Bob the Scheduler

Bob the Scheduler is program used to schedule tasks. It plays nicely with Docker (or any other containers) and integrates with file-based configurations.

Bob's mission is to provide application developers a convenient way to schedule repeating jobs. It is intended to be run as PID 1 in container and spawn jobs.

If you need more advanced tasks like running tasks in other container, check Ofelia or K8S cronjobs.

How to use

Create directory /etc/bob-the-scheduler/tasks with jobs described as YAML files The job description should be saved with .yml or .yaml extension.

# task-01.yaml
task_name:  task-01
schedule: "@daily"
command: touch /var/data/timestamp
enabled: no

save_output: on-failure,on-success

# generate-images.yml
task_name: update-images
schedule: "CRON_TZ=Europe/Bratislava 12 01-07 * * *"
command: php /usr/local/www/cronjobs/update-images.php

How to start

bob-the-scheduler -c /etc/bob-the-scheduler -o /var/spool/bob-the-scheduler/ -p 8080 -v

Bob will periodically check new files in the config directory a and schedule its job.

Used command line parameters

• -c says where the tasks directory with YAML files is located,
• -o where to save the jobs output.
• -p provides healthcheck endpoint on http://localhost:8000/healhtz
• -v increase verbosity

The scheduling is done in UTC, but you can use CRON_TZ syntax to schedule in any other zone.

All the jobs are started with UID/GID of the calling user.

Job run

• When the job is going to be started, Bob creates /var/spool/bob-the-scheduler/task-name/ directory.
• The job will get timestamp.
• Bob will create/overwrite file /task-name/last-start containing timestamp
• It will create /task-name/stdout-timestamp.running file and redirects job command stdout there.
• Jobs stderr is not going to be redirected
• After successfull run, file /task-name/last-success is created/overwritten (containing timestamp)
• After successfull run stdout file is moved to stdout-timestamp.succeeded
• After failed run, file /task-name/last-failure is created/overwritten (containing timestamp)
• After failed run stdout file is moved to stdout-timestamp.failed

Job parameters

• task_name: ob name to use in file names. Defaults to job file name without
• schedule: (required). Job schedule according to robfig's cron. Re
• command: (required). Command to run
• enabled: should the job be run? Defaults to True.
• save_output: Should we keep the job output on success or failure? Default on-success,on-failure

What Bob does not do?

• Mail reports on failures.
• Enforce resource constraints (CPU/memory).
• Report tasks' state through HTTP API.
• Change UID/GID on execution.
• Cleanup its files.

Patches are welcome.