[Klathmon]

I always loved a similar idea that I believe Google uses (or used at one point) for sunsetting APIs.

You start by making 1% of requests fail on the scheduled date, then gradually increase that percentage over time until 100% of requests are failing.

This gives anyone that doesn't follow your blog or news to start realizing that there's a problem and find a solution before it completely cuts off.

I personally feel a brownout of 1 hour will barely register as a blip at many places, and if it goes back to working 100% they are liable to just ignore it after it resolves itself.

[myelin]

Last time we deprecated something in App Engine, we made an "opt out" flag, that customers could manually flip to keep the old way working for another week. This was reset every 7 days, until the final switchoff date. This worked pretty well; we saw fewer and fewer customers opting out as everyone updated their code, and the final deadline didn't come as a surprise to anyone.