[don-code]

I recently had an opportunity to build an application on top of Lambda@Edge (AWS's equivalent of Cloudflare workers). The prevailing wisdom there was to make use of regional services, like S3 and DynamoDB, from the edge. That, of course, makes my edge application depend on calls to a larger, further away point of presence.

While it's possible to distribute state to many AWS regions and select the closest one, I ended up going a different route: packaging state alongside the application. Most of the application's state was read-only, so I ended up packaging the application state up as JSON alongside the deployment bundle. At startup, it'd then statically read the JSON into memory - this performance penalty only happens at startup, and as long as the Lambda functions are being called often (in our case they are), requests are as fast as a memory read.

When the state does need to get updated, I just redeploy the application with the new state.

That strategy obviously won't work if you need "fast" turnaround on your state being in sync at all points of presence, or if users can update that state as part of your application's workflow.

[chucky_z]

I think this is a really clear winner for something like Litestream, where you can have state far away but sync it locally with periodic syncs if you can live with 'small wait on startup' and 'periodic state updates'.

[powersurge360]

Isn't this effectively the same as using a static site generator? Could you potentially freeze or pre-bake your generated files and then just serve that?

[geewee]

We do something similar in Climatiq on Fastly's Compute@Edge. When building the application we load in a big chunk of read-only data in-memory, and serialize that memory to a file. When we spin up our instance, all we have to do is load that file into memory and then we have tons of read-only data in just a few ms.

[KajMagnus]

> I just redeploy the application with the new state.

How long does that take? From clicking Deploy until the app got updated? ... and until it's restarted and the new state is available?

Could this depend a bit on how far away a data center is? Maybe 200ms longer for some?