Zero in a Durable Object

This runs Zero in a Cloudflare Durable Object. It's a simple example, but it proves that it's possible to run Zero in a Durable Object.

Why run Zero in DO?

This sample was written for a Zero user who was running collaboration sessions in DOs. Sometimes they needed to force shut down these DOs. It would be unreliable to send every DO a message telling it to shut down. But if they wrote the state into a DB and instead synced that state, it would be perfectly reliable. The DO would just monitor what state it is supposed to be in and shut itself down when necessary.

More generally any time a DO needs some subset of PG data, it could be useful to have a live-updated, consistent view of it rather than having to query.

Running

We need 4 different terminals to run this example!

1. Run Posgres

Start a Postgres database using docker

npm run dev:db-up

2. Run Zero Cache

Start a Zero cache server

npm run dev:zero-cache

3. Run Web App

This is to add and remove messages to Postgres. This web app uses Zero too.

npm run dev:ui

Open a browser at http://localhost:5173 to add and remove messages.

4. Run Durable Object

npx wrangler dev

Open a browser at http://localhost:8787. This will create the Durable Object which creates the Zero client in the DO.

Then make changes in the web UI and observe the console output from wrangler.