Crate rocket_db_pools

Asynchronous database driver connection pooling integration for Rocket.

Quickstart

1. Add rocket_db_pools as a dependency with one or more database driver features enabled:

   [dependencies.rocket_db_pools]
   version = "0.1.0"
   features = ["sqlx_sqlite"]

2. Choose a name for your database, here sqlite_logs. Configure at least a URL for the database:

   [default.databases.sqlite_logs]
   url = "/path/to/database.sqlite"

3. Derive Database for a unit type (Logs here) which wraps the selected driver’s Pool type (see the driver table) and is decorated with #[database("name")]. Attach Type::init() to your application’s Rocket to initialize the database pool:

   use rocket_db_pools::{sqlx, Database};
   
   #[derive(Database)]
   #[database("sqlite_logs")]
   struct Logs(sqlx::SqlitePool);
   
   #[launch]
   fn rocket() -> _ {
       rocket::build().attach(Logs::init())
   }

4. Use Connection<Type> as a request guard to retrieve an active database connection, which dereferences to the native type in the Connection deref column.

   use rocket_db_pools::Connection;
   use rocket_db_pools::sqlx::Row;
   
   #[get("/<id>")]
   async fn read(mut db: Connection<Logs>, id: i64) -> Option<Log> {
       sqlx::query("SELECT content FROM logs WHERE id = ?").bind(id)
           .fetch_one(&mut **db).await
           .and_then(|r| Ok(Log(r.try_get(0)?)))
           .ok()
   }

   Alternatively, use a reference to the database type as a request guard to retrieve the entire pool, but note that unlike retrieving a Connection, doing so does not guarantee that a connection is available:

   use rocket_db_pools::sqlx::Row;
   
   #[get("/<id>")]
   async fn read(db: &Logs, id: i64) -> Option<Log> {
       sqlx::query("SELECT content FROM logs WHERE id = ?").bind(id)
           .fetch_one(&db.0).await
           .and_then(|r| Ok(Log(r.try_get(0)?)))
           .ok()
   }

Supported Drivers

At present, this crate supports four drivers: deadpool, sqlx, mongodb, and diesel. Each driver may support multiple databases. Drivers have a varying degree of support for graceful shutdown, affected by the Type::init() fairing on Rocket shutdown.

deadpool (v0.12)

Database	Feature	Pool Type	Connection Deref
Postgres	deadpool_postgres (v0.14)	deadpool_postgres::Pool	deadpool_postgres::ClientWrapper
Redis	deadpool_redis (v0.16)	deadpool_redis::Pool	deadpool_redis::Connection

On shutdown, new connections are denied. Shutdown does not wait for connections to be returned.

sqlx (v0.7)

Database	Feature	Pool Type	Connection Deref
Postgres	sqlx_postgres	sqlx::PgPool	sqlx::pool::PoolConnection<Postgres>
MySQL	sqlx_mysql	sqlx::MySqlPool	sqlx::pool::PoolConnection<MySql>
SQLite	sqlx_sqlite	sqlx::SqlitePool	sqlx::pool::PoolConnection<Sqlite>

On shutdown, new connections are denied. Shutdown waits for connections to be returned.

mongodb (v3)

Database	Feature	Pool Type and Connection Deref
MongoDB	mongodb	mongodb::Client

Graceful shutdown is not supported.

diesel (v2)

Database	Feature	Pool Type	Connection Deref
Postgres	diesel_postgres	diesel::PgPool	diesel::AsyncPgConnection
MySQL	diesel_mysql	diesel::MysqlPool	diesel::AsyncMysqlConnection

See diesel for usage details.

On shutdown, new connections are denied. Shutdown does not wait for connections to be returned.

Enabling Additional Driver Features

Only the minimal features for each driver crate are enabled by rocket_db_pools. To use additional driver functionality exposed via its crate’s features, you’ll need to depend on the crate directly with those features enabled in Cargo.toml:

[dependencies.sqlx]
version = "0.7"
default-features = false
features = ["macros", "migrate"]

[dependencies.rocket_db_pools]
version = "0.1.0"
features = ["sqlx_sqlite"]

Configuration

Configuration for a database named db_name is deserialized from a databases.db_name configuration parameter into a Config structure via Rocket’s configuration facilities. By default, configuration can be provided in Rocket.toml:

[default.databases.db_name]
url = "db.sqlite"

# Only `url` is required. These have sane defaults and are optional.
min_connections = 64
max_connections = 1024
connect_timeout = 5
idle_timeout = 120

# This option is only supported by the `sqlx_sqlite` driver.
extensions = ["memvfs", "rot13"]

Or via environment variables:

ROCKET_DATABASES='{db_name={url="db.sqlite",idle_timeout=120}}'

See Config for details on configuration parameters.

Note: deadpool and diesel drivers do not support and thus ignore the min_connections value.

Driver Defaults

Some drivers provide configuration defaults different from the underlying database’s defaults. A best-effort attempt is made to document those differences below:

• sqlx_sqlite

  • foreign keys : enabled
  • journal mode : WAL
  • create-missing : enabled
  • synchronous : full (even when WAL)
  • busy timeout : connection_timeout

• sqlx_postgres

  • sslmode : prefer
  • statement-cache-capacity : 100
  • user : result of whoami

• sqlx_mysql

  • sslmode : PREFERRED
  • statement-cache-capacity : 100

Extending

Any database driver can implement support for this library by implementing the Pool trait.

Re-exports

• pub use rocket;
• pub use deadpool_postgres;
• pub use deadpool_redis;
• pub use mongodb;
• pub use sqlx;

Modules

• diesel
  Re-export of diesel with prelude types overridden with async variants from diesel_async.
• figment
  Re-export of the figment crate. Semi-hierarchical configuration so con-free, it’s unreal.

Structs

• Config
  Base configuration for all database drivers.
• Connection
  A request guard which retrieves a single connection to a Database.
• Initializer
  A Fairing which initializes a Database and its connection pool.

Enums

• Error
  A general error type for use by Pool implementors and returned by the Connection request guard.

Traits

• Database
  Derivable trait which ties a database Pool with a configuration name.
• Pool
  Generic Database driver connection pool trait.

Derive Macros

• Database
  Automatic derive for the Database trait.