Interestingly, I tweeted this post about the free tier trap a few days ago. Last week I ran into something relatable.
I created a new AWS account a few weeks ago to run a WordPress blog. My intention was to keep it entirely on the free tier as I did not want to attach my card and I didn’t expect much traffic in first few months. All this account had was an EC2 instance (t2.micro) and an EBS volume (30GB). After running this for a few weeks, I noticed a charge of $0.01 being there on the billing console. Since AWS cost optimisation is my area of interest, I decided to go deep into this rabbit hole and get to the root of this.
Exploring the cost explorer
I started out with the cost explorer to find out the reason for this charge. On the service level, this $0.01 charge was attributed to the infamously vague category of “EC2-Other”. This category can include anything from an EBS volume to a public IP address to anything else in between.
Grouping the data by charge type
Grouping the data by “Charge Type” revealed that the charge was categorised under “usage”.
Since this is pretty vague, I searched AWS docs for the definition and this is what I found.
What this roughly means is that this charge is not due to tax, credits, some reservation or savings plan or even support fee. This is due to some actual usage of a service. Again, very vague.
Grouping the data by usage type
Grouping the data by “Usage Type” revealed that the charge was categorised under “others”. See the below screenshot. We can now effectively rule out any data transfer out charges.
Customer support helped..a bit..
Confused and intrigued, I headed out to raise a support ticket. The automated resolution tried to show some possible reasons for this. See below screenshot.
I went ahead and filed the ticket anyways.
After multiple followups, with the customer support team, they figured out the exact cause of this. It was due to regional data transfer.
Regional Data Transfer: This is data being transferred from a resource in one region to another region.
I am however using a single t2.micro instance with a small 30GB EBS volume attached to it.
While customer support helped in debugging this, they could not help further and could not provide more detailed logs.
Wrapping Up
Cost explorer, Reddit, slack communities and even AWS customer support team could not help me with a definitive root cause for this charge. All I know is that this is due to some data transfer that doesn’t come under the free tier. I feel that this is due to some AWS’ internal housekeeping stuff. However, I do not yet have a clear answer.