With containers, virtualized processes run natively in the host kernel, like any other. Except that their I/Os are carefully kept segregated from others in the host system.

Thought: containers are often too heavy for the job.

The root cause behind the heavy weight of containers is that they have been built for too many usecases.

WASI is a standard API to give WASM code the ability to do system-level I/O.

Solution?

To try to address this, we wanted to move all these heavy dependencies to a common runtime across services. So your tokio, hyper, sqlx and co (in the case of Rust), now all belong to a long-lived containerized process running persistently in the cloud. Whereas all your service logic, database and endpoint code build into lightweight WASM modules that are dynamically loaded in-place by this global persistent process.