MySQL MGR叢集單主模式的自動搭建和自動化故障修復

阿新 • • 發佈：2019-08-24

/*
the waiting game:
儘管人生如此艱難，不要放棄；不要妥協；不要失去希望
*/

隨著MySQL MGR的版本的升級以及技術成熟，在把MHA拉下神壇之後， MGR越來越成為MySQL高可用的首選方案。
MGR的搭建並不算很複雜，但是有一系列手工操作步驟，為了簡便MGR的搭建和故障診斷，這裡完成了一個自動化的指令碼，來實現MGR的自動化搭建，自動化故障診斷以及修復。

MGR自動化搭建
為了簡便起見，這裡以單機多例項的模式進行測試，
先裝好三個MySQL例項，埠號分別是7001,7002,7003，其中7001作為寫節點，其餘兩個節點作為讀節，8000節點是筆者的另外一個測試節點，請忽略。

在指明主從節點的情況下，如下為mgr_tool.py一鍵搭建MGR叢集的測試demo

MGR故障模擬1

MGR節點故障自動監測和自愈實現，如下是搭建完成後的MGR叢集，目前叢集處於完全正常的狀態中。

主觀造成主從節點間binlog的丟失

在主節點上對於對於從節點丟失的資料操作，GTID無法找到對應的資料，組複製立馬熄火

非寫入節點出現錯誤

看下errorlog

如果是手動解決的話，還是GTID跳過錯誤事物的套路，master上的GTID資訊

嘗試跳過最新的一個事物ID，然後重新連線到組，可以正常連線到組，另外一個節點仍舊處於error狀態

stop group_replication; SET GTID_NEXT='6c81c118-e67c-4416-9cb0-2d573d178c1d:13'; BEGIN; COMMIT; set gtid_next='automatic';

另外一個節點類似，依次解決。

MGR故障模擬2

從節點脫離Group

這種情況倒是比較簡單，重新開始組複製即可，start group_replication

MGR故障自動檢測和修復

對於如上的兩種情況，

1，如果是從節點丟失主節點的事物，嘗試在從節點上跳過GTID，重新開始複製即可
2，如果是從節點非丟失主節點事物，嘗試在從節點重新開始組複製即可

實現程式碼如下

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)

對於故障型別1，GTID事物不一致的自動化修復

對於故障型別2從節點offline的自動化修復

完整的實現程式碼

該過程要求MySQL例項必須滿足MGR的基本條件，如果環境本身無法滿足MGR，一切都無從談起，因此要非常清楚MGR環境的最基本要求

完成的實現程式碼如下，花了一個下午寫的，目前來說存在以下不足
1，建立複製使用者的時候，沒有指定具體的slave機器，目前直接指定的%：create user repl@'%' identified by repl
2，對於slave的修復，目前無法整體修復，只能一臺一臺修復，其實就是少了一個迴圈slave機器判斷的過程
3，目前搭建之前都會reset master（不管主從，主要是清理可能的殘留GTID），因此只適合新環境的搭建
4，目前只支援offline和gtid事物衝突的錯誤型別修復，無法支援其他MGR錯誤型別的修復
5，開發環境是單機多例項模式測試，沒有在多機單例項模式下充分測試
以上都會逐步改善&加強。

# -*- 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)

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