文章目錄
故事前景
接了個私活，需要安裝canal，canal需要mysql開啟
binlog功能，查看了mysql的配置文件，看到已經寫了log_bin參數，此時進入mysql，執行sql語句確認binlog功能是否為ON[sql語句：show variables like 'log_bin';]，結果顯示為OFF，於是開啟了排查之路
查看docker啟動時掛載了哪些目錄
docker inspect 9e33b294e948 | grep Binds -A 4
預期出現類似如下的輸出，以本地實際環境為准
docker run啟動的時候，-v參數所掛載的目錄，會在docker inspect的Binds這塊找到
"Binds": [
"/etc/localtime:/etc/localtime:ro",
"/data/mysql-test/conf:/etc/mysql",
"/data/mysql-test/data:/var/lib/mysql"
],
這時，查看一下本地持久化配置文件的目錄，發現，只有一個
my.cnf文件問題就出現在這一塊：本地直接使用
yum安裝的mysql，默認的配置文件存儲路徑是/etc/mysql/my.cnf但是
docker容器其實並非如此
# tree /data/mysql-test/conf
/data/mysql-test/conf
└── my.cnf
使用相同鏡像啟動一個mysql
因為只是查看一下mysql的配置文件情況，就簡單的啟動mysql即可
如果不給
-e MYSQL_ROOT_PASSWORD=root參數，容器無法在后台運行，就無法把配置文件獲取到宿主機
docker run -d -e MYSQL_ROOT_PASSWORD=root mysql:5.7
新建一個目錄用來存放容器內的mysql配置文件
mkdir -p /data/mysql-new/conf
復制容器內的mysql配置文件到本地
docker cp <容器ID>:/etc/mysql/ /data/mysql-new/conf/
查看mysql配置文件目錄結構
為什么要拿到本地？
反正也要拿到本地重新掛載，早晚都要拿，總不能手擼配置文件吧
# tree /data/mysql-new/conf/
/data/mysql-new/conf/
├── conf.d
│ ├── docker.cnf
│ ├── mysql.cnf
│ └── mysqldump.cnf
├── my.cnf -> /etc/alternatives/my.cnf
├── my.cnf.fallback
├── mysql.cnf
└── mysql.conf.d
└── mysqld.cnf
那么問題來了，這么多文件，到底哪個才是默認的配置文件呢，那就一個個看吧
conf/conf.d/docker.cnf
[mysqld]
skip-host-cache
skip-name-resolve
conf/conf.d/mysql.cnf
[mysql]
conf/conf.d/mysqldump.cnf
[mysqldump]
quick
quote-names
max_allowed_packet = 16M
conf/my.cnf
這個文件在本地看不了，因為他是一個軟連接文件，文件鏈接的路徑是
/etc/alternatives/my.cnf而
/etc/alternatives/my.cnf這個文件也是一個軟連接文件，文件的連接路徑是/etc/mysql/mysql.cnf咱也不知道官方為啥要這樣套娃，咱也不敢問
conf/my.cnf.fallback
#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
#
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html
# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
# Here is entries for some specific programs
# The following values assume you have at least 32M ram
!includedir /etc/mysql/conf.d/
conf/mysql.cnf
# Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License, version 2.0,
# as published by the Free Software Foundation.
#
# This program is also distributed with certain software (including
# but not limited to OpenSSL) that is licensed under separate terms,
# as designated in a particular file or component or in included license
# documentation. The authors of MySQL hereby grant you an additional
# permission to link the program and your derivative works with the
# separately licensed software that they have included with MySQL.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License, version 2.0, for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
!includedir /etc/mysql/conf.d/
!includedir /etc/mysql/mysql.conf.d/
mysql.conf.d/mysqld.cnf
# Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License, version 2.0,
# as published by the Free Software Foundation.
#
# This program is also distributed with certain software (including
# but not limited to OpenSSL) that is licensed under separate terms,
# as designated in a particular file or component or in included license
# documentation. The authors of MySQL hereby grant you an additional
# permission to link the program and your derivative works with the
# separately licensed software that they have included with MySQL.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License, version 2.0, for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#
# The MySQL Server configuration file.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html
[mysqld]
pid-file = /var/run/mysqld/mysqld.pid
socket = /var/run/mysqld/mysqld.sock
datadir = /var/lib/mysql
#log-error = /var/log/mysql/error.log
# By default we only accept connections from localhost
#bind-address = 127.0.0.1
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
真假配置文件已經顯而易見了
docker容器啟動的mysql默認的配置文件其實是
/etc/mysql/mysql.conf.d/mysqld.conf因此，如果需要將本地配置文件掛載到容器里面，只需要掛載這一個文件即可，此時我們修改本地的
mysql.conf.d/mysqld.conf文件，開啟binlog，並驗證是否修改成功
啟動mysql容器
精簡一下本地mysql配置文件目錄，就保留一個
mysqld.cnf文件即可
# tree /data/mysql-new/conf/
/data/mysql-new/conf/
└── mysqld.cnf
在
mysqld.cnf文件最后加上這兩行，用來開啟binlog日志
log_bin=mysql-bin
server_id=33091
啟動mysql容器
docker run -d \
-e MYSQL_ROOT_PASSWORD=root \
-v /etc/localtime:/etc/localtime \
-v /data/mysql-new/conf/mysqld.cnf:/etc/mysql/mysql.conf.d/mysqld.cnf \
-v /data/mysql-new/data:/var/lib/mysql \
-p 3309:3306 \
--name mysql-new \
mysql:5.7
數據庫就不進去了，直接使用
-e參數將結果返回到終端頁面
# mysql -uroot -p -P3309 -h192.168.100.200 -e "show variables like 'log_bin';"
Enter password:
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin | ON |
+---------------+-------+
此時，找到了為何已經啟動的mysql容器加載不到配置文件的原因了
同時，也學到了一個新的經驗，當容器需要持久化的時候，最好是簡單啟動一下這個容器，查看一下持久化目錄的結構以及是否存在依賴的情況，根據實際來選擇到底是目錄掛載，還是單配置文件掛載，避免本地錯誤目錄結構覆蓋了容器內的目錄結構，當一些配置沒有更新的時候，排查真的很頭疼
后續將會在頭腦清醒的時候去修復已經啟動的mysql環境，預知后事如何，請看下集 [填別人留下的坑，真的難頂]