jbmurphy.com

I wanted to setup MySQL replication over ssh for a small WordPress database. I have a VM that lives in my house, I wanted to be able to bring it up, make it current, disconnect, and then hack away. Here is my proceedure.

On the master:

Setup the replication user (I had to use 127.0.0.1 becasue % did not let me connect from ssh):

grant replication slave on *.* TO repl@"127.0.0.1" identified by '[repl password]';

edit /etc/my.cnf

server-id=1
log-bin=mysql-bin
replicate-do-db=DB_TO_REPLICATE   #the name of the db you want to replicate.

From the slave:

edit /etc/my.cnf

server-id = 2
master-host = 127.0.0.1
master-user = repl
master-password = password
master-port = 7777
replicate-do-db = DB_TO_REPLICATE   #the name of the db you want to replicate.

Next, tunnel a ssh connection from slave to the source, and then make sure you can see the source databases:

ssh -f -N -L7777:127.0.0.1:3306 [email protected]
mysql -h 127.0.0.1 -P 7777 -e "show databases;"

Next create a local database:

mysql -e "create database DB_TO_REPLICATE;"

Next we want to find where the master’s log is and its position:

MASTERLOGPOS=$(mysql -h 127.0.0.1 -P 7777 --batch --skip-column-names -e "SHOW MASTER STATUS;" | cut -f2)
MASTERLOGFILE=$(mysql -h 127.0.0.1 -P 7777 --batch --skip-column-names -e "SHOW MASTER STATUS;" | cut -f1)

next we want to seed the local db

mysqldump -h 127.0.0.1 -P 7777 DB_TO_REPLICATE | mysql -u root DB_TO_REPLICATE;

and finally, tell the db to use the source as the Master:

mysql -e "use DB_TO_REPLICATE;CHANGE MASTER TO MASTER_LOG_FILE='"$MASTERLOGFILE"',MASTER_LOG_POS=$MASTERLOGPOS;"
mysql -e "start slave;"

To test I run:

mysql -e "show slave status\G;"

and I compare the following on the master and the client:

mysql -e "select id,post_parent,post_modified,post_title from jbmurphy_com.wp_posts"

I wanted to write a script that would copy a WordPress site to the local machine from a remote server (securely over ssh). This would allow me to set up a test environment or backup. First I need to make sure the site exists on the source server. Then I want to get the current wp-config settings, like the database name:

echo "Checking $SRCSERVER for a site named $SRCSITENAME"
CHECKCMD="ls /PATH/TO/$SRCSITENAME/wp-config.php | grep wp-config.php > /dev/null; echo \$?"
CHECKFILE=$(ssh $SRCSERVER $CHECKCMD)
if [ $CHECKFILE -eq 0 ]; then
        echo "Source Site $SRCSITENAME on $SRCSERVER exists"
        SRCMYSQLSITEUSER=$(ssh $SRCSERVER grep "DB_USER" /PATH/TO/$SRCSITENAME/wp-config.php | cut -f 2 -d " " | cut -f 2 -d "'")
        SRCMYSQLSITEPASS=$(ssh $SRCSERVER grep "DB_PASSWORD" /PATH/TO/$SRCSITENAME/wp-config.php | cut -f 2 -d " " | cut -f 2 -d "'")
        SRCMYSQLSITEDB=$(ssh $SRCSERVER grep "DB_NAME" /PATH/TO/$SRCSITENAME/wp-config.php | cut -f 2 -d " " | cut -f 2 -d "'")
        echo "Source mySQL Site Database:"$SRCMYSQLSITEDB
        echo "Source mySQL Site Username:"$SRCMYSQLSITEUSER
        echo "Source mySQL Site Password:"$SRCMYSQLSITEPASS
else
        echo "Source Site $SRCSITENAME on $SRCSERVER does not exist"
        exit;
fi

Next I provision a new site with a new virtual host, and I copy over the files:

echo "Copying site from $SRCSERVER:/PATH/TO/$SRCSITENAME/ to /PATH/TO/$DESTSITENAME"
rsync --archive $SRCSERVER:/PATH/TO/$SRCSITENAME/ /PATH/TO/$DESTSITENAME

Next I provision a new blank MySQL database with the name, username, and password received in the first part for code, then I copy over the db data via ssh:

echo "Copying mysql data from $SRCSERVER to local database name $DESTSITENAME"
ssh $SRCSERVER "mysqldump -u root $SRCMYSQLSITEDB" | mysql -u root $DESTSITENAME

Finally I run a couple of SQL queries to change the URL that WordPress has inside the DB.

echo "What is going to be the WordPress URL"
read NEWURL

OLDSITENAME=$(mysql --batch --skip-column-names -e "use $DESTSITENAME;select guid from wp_posts LIMIT 1;" | cut -d"/" -f3)
echo "Changing the wp_posts guids from $OLDSITENAME to $NewURL

mysql --batch --skip-column-names -e "use $DESTSITENAME;UPDATE wp_posts SET guid = REPLACE (guid, '"http://$OLDSITENAME"','"http://$NEWURL"');"

echo "Changing the home and siterurl to $NewURL"

mysql --batch --skip-column-names -e "use $DESTSITENAME;UPDATE wp_options SET option_value = replace(option_value, '"http://$OLDSITENAME"', '"http://$NEWURL"') WHERE option_name = 'home' OR option_name = 'siteurl';"