systemd-timer backend

Layout

Per (app, job, schedule-index), cronix manages a pair of unit files:

/etc/systemd/system/cronix-<app>-<job>-<idx>.timer
/etc/systemd/system/cronix-<app>-<job>-<idx>.service

The .timer carries OnCalendar=; the .service invokes cronix trigger <app>.<job> once. Both files include X-Cronix-{App,Job,Index,Hash}= annotations cronix uses for ownership detection (systemd ignores X- prefixed fields, so they double as our marker).

Reconciling a manifest

sudo cronix apply \
  --manifest /etc/cronix/manifest.json \
  --backend systemd-timer \
  --trigger-bin /usr/local/bin/cronix

Add --systemd-unit-dir <path> to install into a non-default directory (useful for user-scoped units under ~/.config/systemd/user/). cronix will refuse to run if /run/systemd/system doesn’t exist (i.e. systemd isn’t the init system).

cronix list, cronix plan, cronix drift, cronix prune, and cronix show all accept the same backend flags.

Rendering by hand

import "github.com/awbx/cronix/go/internal/backends/systemd"

timerFile, serviceFile, err := systemd.RenderUnits(
    "/usr/local/bin/cronix",
    "billing",
    job,         // a manifest.NormalizedJob
    0,           // schedule index
)
// Write to /etc/systemd/system/cronix-billing-<jobname>-0.{timer,service}

sudo systemctl daemon-reload
sudo systemctl enable --now cronix-billing-<jobname>-0.timer

OnCalendar translation

Manifest schedule	Rendered `OnCalendar=`
`@hourly`	`hourly`
`@daily` / `@midnight`	`daily`
`@weekly`	`weekly`
`@monthly`	`monthly`
`@yearly` / `@annually`	`yearly`
`0 2 * * *`	`--* 2:0:00`
`0 9 * * 1-5`	`Mon..Fri --* 9:0:00`

Run systemd-analyze calendar "<expr>" to verify a translated expression in your systemd version.

Run history

journalctl -u cronix-billing-<jobname>-0.service --output=json --since=24h

The shim emits one structured JSON line per fire to stdout, so each entry’s MESSAGE field is a self-describing record.

Limitations

Sub-minute scheduling is supported by systemd but rejected at v1’s manifest validation layer for fidelity with crontab. May relax in a later version for systemd-timer-only deployments.
Replace concurrency policy is enforced by the shim, not by RuntimeMaxSec=.