dron – simple frontend for Systemd, inspired by cron.

• d stands for ‘Systemd’
• ron stands for ‘cron’

dron is my attempt to overcome things that make working with Systemd tedious

What does it do?

In short, you type dron edit and edit your config file, similarly to crontab -e:

from dron.api import job

:

# at the moment you're expected to define jobs() function that yields jobs
# in the future I might add more mechanisms
def jobs():
    # simple job that doesn't do much
    yield job(
        'daily',
        '/home/user/scripts/run-borg /home/user',
        unit_name='borg-backup-home',
    )

:

    yield job(
        'daily',
        'linkchecker https://beepb00p.xyz',
        unit_name='linkchecker-beepb00p',
    )

:

    # drontab is simply python code!
    # so if you're annoyed by having to rememver Systemd syntax, you can use a helper function
    def every(*, mins: int) -> str:
        return f'*:0/{mins}'

:

    # make sure my website is alive, it will send local email on failure
    yield job(
        every(mins=10),
        'ping https://beepb00p.xyz',
        unit_name='ping-beepb00p',
    )

After you save your changes and exit the editor, your drontab is checked for syntax and applied

• if checks have passed, your jobs are mapped onto Systemd units and started up
• if there are potential errors, you are prompted to fix them before retrying

Why?

In short, because I want to benefit from the heavy lifting that Systemd does: timeouts, resource management, restart policies, powerful scheduling specs and logging, while not having to manually manipulate numerous unit files and restart the daemon all over.

I elaborate on what led me to implement it and motivation here. Also:

• why not just use cron?
• why not just use systemd?

Setting up

1. install system dependencies (see .ci/run ) – these are necessary for dbus-python library
2. install dron: pip3 install --user git+https://github.com/karlicoss/dron
3. install sendmail from your package manager if you want to recieve job failure emails

Using

usage: [-h] [--marker MARKER] {monitor,past,edit,apply,lint,uninstall} ...

dron -- simple frontend for Systemd, inspired by cron.

- *d* stands for 'Systemd'
- *ron* stands for 'cron'

dron is my attempt to overcome things that make working with Systemd tedious

positional arguments:
  {monitor,past,edit,apply,lint,uninstall}
    monitor             Monitor services/timers managed by dron
    past                List past job runs
    edit                Edit  drontab (like 'crontab -e')
    apply               Apply drontab (like 'crontab' with no args)
    lint                Check drontab (no 'crontab' alternative, sadly!)
    uninstall           Uninstall all managed jobs

options:
  -h, --help            show this help message and exit
  --marker MARKER       Use custom marker instead of default `(MANAGED BY DRON)`. Possibly useful for developing/testing.

Job syntax

The idea is that it’s a simple python DSL that lets you define simple jobs with minimal friction.

However, if you wish you can pass arbitrary unit properties as keyword arguments as well.

Caveats

• older systemd versions would only accept absolute path for ExecStart. That should be caught during dron edit though

Potential improvements

• custom validation; at the moment it runs pylint, mypy and systemd verify
• make it more atomic?

  E.g. roll back all the changes until daemon-reload

• more failure report mechanisms?

  Ideally, benefit from ntfy

add issues with various questions that I had in code?