Pro Tip: You Can Scale AWS ASGs Down to Zero

It sounds obvious when you first say it: you can scale AWS ASGs (Auto Scaling Groups) down to zero. This can be a cost-savings measure: zero servers means zero cost. But most people do not do this!

Wait — Why Would You Want to?

Maybe you’ve heard the DevOps saying: servers should be cattle, not pets. This outlook would say that you should have no single server that is indispensable — a special “pet”. Instead, servers should be completely replaceable and important only in herd format, like cattle. One way to adhere to this framework is by creating all servers in groups.

Some of our customers follow this principle: they use Auto Scaling Groups for everything. When they create a new app, they create a new ASG — even if it has a server size of one. This can remove challenges to scale up in the future. However, this leaves these users with built-in wasted spend.

Here’s a common scenario: a production environment is built with Auto Scaling Groups of EC2 instances and RDS databases. A developer or QA specialist copies production to their testing or staging environment, and soon enough, there are three or four environments of ASGs with huge servers and databases mimicking production, all running, and costing money, when no one is using them.

By setting an on/off schedule on your Auto Scaling Groups, you can scale them down to a min/max/desired number of instances as “0” overnight, on weekends, or whenever else these groups are not needed.

In essence, this is just like parking a single EC2 instance when not in use. Even for an EC2 instance, users are unlikely to go into the AWS console at the end of a workday to turn off their non-production servers overnight. For ASGs, it’s even less likely. For a single right-click to stop an EC2 instance, an AWS ASG requires you to go to ASG settings, edit, modify the min/max/desired number of instances — and then remember to do the opposite when you need to turn them back on.

How You Can “Scale to Zero” in Practice

One ParkMyCloud customer, Workfront, is using this daily to keep costs in check. Here’s how Rob Weaver described it in a recent interview with Corey Quinn:

Scaling environments are a perfect example. If we left scaling up the entire time — 24/7 — it would cost as much as a production instance. It’s a full set of databases, application servers, everything. For that one, we’ve got it set so the QA engineers push a button [in ParkMyCloud], they start it up. For a certain amount of time before it shuts back down.

In other cases, we’ve got people who go in and use the [ParkMyCloud] UI, push the little toggle that says “turn this on”, choose how long to turn it on, and they’re done.

How else does Workfront apply ParkMyCloud’s automation to reduce costs for a 5X ROI? Find out here.

Another Fun Fact About AWS ASGs

One gripe some users have about Auto Scaling Groups is that they terminate resources when scaling down (one could argue that those users are pro-pet, anti-cattle, but I digress). If your needs require servers in AWS ASGs to be temporarily stopped instead of terminated, ParkMyCloud can do that too, with the “Suspend ASG Processes” option when parking a scale group. This will suspend the automation of an ASG and stop the servers without terminating them, and reverse this process when the ASG is being “unparked”.

Try both scaling to zero and suspending ASGs — start a free trial of ParkMyCloud to try it out.

Originally published at www.parkmycloud.com on September 17, 2020.