Autoscaling for Digital Ocean?

Sounds like a fun project (and totally doable)! :)

If I were you, I'd make heavy use of ansible, or something similar, for provisioning:

1) folks are familiar with it 2) could make it cross-platform more easily 3) well, no reinventing the wheel.

For example, Ansible has ec2 module http://docs.ansible.com/ansible/ec2_module.html where you describe an instance and the number of them that should be running. So if you have 3 instances running and wish to have 5, it does the magic and spins up new ones. Then, you can add them to a load balancer. Maybe there's something similar for DO already?

The way I see it is that it would poll if scaling conditions are met and execute ansible playbooks if they are, and then some web interface to set the conditions / view the scaling logs / current status.

It can turn out to be a very entertaining and educational side project :)

If you decide to do it, drop me an email - something I would be happy to brainstorm and discuss about :)

EDIT: It could also be used not only for autoscaling but also for self-healing. If some instance crashed and is not responding anymore, then spin up a new one.

"AWS costs almost twice more than analogous DO servers, but AWS has way more features."

When you us AWS you are paying for more than just a cheap VPS, which essentially is all DO is. It's comparing fast food to a fancy steak house. You can get meat at both, but at one side its microwaved. Not to say DO isn't great, it gets the job done and provides a valued service, but your money gets you what your money gets you.

The only DO-specific bit would be DO API to create/delete droplets (VPS) so that shouldn't be hard at all :)

I would pay for this - email in my profile, let me know when you launch.

At clanofthecloud.com (Gaming backend as a service), we needed to implement autoscaling for DO, in node.js. We used consul.io for service discovery. CPU load was used as the central metric, and each service instance would store it in consul.io. We then triggered the creation/destruction of instances with thresholds.

In the end, we only used it for our sandbox environment, as the production env runs on bare metal (more capacity, cheaper at scale, easier on admin).

So I'd say, from our experience:

- DO's API was quite easy to work with

- consul.io was used as a reliable distributed source of information, for leader elections and health monitoring... Changing the autoscaler configuration in consul.io produced immediate results like starting/stopping new instances... Cool "remote control" effect ;-)

- haproxy/nginx load balancers use consul.io templates to update their configuration

- our autoscaler was HA, through a leader election. The instances managed themselves (no single point of failure). There were at least 2 instances running.

- you should expect a few "surprises" if you're running consul.io on Digital Ocean, heartbeats are delayed quite often (depends on datacenters), which makes failure detection hard

- and of course, we used DO custom images to start new instances