Building Waiting Room on Workers and Durable Objects
In January, we announced the Cloudflare Waiting Room, which has been available to select customers through Project Fair Shot to help COVID-19 vaccination web applications handle demand. Back then, we mentioned that our system was built on top of Cloudflare Workers and the then brand new Durable Objects. In the coming days, we are making Waiting Room available to customers on our Business and Enterprise plans. As we are expanding availability, we are taking this opportunity to share how we came up with this design.
You may have seen lines of people queueing in front of stores or other buildings during sales for a new sneaker or phone. That is because stores have restrictions on how many people can be inside at the same time. Every store has its own limit based on the size of the building and other factors. If more people want to get inside than the store can hold, there will be too many people in the store.
The same situation applies to web applications. When you build a web application, you have to budget for the infrastructure to run it. You make that decision according to how many users you think the site will have. But sometimes, the site can see surges of users above what was initially planned. This is where the Waiting Room can help: it stands between users and the web application and automatically creates an orderly queue during traffic spikes.
