We get asked a lot of questions on Scalarium, so we thought we'd compile the most important of them into an FAQ for you to enjoy. If you have more questions, don't hesitate to get in touch!

What cloud infrastructure do you support?

Right now we're supporting Amazon's EC2, simply because it has the best feature set and API out there.

Can I manage my already running EC2 instances?

As Scalarium is not a generic EC2 management solution, the answer is no. We're provisioning the instances with a client that communicates with our service. Since this bootstrapping is done using EC2's user data and happens once on boot, it's next to impossible to provision an instance with our software after it's already been booted through some other means.

Are the instances you're managing on my behalf mine to keep?

We're using your AWS credentials to manage your infrastructure, so we're running them on your behalf. You'll have full root access to your instances. Should you decide to not use Scalarium anymore, we won't kill your instances, they're still yours to keep and use.

Do you support Reserved Instances?

If you bought a reserved instance through Amazon, it'll be automatically applied to either an already running instance of the corresponding type or applied when you start the next instance.

Which EC2 datacenters do you support?

Right now we're focussing on eu-west, which is located in Ireland. We do have plans to support any region available on EC2 in the future.

Which application stacks do you support?

Our default stacks are Rails/Rack using Passenger running on Ruby Enterprise Edition and PHP using mod_php and Apache. Most of the work configuring them is done using Chef, so if you have a particular need, let us know, and we'll look into it. If all you want is to deploy some static files onto a web server, that's cool too, we got you covered.

We don't support Rails 3 yet.

Which database is the default?

You guessed it, it's MySQL. However, that's just our default. We foster a culture of alternative databases ourselves, so we'll definitely throw in PostgreSQL soon. In the meantime, you're free to roll your own Chef cookbooks to add in any database you wish. We started with a simple Redis installation, and will add CouchDB soon.

My application's deployment is a bit more complex than the average!

No problem. We're deploying your code using Chef's Deploy resource. You can include a couple of Ruby files in your application's code base that will be executed depending on the stage of deployment. There's four hooks available for you: before restart, before migrate, before symlink, after restart. If that's still not enough for you, you can provide Scalarium with a bunch of cookbooks which we're happy to run after we're done with our part of the development. We'll provide more documentation on this soon.

Can I use my own AMIs?

No, not so far at least. We're using a vanilla Ubuntu 9.10 image with some updates installed to speed up the initial boot process. Other than that we're provisioning the instances solely from scratch depending on their role in the cloud.

Can I monitor my instances using Scalarium?

We have some basic monitoring on Scalarium, including CPU, load average and memory, parameters on which we auto-scale your cloud, but so far we're not planning to offer a full monitoring solution a la Nagios or Munin with full alerting etc. We will however make it easy to set up one of them on your instances.

Can you automatically scale my database?

We're afraid we don't have any magic pixie dust we can sprinkle on your database so that it's really, really fast. We can only configure it to the best of our knowledge, take snapshots of it, and maybe set up the occasional slave for you. We can't, however, automatically detect bottlenecks in your application, which includes your database. We're glad to help you out with problems, but we think that trying to automatically scale a database by adding more and more slaves or even (gasp!) a master-master replication setup, is a bad idea.

Where the heck is my beta invite?

We're slowly opening up Scalarium for users, because at least at the moment, we want to make sure that we get good and valuable feedback while still having the option to change things without affecting too many users. We already have production sites running on Scalarium, so rest assured that we're getting there, just slowly. If you feel like you definitely deserve an invite, please let us know, and we'll see what we can do.