Having already outlined my reasons for using tarsnap for online backups this post will detail how exactly I'm using it.
The instructions on the tarsnap site are really very easy to follow. I was momentarily caught out by not importing the code signing key but after getting that sorted out it was fine. I did need to use sha256sum rather than sha256 as suggested. Installation went well and then I had a little play with creating, listing, deleting and recovering data from backups. It was at this point when my only real gripes with the software started to become obvious - you can't humanize the data size figures when using --list-archives and there is no shortcut for --list-archives. As gripes go these are fairly minor though and everything else works nicely.
With the tarsnap client running on my server it was time to automate my backups. I put together a small script which creates a dump of my database and then creates a new backup with the tarsnap client.
#!/bin/bashdateString=`date+%F`echo"Beginningbackupfor $dateString" >>/home/streety/sources/backup/tarsnap.log
#dumpthemysqldatabaserm-f/home/streety/mysql-backup.sqlmysqldump--user=backup-ppassword--all-databases>/home/streety/mysql-backup.sql
#backuptotarsnaptarsnap-c-flinode-jscom-$dateString/home/streety/etc/apache2echo"Backupcompletefor $dateString" >>/home/streety/sources/backup/tarsnap.logThat script worked fine when I ran it from the shell but cron didn't seem to be running it. I needed to specify the path to the tarsnap script. Easily enough done.
PATH=/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/binMAILTO=jonathan@jonathanstreet.com
# mhdommondowcommand
5 0 ***/home/streety/sources/backup/backup.sh>>/home/streety/sources/backup/output.log 2>&1
With everything working I wanted to get permissions set up. Again this was very easy.
tarsnap-keymgmt--outkeyfile/root/limited-tarsnap.key-r-w/root/tarsnap.keyThe original key is then removed from the system and kept in a secure place. The new limited key should allow us to create and read from backups but not to delete them.
streety@jonathanstreet:~$ tarsnap-c-fanothertestbackup/home/streetytarsnap:fopen(/root/tarsnap.key):Permissiondeniedtarsnap:Cannotreadkeyfile:/root/tarsnap.keystreety@jonathanstreet:~$ sudo !!
sudotarsnap-c-fanothertestbackup/home/streety[sudo]passwordforstreety:tarsnap:Removingleading'/'frommembernamesTotalsizeCompressedsizeAllarchives 1804387231 685263319
(uniquedata) 481384333 178645934
Thisarchive 746610352 296516102
Newdata 721055 196300
streety@jonathanstreet:~$ tarsnap--list-archivestarsnap:fopen(/root/tarsnap.key):Permissiondeniedtarsnap:Cannotreadkeyfile:/root/tarsnap.keystreety@jonathanstreet:~$ sudo !!
sudotarsnap--list-archivestestbackupanothertestbackuplinode-jscom-2009-11-30
streety@jonathanstreet:~$ sudotarsnap-d-fanothertestbackuptarsnap:Thedeleteauthorizationkeyisrequiredfor-dbutisnotavailableAs you can see I keep forgetting to use sudo but it all works. I can create backups, list the existing backups but I can't delete them, at least not from this server. Success.
I've been running this script for a little more than a month now and so far I'm very happy with it.