Axum and SQLx interoperability guide

Rullst builds on Axum, Tokio, Tower and SQLx and preserves direct access to their APIs. This reduces coupling for HTTP and database code; it does not make every optional framework subsystem free to remove.

Mount an existing Axum router

rullst::Router supports conversion to and from axum::Router:

#![allow(unused)]
fn main() {
use axum::{Router as AxumRouter, routing::get};
use rullst::Router;

async fn existing_handler() -> &'static str {
    "existing Axum route"
}

let existing = AxumRouter::new().route("/existing", get(existing_handler));
let rullst_router: Router = existing.into();
let axum_router: AxumRouter = rullst_router.into();
let _ = axum_router;
}

The standard Axum extractor and response types remain available, including through Rullst’s documented re-exports.

Keep raw SQLx where it is useful

Application-owned SQL can live beside generated ORM queries. Bind every dynamic value and review structural SQL separately:

#![allow(unused)]
fn main() {
use sqlx::PgPool;

async fn active_names(pool: &PgPool) -> Result<Vec<String>, sqlx::Error> {
    sqlx::query_scalar("SELECT name FROM users WHERE active = $1")
        .bind(true)
        .fetch_all(pool)
        .await
}
}

Generate an escape-hatch snapshot

cargo rullst eject
cargo check

The command writes an inspectable Axum/Tokio entry-point snapshot. Review it; ORM models, migrations, authentication policy, Studio/Nexus integration and other selected subsystems can still require deliberate migration work. Use --force only when replacing src/main.rs is intended and the worktree is backed up.

Practical migration sequence

1. Keep domain types and handlers independent of framework globals.
2. Convert router boundaries incrementally.
3. Replace generated ORM calls with raw SQLx only where that trade-off helps.
4. Inventory authentication, middleware order, jobs, cache and admin surfaces.
5. Run application-specific integration and authorization tests before removing dependencies.

Interoperability is a maintained design goal. “Zero lock-in” or zero migration cost is not a framework guarantee.