Hey, it's Ereb

Basically, it's easy installable cron with web interface. Just pip3 install ereb && ereb and open localhost:8888 Ereb is not based on system crond, it works with own scheduler written using Tornado. It has:

• JSON API
• stderr, stdout of each task run
• historical data about slowest and most failing tasks
• no memory leaks (hope so, but uptime >months without memory leak is normal)
• crond syntax
• Slack notifications
• Tyler The Creator as a logo

And the best thing about ereb: it really works and made already thousands task runs on our servers.

How to install

pip3 install ereb

Generic task run

It is possible to run generic command without creating new task. POST requiest to generic_tasks/run with name, cmd and timeout params. Example:

curl -v -X POST 'http://localhost:8888/generic_tasks/run' -d '{"name": "foo", "cmd": "echo bar", "timeout": 60 }'

After that in Ereb new task with name __generic_foo will start

JSON api

get /status => info about next runs get /tasks => tasks list get /tasks/foo => extended info about foo task with recent task runs post /tasks/foo => update foo task config get /tasks/foo/task_runs/%id% => get task run %id% info for foo task get /tasks/foo/run => manual run of foo task get /tasks/foo/shutdown => kill currenly running foo task

Development

Backend development

First you do pip3 install -r requirements.txt

then

python3 ereb/erebd.py

UI development

For js app building you need webpack (and nodejs of course) You can use webpack-dev-server, so

cd ereb/ereb-wi
npm install
npm install -g webpack
npm install -g webpack-dev-server

webpack-dev-server

And your live-reloadable app will be served on localhost:8080

After work done, you have to make production build with cd ereb/ereb-wi && webpack -p and commit changes to repo :)

Migration from crontab

Use utility crontab_converter.py

crontan -l | python3 crontab_converter.py --output_dir=./etc

to generate tasks from your crontab file. Important! Check new tasks after that!

Task config example

{
  "cmd": "while :; do echo 'Hit CTRL+C'; sleep 1; done",
  "cron_schedule": "* * * * *",
  "description": "",
  "enabled": true,
  "group": "",
  "timeout": 10,
  "name": "infinite_loop",
  "shell_scripts": [],
  "task_id": "infinite_loop"
}

Notifications

To turn on notifications

cp notifier.json.example notifier.json

and make proper shell commands. Token %s in config will be replaced with your real error message.

Then use --notify-to parameter for running ereb.py, for example to use slack do:

python3 ereb.py --notify-to=slack

Clean history

rm -rf var/

Monit

Example monit config (for ereb installed via pip)

check process ereb pidfile /PATH/TO/EREB/tmp/ereb.pid
    start program = "ereb & echo $! > /PATH/TO/EREB/tmp/ereb.pid"
    stop program = "/bin/bash -c '/bin/kill `cat /PATH/TO/EREB/tmp/ereb.pid`'" with timeout 65 seconds
    group system

Troubleshooting

My web interface stopped responding

This may happen if you have a big number of tasks and/or their schedule is quite frequent. In this case history storage's task_runs table (we have sqlite3 database) gets pretty big after a while and causes task scheduler component to block the web interface's i/o loop.

There is an issue already opened up about this problem, but until it is resolved you can try cleaning up your task_runs table.

To clean up all history data for task runs older than a month, simply log into sqlite3 (assuming your database file has a standard var/ereb.db location):

sqlite3 var/ereb.db

and run a DELETE command:

DELETE FROM task_runs WHERE started_at < datetime('now', '-1 month');