How can I tell if CPUUtilization in AWS is the reason my website sign-up is timing out?

Question

Our website is hosted on AWS in a t2.small instance. User-facing sign-up is currently timing out.

Initially, I was getting a loadbalancer latency alarm notification for this instance, so I increased the limit, which seemed to work as a temporary solution.

However, once I increased the limit, I started getting 2 other alarm notifications, which were as follows:

1) production-remove-capacity-alarm

Description: None

Threshold: CPUUtilization <= 40 for 3 datapoints within 15 minutes

2) AWSEBCloudwatchAlarmLow

Description: ElasticBeanstalk Default Scale Down alarm

Threshold: NetworkOut < 2,000,000 for 1 datapoints within 5 minutes

It seems to me that I should simply change the alarm notifications so that I'm no longer alerted to #2, as I don't see how this is interfering with anything, but please correct me if I seem to be missing something.

Regarding #1, does it seem likely that somehow adjusting CPU Utilization in AWS will solve the timeout issue with website sign-up?

And if so, what specifically ought to be done?

Answer 1

Everything is okay. Don't panic.

The first priority is that your application operates correctly. Hopefully your adjustment to the instance type ) satisfactorily fixed this (but it is still worth watching).

The above two alarms are basically saying:

• CPU is under 40%
• There's not a lot of network traffic

These alarms can be used to scale-in instances (reduce the number of instances) so that you are not paying for excess capacity. There would be similar alarms that let you scale-out (add additional instances).

ALARM simply means the check is True . That is, the condition has been satisfied. It does not necessarily indicate a problem.

I'm going to presume that you currently have only one instance running. If so, you can ignore those alarms (and Auto Scaling will ignore them too) because you are already at the minimum capacity.

If Auto Scaling has been configured to scale-out to more instances, these alarms would later scale-in to save you money. They're probably a bit trigger-happy, only looking at 15 minutes CPU and 5 minutes of network traffic — it would normally be better to wait for a longer period before deciding to remove capacity.

Bottom line: If your application is running correctly and you are only operating a single instance, there's nothing to worry about. It's all working as expected.