Today Scalr released the Scheduler, a Cron Job task manager designed for Cloud environments.
The problem is that Cron jobs, which are scripts that are executed periodically, were up until now tied to individual servers. When that individual server failed, the Cron job wouldn’t be executed. When that server was scaled, it would be executed once per server. This means that the tasks you set to be executed once per hour, could be executed 5 times in the hour, or not at all – not very reliable, to say the least.
Scalr based the Scheduler off Apache ZooKeeper, which is a part of Hadoop. It is a centralized service for providing group services, especially distributed lock services. The Scheduler extends Scalr’s scripting interface, and allows you to write scripts and set their execution schedule and scope: once on all servers, every hour on a subset of servers, daily on a single server, and any other combination!
As always, the code is available on Google Code and delivered as a service at scalr.net.
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You can find the Scheduler under the Tools menu, found at the top when logged in:
You can schedule tasks to be executed periodically using the Scalr Scheduler
To add a Cron job or schedule a script, click the + icon next to the Search box:
Click the + icon to add a new cron job or to set a schedule for a script
You can then select the script to be executed, choose the parameters for it, schedule a time or interval, and run!
Configure the cron job's interval, parameters, and more