infracamp/mrcron repository overview

⁠Mr. Cron: Cloud Cron Scheduler

Cloud ready cron scheduler service. Mr. Cron will scrape multiple urls for cronjob data and execute (call desired urls). No additional services are needed.

Features:

• No database / persistence needed
• No complex configuration
• Handles up to 500 Cron Requests in parallel
• Services define their own jobs (secret job-tokens can be applied)
• UDP Syslog aware logging interface
• Compatible to wildly used crontab⁠ format

⁠Installation / Running MrCron

Just run the publicly available docker image from DockerHub⁠:

docker run -e "CONF_SCRAPE_URLS=http://xy/mrcron.json" infracamp/mrcron

• Demo docker-compose.yml⁠: Compose file to deploy MrCron directly to docker-swarm stack.
• Demo kubernetes service.yml⁠: Deploy on kubernetes
• Demo mrcron-jobs.json⁠: This file can be added to every service that has cronjobs to run

⁠Configuration

⁠Environment

CONF_SCRAPE_URLS

The urls to scrape for jobdef.json content. Multiple URLs can be specified separated by semicolon.

⁠MrCron jobdef.json

{
  "jobs": [
    {
      "id": "Unique job identifier",
      "cron": "<cron timing def>",
      "urls": [
        "http://some.tld/to/call"  
      ]   
    },
    ..next job..
  ]
}

⁠Cron timing def

* * * * *
┬ ┬ ┬ ┬ ┬
│ │ │ │ │
│ │ │ │ └──── Weekday (0-7, Sunday is 0)
│ │ │ └────── Month (1-12)
│ │ └──────── Day (1-31)
│ └────────── Hour (0-23)
└──────────── Minute (0-59)

Examples

* * * * *: Run the job each minute

0 * * * *: Will run the job once per hour at xx:00

0 0 * * *: Run the job daily at Midnight (00:00)

0 0 1 * *: Run the job on Midnight (00:00) on first day of the month

0 0 * * 0: Run the job on Midnight (00:00) on each Sunday (0 => Sunday)