skiped_gtid)
                skip_gtid_on_slave(conn_slave_dict,slave_executed_skiped_gtid)
                time.sleep(10)
                start_group_replication(conn_slave_dict)
                if(get_group_replication_status(conn_slave_dict)[0]["MEMBER_STATE"]=="ONLINE"):
                    print("mgr cluster fixed,back to normal")
                    break
            else:
                start_group_replication(conn_slave_dict)
                if(get_group_replication_status(conn_slave_dict)[0]["MEMBER_STATE"]=="ONLINE"):
                    print("mgr cluster fixed,back to normal")
                break
    elif (group_replication_status[0]['MEMBER_STATE'] == 'ONLINE'):
        print("mgr cluster is normal,nothing to do")
        check_replication_group_members(conn_slave_dict)

'''
reset master
'''
def reset_master(conn_dict):
    try:
        execute_noquery(conn_dict, "reset master;")
    except:
        raise

def install_group_replication_plugin(conn_dict):
    get_plugin_sql = "SELECT name,dl FROM mysql.plugin WHERE name = 'group_replication';"
    install_plugin_sql = '''install plugin group_replication soname 'group_replication.so'; '''
    try:
        result = execute_query(conn_dict, get_plugin_sql)
        if not result:
            execute_noquery(conn_dict, install_plugin_sql)
    except:
        raise

def create_mgr_repl_user(conn_master_dict,user,password):
    try:
        reset_master(conn_master_dict)
        sql_exists_user = '''select user from mysql.user where user = '{0}'; '''.format(user)
        user_list = execute_query(conn_master_dict,sql_exists_user)
        if not user_list:
            create_user_sql = '''create user {0}@'%' identified by '{1}'; '''.format(user,password)
            grant_privilege_sql = '''grant replication slave on *.* to {0}@'%';'''.format(user)
            execute_noquery(conn_master_dict,create_user_sql)
            execute_noquery(conn_master_dict, grant_privilege_sql)
            execute_noquery(conn_master_dict, "flush privileges;")
    except:
        raise

def set_super_read_only_off(conn_dict):
    super_read_only_off = '''set global super_read_only = 0;'''
    execute_noquery(conn_dict, super_read_only_off)

def open_group_replication_bootstrap_group(conn_dict):
    sql = '''select variable_name,variable_value from performance_schema.global_variables where variable_name = 'group_replication_bootstrap_group';'''
    result = execute_query(conn_dict, sql)
    open_bootstrap_group_sql = '''set @@global.group_replication_bootstrap_group=on;'''
    if result and result[0]['variable_value']=="OFF":
        execute_noquery(conn_dict, open_bootstrap_group_sql)

def close_group_replication_bootstrap_group(conn_dict):
    sql = '''select variable_name,variable_value from performance_schema.global_variables where variable_name = 'group_replication_bootstrap_group';'''
    result = execute_query(conn_dict, sql)
    close_bootstrap_group_sql = '''set @@global.group_replication_bootstrap_group=off;'''
    if result and result[0]['variable_value'] == "ON":
        execute_noquery(conn_dict, close_bootstrap_group_sql)

def start_group_replication(conn_dict):
    start_group_replication = '''start group_replication;'''
    group_replication_status = get_group_replication_status(conn_dict)
    if not (group_replication_status[0]['MEMBER_STATE'] == 'ONLINE'):
        execute_noquery(conn_dict, start_group_replication)

def connect_to_group(conn_dict,repl_user,repl_password):
    connect_to_group_sql = '''change master to
                                    master_user='{0}',
                                    master_password='{1}'
                                    for channel 'group_replication_recovery'; '''.format(repl_user,repl_password)
    try:
        execute_noquery(conn_dict, connect_to_group_sql)
    except:
        raise

def start_mgr_on_master(conn_master_dict,repl_user,repl_password):
    try:
        set_super_read_only_off(conn_master_dict)
        reset_master(conn_master_dict)
        create_mgr_repl_user(conn_master_dict,repl_user,repl_password)
        connect_to_group(conn_master_dict,repl_user,repl_password)

        open_group_replication_bootstrap_group(conn_master_dict)
        start_group_replication(conn_master_dict)
        close_group_replication_bootstrap_group(conn_master_dict)

        group_replication_status = get_group_replication_status(conn_master_dict)
        if (group_replication_status[0]['MEMBER_STATE'] == 'ONLINE'):
            print("master added in mgr and run successfully")
            return True
    except:
        raise
        print("############start master mgr error################")
        exit(1)

def start_mgr_on_slave(conn_slave_dict,repl_user,repl_password):
    try:
        set_super_read_only_off(conn_slave_dict)
        reset_master(conn_slave_dict)
        connect_to_group(conn_slave_dict,repl_user,repl_password)
        start_group_replication(conn_slave_dict)
        # wait for 10
        time.sleep(10)
        # then check mgr status
        group_replication_status = get_group_replication_status(conn_slave_dict)
        if (group_replication_status[0]['MEMBER_STATE'] == 'ONLINE'):
            print("slave added in mgr and run successfully")
        if (group_replication_status[0]['MEMBER_STATE'] == 'RECOVERING'):
            print("slave is recovering")
    except:
        print("############start slave mgr error################")
        exit(1)

def auto_mgr(conn_master,conn_slave_1,conn_slave_2,repl_user,repl_password):
    install_group_replication_plugin(conn_master)
    master_replication_status = get_group_replication_status(conn_master)

    if not (master_replication_status[0]['MEMBER_STATE'] == 'ONLINE'):
        start_mgr_on_master(conn_master,repl_user,repl_password)

    slave1_replication_status = get_group_replication_status(conn_slave_1)
    if not (slave1_replication_status[0]['MEMBER_STATE'] == 'ONLINE'):
        install_group_replication_plugin(conn_slave_1)
        start_mgr_on_slave(conn_slave_1, repl_user, repl_user)

    slave2_replication_status = get_group_replication_status(conn_slave_2)
    if not (slave2_replication_status[0]['MEMBER_STATE'] == 'ONLINE'):
        install_group_replication_plugin(conn_slave_2)
        start_mgr_on_slave(conn_slave_2, repl_user, repl_user)

    check_replication_group_members(conn_master)

if __name__ == '__main__':
    conn_master  = {'host': '127.0.0.1', 'port': 7001, 'user': 'root', 'password': 'root', 'db': 'mysql', 'charset': 'utf8mb4'}
    conn_slave_1 = {'host': '127.0.0.1', 'port': 7002, 'user': 'root', 'password': 'root', 'db': 'mysql', 'charset': 'utf8mb4'}
    conn_slave_2 = {'host': '127.0.0.1', 'port': 7003, 'user': 'root', 'password': 'root', 'db': 'mysql', 'charset': 'utf8mb4'}
    repl_user = "repl"
    repl_password = "repl"
    #auto_mgr(conn_master,conn_slave_1,conn_slave_2,repl_user,repl_password)

    auto_fix_mgr_error(conn_master,conn_slave_1)
    check_replication_group_members(conn_master)

/*
the waiting game:尽管人生如此艰难，不要放弃；不要妥协；不要失去希望
*/