Building a better way to manage Koha LMS cron jobs

You know that sinking feeling when you’re SSH’d into a production server at 11 PM, carefully editing a crontab file, and you suddenly wonder: “Wait, did I save the backup?” Yeah, I’ve been there. Too many times.

Or, you’re a Koha librarian and you’d really like to know when that report’s meant to run or the emails are going to be sent.. Or even asked “Can I add a new task please”?

That’s why I built the Koha Crontab Plugin, because managing scheduled jobs shouldn’t require server access, terminal anxiety, and a good memory for cron syntax.

The problem that kept bugging me

Here’s the thing: Koha runs on cron jobs. Reports, cleanups, imports, exports – they’re all scheduled tasks. But managing them? That traditionally meant:

• SSH access to your server (which most library staff shouldn’t have)
• Editing text files in vi or nano (remember which one you prefer!)
• Remembering whether 0 * * * * means “every hour” or “at midnight” (it’s every hour, by the way)
• No undo button when you accidentally delete that critical line
• Zero visibility into what’s actually running.

For most libraries, this creates a bottleneck. Every little scheduling change requires a ticket. Want to adjust when your nightly report runs? Wait for your sysadmin. Need to temporarily disable a job? Hope someone’s available.

I kept thinking: there has to be a better way.

The “Aha!” moment

The solution hit me while reviewing someone else’s crontab that had about 50 different entries scattered everywhere with cryptic one-liners and zero documentation. What if we could manage the crontab file itself, but through a friendly web interface?

So I built a plugin that:

1. Manages your actual crontab file directly (using Config::Crontab)
2. Adds structured metadata to each job via comments
3. Provides a web interface where you can see all your jobs in one place
4. Lets you create, edit, enable/disable jobs without SSH access.

The jobs run through your normal cron daemon – nothing fancy, no extra layers. But now you get a nice UI, descriptive names, and the ability to manage everything without editing text files in a terminal.

What I built

The web interface you actually want

No more terminal required! We built a straightforward staff interface where you can:

• Create new scheduled jobs with descriptive names (not cryptic one-liners)
• Edit existing jobs without fear
• Enable or disable jobs with a click (no need to delete and recreate)
• See all your jobs in one place with their schedules and status
• Export everything to JSON for backup.

Rich job metadata

One thing that always frustrated me about traditional crontabs: zero metadata. You’d find an entry like 0 2 * * * /usr/local/bin/mystery_script.pl and spend 20 minutes figuring out what it does.

So I added structured metadata via comments:

• Job names: “Nightly patron import” beats “cronjob #7”
• Descriptions: Leave notes for future-you (or your colleagues)
• Environment variables: Each job gets its own environment config
• Timestamps: See when jobs were created and last modified
• Unique IDs: Every job gets a UUID for reliable tracking.

The plugin inserts these as special comment lines above each cron entry, so your jobs are self-documenting while remaining standard cron format.

Backup & restore

One-click export of all your job configurations to JSON. Perfect for documentation, disaster recovery, or just peace of mind.

Getting it running

Installation Steps

1. Grab the latest .kpz file from the releases
2. Head to your Koha staff interface: Administration → Plugins → Upload plugin
3. Upload and enable it.

The plugin handles the rest:

• Creates backup directory for crontab safety
• Initialises a template crontab if you don’t have one
• Sets up the web interface for job management.

Pretty straightforward, right?

⚠️ Security: Please read this part!

Okay, this is important, so I’m going to be direct: this plugin executes shell commands with your Koha instance user’s permissions. That’s powerful, but it also means you need to lock it down properly.

Before you let anyone create jobs, you must configure security.

Step 1: Set up the user allowlist

You have two options here, the service provider way using the koha-conf.xml file in the server: 

Edit your koha-conf.xml and add this to the <config> block:

<koha_plugin_crontab_user_allowlist>1,2,3</koha_plugin_crontab_user_allowlist>

Replace those numbers with the borrowernumbers of staff who should have access. Keep this list small – only people who understand the implications of running arbitrary commands on your server.

Alternatively, a superlibrarian can create a list from the plugin admin page to allow non-superlibrarians some limited access to the plugin.

This is not optional. Seriously.

Step 2: Establish which Koha scripts your users should be able to work with

The plugin admin allows you to define the subset of Koha scripts you would like to give your above selected staff to add and edit.

Step 3: Establish best practices

Make sure anyone with access knows:

• Review commands before enabling: Better safe than sorry, the script docs are now available right from the plugin!
• Be cautious with environment variables: They can change command behaviour in unexpected ways
• This is for experienced staff-only: With great power comes great responsibility!

 
I built in the allowlist feature specifically because I’ve seen what happens when command execution isn’t properly restricted. Don’t skip this step.