selectively restoring a renamed database from a chunky sql dump file.

with a  multi GB dump.sql.gzip file, and the requirement is to restore one database from the multiple in the file, the first instinct is to break out some grep/sed/awk and generate a sub-set sql file that just contains the "CREATE DATABASE" and insert statements and apply that to the main database.

However if you have some requirement to rename the imported database, or some other import time alterations, this is something of ball-ache.

one way to un fuck this situation is to start another mysqld instance on another port, and then use the mysqldump/mysql tools to do the work of selecting and renaming the databases and tables as required...

centralized logging with logstash

Last week I migrated some services off servers in a rack that was being decommissioned.  There was a distinct lack of system documentation, either up to date or otherwise, so I thought configuring nagios, monit, and munin would be a good start to checking the performance and reliability of the service on the new instance.

It had been suggested that the development team have a log monitoring system based around the log4j library, however it turns out that this system is mostly reactive, and there were a few undocumented configurations that didn't make the migration, and caused some problems. So after some hasty "diff -r" and rsync everything seemed to be well.

But I decided that this weekend I am putting together a central logging management system using logstash and chef, that I can deploy zero config style to hosts via a cookbook recipe, to catch 404 and 503 errors and other alerts coming from remote systems in some timely manner.