The Official Scalr blog

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

We integrated phpmyadmin, a database administration tool, into Scalr today. It allows you to see the data you have on your database, update individual records, alter tables, and do lots of other stuff.

This is another step into making Scalr a great tool for sysadmin work, and making great sysadmin more accessible to non-specialists.

You can find it under Farms > View, and from options, select MySQL status. Click ‘Setup PHPMyAdmin access’, wait a minute, refresh, and you’re done!

Let us know what you think!

If you used Scalr.net these last few days, you probably experienced some mysql connection errors. These were due to a very large amount of concurrent connections, typically when a large farm (100+ instances) is launched, as it triggers too many requests too quickly, before Scalr can react to load.

This was more of an architectural flaw, so we worked to reduce the amount of requests every instance makes. In many cases we got it down to a single request. For example, when an instance requests a list of instances of a role, it now gets all the information for all roles in the single initial request. Same goes for the config_opts queries from instances, equally optimized (we brought down the amount of requests to rebuild /etc/aws/hosts from 5 requests to a single one).

The next thing we did is tune mysql to handle thousands of connections, and over 100 other settings and sysctl options, then optimized our db structure (incl. added new indexes).

We also moved some stuff higher up in the stack to nginx, to be served faster.

We took the occasion to rewrite the client dashboard so that logs load instantly. You’ll notice this when you first log in.

Bottom line is that things are faster for you, and put less load on us.

Hi all,

Amazon announced availability of a couple new features last week, one of which is the possibility of using Elastic Load Balancing for EC2 in the EU region.

This will interest those who have users in Europe and have created a farm in the EU region to reduce latency. They can now save on a dedicated instance serving as a load balancer, as Scalr has added support for it.

Cheers,
Sebastian

Last week we announced Scalr Mission Critical, a service that guaranties that someone will be there to help if your site goes down. It gives you phone support, IM support, and short response times when using support.scalr.net.

This week we are proud to announce Scalr Development, a free version of Scalr open for developing your application while you don’t need the scalability requirements of a Production environment. This edition is limited to subdomains of development.scalr.net, so you can use myapp.development.scalr.net, for example. When you are ready to launch, just use ApacheBench or Tsung to test reaction to massive load, then sign up for Scalr Production and you’ll be good to go.

We are only accepting a limited amount of users this week, so please be patient if you are not accepted immediately.

Cheers,
Sebastian, on behalf of the Scalr Team.

Last week we updated the dashboard to include logs and shortcuts, today we released a new menu bar. If you haven’t done so already, log in, check it out, and let us know if you have any suggestions for improvements.

Stay tuned for much more beginning next week!

We’re pleased to release the first beta of Scalr Remote, a web-based application that uses Scalr’s API to let you check in on your applications and farms – load, size, and health – and show it to friends or colleagues. And if anything needs to be done, you can even use it to manage your infrastructure!

It is available at mobile.scalr.net, and will soon be integrated into scalr.net so when you click on an email alert, you’ll be taken to the proper UI.

To add the Scalr Remote Control to the home screen of your iPhone (see below), click the + icon and ‘Add to Home Screen’. Give it a name and your done!