Proxy local mysql socket over the network
As an user of OpenVZ it's often my task to migrate database driven web applications to separate environments. In recent versions of OpenVZ, bind mounting of sockets between virtual environments is prohibited. I had to find a way to proxy local connections to /var/run/mysqld/mysqld.sock to the remote mysql server.
First I've created a mysql user and group:
addgroup --system mysql adduser --system --home /var/run/mysqld --ingroup mysql mysql
Then I've installed and configured the excellent socat utility using launchtool.
db.vz is the address remote database host in the following executable launchtool configuration script
#!/usr/bin/launchtool -C tag = mysql-proxy daemon = yes user = mysql command = socat UNIX-LISTEN:/var/run/mysqld/mysqld.sock,fork,mode=0666 TCP:db.vz:3306,forever start dir = /var/run/mysqld wait times = 5 infinite runs = yes stats = yes launchtool output = syslog:mysql-proxy,LOG_DAEMON,LOG_INFO launchtool errors = syslog:mysql-proxy,LOG_DAEMON,LOG_ERR command output = syslog:mysql-proxy,LOG_DAEMON,LOG_INFO command errors = syslog:mysql-proxy,LOG_DAEMON,LOG_ERR
Update: this method seems reliable but rather slow when an application continously creates lots of connections - like does PHP
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