rustauth-diesel

Diesel database adapters for RustAuth.

This crate provides async-only Diesel integrations for Postgres and MySQL. It builds on diesel-async deadpool pooling and RustAuth's shared SQL runner in rustauth-core. The public crate name is rustauth-diesel; configure CLI migrations with database.adapter = "diesel".

SQLite is not supported. Use rustauth-sqlx for SQLite (local dev, tests, or small deployments). Sync Diesel is not exposed either.

When to use Diesel vs SQLx

Your stack	RustAuth adapter
App uses Diesel for Postgres or MySQL in production	`rustauth-diesel` (`postgres` / `mysql`)
Local dev, tests, or production on SQLite	`rustauth-sqlx` with `sqlite`
App uses SQLx for Postgres, MySQL, or SQLite	`rustauth-sqlx` — no need to add Diesel
"Diesel everywhere" shop wanting SQLite locally	Use `rustauth-sqlx` for the auth storage slice, or run Postgres in Docker for parity with prod

RustAuth intentionally ships one SQLite path: native async SQLx. Diesel SQLite in diesel-async routes every query through SyncConnectionWrapper (spawn_blocking over a sync connection), which is a poor fit for concurrent auth CRUD, transactions, and SQL-backed rate limits. There is no incremental user value over the existing SQLx adapter (~1900 lines of SQLite tests, CLI migrations, transactional apply).

Install

Postgres:

[dependencies]
rustauth-diesel = { version = "0.2", features = ["postgres"] }
tokio = { version = "1", features = ["macros", "rt-multi-thread"] }

MySQL:

[dependencies]
rustauth-diesel = { version = "0.2", features = ["mysql"] }
tokio = { version = "1", features = ["macros", "rt-multi-thread"] }

Both backends:

[dependencies]
rustauth-diesel = { version = "0.2", features = ["postgres", "mysql"] }
tokio = { version = "1", features = ["macros", "rt-multi-thread"] }

Via the rustauth facade, enable diesel-postgres or diesel-mysql and import types from rustauth::diesel.

Features

Feature	Backend	Types
`postgres`	PostgreSQL	`DieselPostgresAdapter`, `DieselPostgresStores`, `DieselPostgresRateLimitStore`
`mysql`	MySQL	`DieselMysqlAdapter`, `DieselMysqlStores`, `DieselMysqlRateLimitStore`

default = [] — enable the backend(s) you need.

Postgres adapter

Adapter id: diesel-postgres.

use rustauth_diesel::DieselPostgresAdapter;

let adapter = DieselPostgresAdapter::connect(
    "postgres://user:password@localhost:5432/rustauth",
)
.await?;

Bundled adapter + SQL-backed rate-limit store:

use rustauth_diesel::DieselPostgresStores;

let stores = DieselPostgresStores::connect(
    "postgres://user:password@localhost:5432/rustauth",
)
.await?;
let options = stores.apply_to_options(rustauth_core::options::RustAuthOptions::default());

MySQL adapter

Adapter id: diesel-mysql.

use rustauth_diesel::DieselMysqlAdapter;

let adapter = DieselMysqlAdapter::connect(
    "mysql://user:password@localhost:3306/rustauth",
)
.await?;

Bundled adapter + SQL-backed rate-limit store:

use rustauth_diesel::DieselMysqlStores;

let stores = DieselMysqlStores::connect(
    "mysql://user:password@localhost:3306/rustauth",
)
.await?;
let options = stores.apply_to_options(rustauth_core::options::RustAuthOptions::default());

CLI migrations

Configure rustauth.toml with database.adapter = "diesel" and the matching provider (postgres or mysql):

[database]
adapter = "diesel"
provider = "postgres"
url_env = "DATABASE_URL"

cargo install rustauth-cli --features diesel
rustauth db status
rustauth db migrate --yes

Diesel migration support uses RustAuth's SQL migration planner through this adapter. It does not use Diesel's migration CLI as a second source of schema truth.

Do not configure database.adapter = "diesel-async". The adapter string is diesel; diesel-async is an internal driver dependency only.

Behavior notes

Uses diesel-async internally with deadpool connection pooling (Postgres/MySQL only).
SQLite is not supported — see When to use Diesel vs SQLx.
Sync Diesel is not exposed; RustAuth's DbAdapter contract is async-only.
MySQL array columns are JSON-backed where the shared SQL planner emits array types Postgres handles natively.

Row decoding

Dynamic query results use backend-specific QueryableByName row types (DieselPostgresRow, DieselMysqlRow) that capture column values at build time, then decode through the shared SqlRowReader boundary.

See NOTES.md for the plan 013 feasibility decision record.

Tests

./scripts/ensure-test-services.sh postgres
cargo nextest run -p rustauth-diesel --features postgres --test diesel_feasibility
cargo nextest run -p rustauth-diesel --features postgres --test postgres_adapter

./scripts/ensure-test-services.sh mysql
cargo nextest run -p rustauth-diesel --features mysql --test diesel_feasibility
cargo nextest run -p rustauth-diesel --features mysql --test mysql_adapter

For route-level parity, test counts, differences, and gaps, see UPSTREAM.md.

rustauth-diesel 0.3.1