hartwork / pytocron

Container cron with seconds resolution

pytocron

pytocron is a cron implementation targeting containers, written in Python, with seconds and year resolution, native support for Healthchecks.io and >90% test coverage. It is licensed under GNU Affero General Public License v3.0 or later and is meant to remain simple and maintainable.

One particular prime use case is to feed uptime monitoring. For example, here is how I monitor availability of my blog:

# hc-ping: https://hc-ping.com/00000000-0000-0000-0000-000000000000
*/30 * * * * * * wget -qO- -T2 https://blog.hartwork.org/ | grep -qF 'Hartwork Blog'

This would make pytocron check the blog for availability every 30 seconds and ping Healthchecks.io with the resulting exit code because of the # hc-ping: <URL> comment line.

Regarding name "pytocron": It was inspired by the term pytosquatting and it had no search results on Google.

If you like pytocron, please support it with a star!

Installation

# pip3 install pytocron

or

# pipx install pytocron

Usage

# pytocron --help
usage:
  pytocron [OPTIONS] CRONTAB
  pytocron --help
  pytocron --version

Container cron with seconds resolution

positional arguments:
  CRONTAB               Path to crontab file

options:
  -h, --help            show this help message and exit
  --log-level {DEBUG,ERROR,INFO}
                        Logging level (default: INFO)
  --pretend             Do not actually run commands (default: do run commands)
  --version             show program's version number and exit

environment variables:
  NO_COLOR              Disable use of color (default: auto-detect)
  SENTRY_DSN            Sentry [d]ata [s]ource [n]ame URL
  SENTRY_ENVIRONMENT    Sentry Environment (default: "production")
  SENTRY_RELEASE        Version or Git SHA1 to use with Sentry

Software libre licensed under AGPL v3 or later.
Brought to you by Sebastian Pipping <[e-mail]>.

Please report bugs at https://github.com/hartwork/pytocron/issues — thank you!

# pytocron --log-level ERROR <(echo '*/2 * * * * * * LC_TIME=C date')  # syntax needs Bash
Thu May 15 02:36:06 CEST 2025
Thu May 15 02:36:08 CEST 2025
Thu May 15 02:36:10 CEST 2025
^C

Comparison with other crons

	pytocron	Supercronic	Vixie Cron
Written in	Python	Go	C
Container support
∟ Targets	containers	containers	non-container systems
∟ Environment variables	kept	kept	?
∟ Multi-user mode	✘	✘	✔
∟ Logging target	stdout, stderr	stdout, stderr	syslog or log file
∟ Log rotation support	✘	✔	✔
∟ Command shell	bash -e -u	/bin/sh	/bin/sh
∟ Daemonization	✘	✘	✔
∟ Crontab reloading	✘	✔	✔
Integrations
∟ Support for Healthchecks.io	✔	✘	✘
∟ Support for Sentry	✔	✔	✘
Crontab syntax
∟ Seconds and year resolution	✔ (forced)	✔ (optional)	✘
∟ Implementation	croniter	cronexpr	custom
Exceeded job runtime handling	auto-kill	overlapping or skips	?
Handling of daylight saving time	skips, duplicates	?	?
Reaction to NTP adjustments	none	?	?
Signal handling
∟ SIGHUP	shutdown	shutdown	log file reopen
∟ SIGUSR2	shutdown	crontab file reload	shutdown

Contributing

Prior to opening pull requests, please create an issue to discuss the matter first. Thank you!

Security

If you believe to have found a security issue within pytocron, please reach out via e-mail. Thank you!

Support

Please report any bugs that you find.

Like this tool? Support it with a star!