main.rs

use diesel::{ConnectionError, ConnectionResult};
use diesel_async::async_connection_wrapper::AsyncConnectionWrapper;
use diesel_async::AsyncPgConnection;
use diesel_migrations::{embed_migrations, EmbeddedMigrations, MigrationHarness};
use futures_util::future::BoxFuture;
use futures_util::FutureExt;
use rustls::ClientConfig;
use rustls_platform_verifier::ConfigVerifierExt;

pub const MIGRATIONS: EmbeddedMigrations = embed_migrations!();

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Should be in the form of postgres://user:password@localhost/database?sslmode=require
    let db_url = std::env::var("DATABASE_URL").expect("Env var `DATABASE_URL` not set");

    let async_connection = establish_connection(db_url.as_str()).await?;

    let mut async_wrapper: AsyncConnectionWrapper<AsyncPgConnection> =
        AsyncConnectionWrapper::from(async_connection);

    tokio::task::spawn_blocking(move || {
        async_wrapper.run_pending_migrations(MIGRATIONS).unwrap();
    })
    .await?;

    Ok(())
}

fn establish_connection(config: &str) -> BoxFuture<ConnectionResult<AsyncPgConnection>> {
    let fut = async {
        // We first set up the way we want rustls to work.
        let rustls_config = ClientConfig::with_platform_verifier();
        let tls = tokio_postgres_rustls::MakeRustlsConnect::new(rustls_config);
        let (client, conn) = tokio_postgres::connect(config, tls)
            .await
            .map_err(|e| ConnectionError::BadConnection(e.to_string()))?;
        AsyncPgConnection::try_from_client_and_connection(client, conn).await
    };
    fut.boxed()
}