A billing gotcha with AWS Workspaces and Directory Service

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July 17, 2021

My personal Amazon AWS bill has been unusually high for the past few months, so I broke open the cost explorer to see where the money was going.

AWS Costs

Almost of it was expected - EC2 instances, domain registration and renewal, and so forth. Some was due to laziness (hadn’t gotten around to purchasing reserved instances for my EC2-based servers).

But one of the costs was completely unexpected: a Directory Service cost that appeared in November 2020, and has totalled AUD281.77 since then.

A quick online chat with AWS support provided the explanation: when I created an AWS Workspace back in 2019, a Directory Service resource - a Directory - was automagically created for me. That Directory was free as long as I had a Workspace.

However in November 2020, I deleted the Workspace. That did not destroy the Directory, at which point I started being charged for it, to the tune of around AUD35 per month.

Amazon is being very good about it, and winding back all of the Directory Service charges since 2020. It’s reassuring to know that I’m not being billed for what I see as a UX bug :)

But this is an anti-pattern I haven’t seen until now: destroying a resource caused me to start being billed for another. Something to keep an eye open for in the future :)