In a blink of an eye: Apply CDN settings instantly

Today marks a big milestone for user experience at pushr and the culmination of a 9 months long behind-the-scenes effort, which has resulted in a rather quiet 2024 in terms of updates and new features from us. We've rewritten nearly every part of our edge engine, from DNS to CDN to Storage and global config synchronization. We've improved the speed, reliability and compatibility of all services. And we've just released instant global CDN configuration updates. Let's start with that.

From click to global: Apply CDN settings in less than 1 second 🌏

Throughout the years the system that we use to apply changes that you make in the settings of your CDN zones to our entire edge network has seen multiple complete overhauls. In its first iteration, it would take between 1 and 3 minutes of waiting time for changes to be applied. This first generation could sometimes cause an edge server to miss an update, so we've scrapped it. In the second iteration, the average time would be 1 minute and a new process that would periodically check for updates consistency was introduced. This fixed the missed updates issue, but was still less than ideal. We've releaized that for most people, if they click a button and we show them a green message with a confirmation, they would consider the change to be applied. In reality, the confirmation message would start the update process instead and it would not be clear how long it might take for the change to actually apply globally. 

The third generation of this system has just been released and we are excited to see it in action. This new generation has been built from the ground up and is capable of applying changes in less than 140ms, with an average of 250ms globally. Which also happens to be the average time that it takes for a regular person to blink 👀

Behind the curtains, the system introduces a new 2-layer approach for instant config propagation, including a set of hot-reload servers that are separate from our edge servers. These receive and apply the updates in 120 milliseconds on average and will hold only a limited amount of recently changed CDN zones' configurations. At the same time, a small routing file that instructs our edge network is streamed to all edge servers to immediately start routing traffic to the hot-reloads. The process then sends the full update to the edge servers and allows them to gracefully reload the configuration, which might take a few seconds. Once the reload is complete, the edge servers will stop routing the traffic to the hot-reload proxies and will continue to serve it themselves with the new settings applied. 

Global DNS updates in less than 1 second ⚡

At pushr we run a global anycast network of DNS servers that are responsible for the CDN hostnames that you serve your CDN zone traffic from. This network of servers runs our name server software that maps domains to IP addresses and responds to queries for your CDN zone whenever someone wants to access your content. This process should be fast because it is part of a metric called TTFB (Time To First Byte) and TTFB is important for user experience and SEO. Our anycast network serves the query from the closest server, so the visitors could then know to connect to the closest edge server to them. The edge server will then serve the content requested. But none of this would work if the there is no record of your CDN zone on the anycast network yet. Even worse, browsers tend to cache DNS errors for a random period of time and this could easily make a visitor think that your website or content are not working.

We've rewritten pushr's DNS synchronization system and are now pushing updates with changes to existing hostnames as well as newly added custom hostnames in less than 0.8 seconds on average.

Faster SSL certificates 🔓

When you enable HTTPS for a custom hostname that you have added to your CDN zone, pushr will contact it's certificate server to request an SSL certificate to be issued. The certificate server will then create a validation challenge and will contact Letsencrypt - the certificate authority that issues the certificate - to obtain the certificate. Previously, this process would take up to a minute. We've rewritten the entire process and it now takes less than 20 seconds for HTTPS connections to start working properly on your new hostnames once you've enabled them in your dashboard. 

Better origin server handling ✨

We've completely rewritten the CDN zone configuration templates to improve compatibility with various origin server setups, including less typical ones that could previously cause request errors. This change also enables the path for pushr forward and provides the proper ground on which we are building the services shared previously on our roadmap. 

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