AWS AutoScaling, downscale - wait for processes termination

Question

I want to use AWS AutoScaling to scaledown a group of instances when SQS queue is short. These instances do some heavy work that sometimes requires 5-10 minutes to complete. And I want this work to be completed before the instance termination. I know a lot of people should have faced the same problem. Is it possible on EC2 to handle the AWS termination request and complete all my running processes before the instance is actually terminated? What is the best approach to this?

Accepted Answer

Assuming you are using linux, you can create a pre-baked AMI that you use in your Launch Config attached to your Auto Scaling Group.

In the AMI you can put a script under `/etc/init.d` say `/etc/init.d/servicesdown`. This script would execute anything that you need to shutdown which would be scripts under `/usr/share/services` for example.

Here's kind like the gist:

servicesdown

It would always get executed when doing a graceful shutdown.

Then say on Ubuntu/Debian you would do something like this to add it to your shutdown sequence:

```
/usr/sbin/update-rc.d servicesdown stop 25 0 1 6 .
```

On CentOS/RedHat you can use the `chkconfig` command to add it to the right shutdown runlevel.

AWS AutoScaling, downscale - wait for processes termination

Solution

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