How to automatically back up WordPress or ownCloud using cron jobs

Recently I set up WordPress for my research group in the Medical Ethics Unit. We will be blogging our journal clubs, posting links to our publications and upcoming events. In related news, my research group has been using DropBox to coordinate papers in progress, sharing of raw data, citations, and all manner of other information. This was working pretty well, but we have been bumping up against the upper limit of our capacity on DropBox for a while, so I installed ownCloud on the web host we got for the research group blog. I’m pretty happy with how nice it is to use and administer.

Of course one of our concerns is making sure that we don’t lose any data in the case of the failure of our web host. This is unlikely, but it does happen, and we don’t want to run into a situation where we try to log in to our cloud-based file storage / sharing service and find that months’ worth of research is gone forever.

For a few weeks, the following was more-or-less my workflow for making backups:

1. Log in to phpMyAdmin
2. Make a dump file of the WP database (choose database > Export > Save as file … )
3. Make a dump file of the ownCloud database
4. Save to computer and label with appropriate date
5. Log in to web server using FTP
6. Copy contents of WP’s /wp-content/ to a date-labelled folder on my computer
7. Copy contents of ownCloud’s /data/ to a date-labelled folder on my computer

This worked pretty well, except that it was a pain for me to have to do this every day, and I know that if I ever forgot to do it, that would be when something terrible happened. Fortunately for me, my boss mentioned that he had an old but still serviceable iMac sitting in his office that he wanted to put to some good purpose.

I decided to make a fully automatic setup that would make backups of our remotely hosted data and save it locally without any input on my part, so I can just forget about it. I made it with cron jobs.

Server side cron jobs

First, I set up some cron jobs on the server side. The first one waits until midnight every day, then dumps all the MySQL databases into a gzipped file on my web host, then zips up the WordPress /wp-content/ and ownCloud /data/ folders and puts them in the backup folder as well. The second server-side cron job empties the backup folder every day at 23h00.

• 0 0 * * * PREFIX=`date +%y-%m-%d`; mysqldump -u USERNAME -h HOSTNAME -pPASSWORD –all-databases | gzip > /path/to/backup/folder/${PREFIX}-DBNAME-db.sql.gz; zip -r /path/to/backup/folder/${PREFIX}-wordpress-files.zip /path/to/wordpress/wp-content/; zip -r /path/to/backup/folder/${PREFIX}-owncloud-files.zip /path/to/owncloud/data/;
• 0 23 * * * rm -r /path/to/backup/folder/*

A few notes for someone trying to copy this set-up

• Your web host might be in a different time zone, so you might need to keep that in mind when coordinating cron jobs on your web host with ones on a local machine.
• My web host provided a cron job editor that automatically escapes special characters like %, but you might have to add back-slashes to make yours work if you’re manually editing with crontab -e.
• You might want to put a .htaccess file in your backup directory with the following in it: “Options -Indexes” (remove the quotes of course). This stops other people from going to your backup directory in a browser and helping themselves to your files. You could also name your backup directory with a random hash of letters and numbers if you wanted to make it difficult for people to steal your backed-up data.

Local cron job

Then on the local machine, the old iMac, I set up the following cron job. It downloads the files and saves them to a folder on an external hard disc every day at 6h00.

• 0 6 * * * PREFIX=`date +%y-%m-%d`; curl http://www.your-web-site.com/back-up/${PREFIX}-DBNAME-db.sql.gz > /Volumes/External HD/Back-ups/${PREFIX}-DBNAME-db.sql.gz; curl http://www.your-web-site.com/back-up/${PREFIX}-wordpress-files.zip > /Volumes/External HD/Back-ups/${PREFIX}-wordpress-files.zip; curl http://www.your-web-site.com/back-up/${PREFIX}-owncloud-files.zip > /Volumes/External HD/Back-ups/${PREFIX}-owncloud-files.zip;

If you were super-paranoid about losing data, you could install this on multiple local machines, or you change the timing so that the cron jobs run twice a day, or as often as you liked, really. As long as they’re always turned on, connected to the internet and they have access to the folder where the backups will go, they should work fine.

Stoop-n-scoop

This isn’t a super-secure way to back up your files, but then we’re more worried about losing data accidentally than having it stolen maliciously. I don’t think the world of medical ethics is cut-throat enough that our academic rivals would stoop to stealing our data in an effort to scoop our papers before we can publish them. That said, I’m not about to give away the exact URL where our backups are stored, either.

The practical upshot of all this is that now we have at least three copies of any file we’re working on. There’s one on the computer being used to edit the document, there’s one stored remotely on our web host, and there’s a copy of all our files backed up once a day on the old iMac at the Medical Ethics Unit.