gitdataai/apps/email/src/main.rs

use clap::Parser;
use config::AppConfig;
use metrics::{describe_counter, Unit};
use metrics_exporter_prometheus::PrometheusHandle;
use observability::{init_tracing_subscriber, install_recorder};
use sea_orm::ConnectionTrait;
use service::AppService;
use std::sync::Arc;

#[derive(Parser, Debug)]
#[command(name = "email-worker")]
#[command(version)]
struct Args {
    #[arg(long, default_value = "info")]
    log_level: String,
}

async fn http_handler(
    db: Arc<db::database::AppDatabase>,
    cache: Arc<db::cache::AppCache>,
    metrics: Arc<PrometheusHandle>,
    req: hyper::Request<hyper::Body>,
) -> Result<hyper::Response<hyper::Body>, std::convert::Infallible> {
    match req.uri().path() {
        "/health" => {
            let writer_ok = db
                .writer()
                .execute_unprepared("SELECT 1")
                .await
                .is_ok();
            let reader_ok = db
                .reader()
                .execute_unprepared("SELECT 1")
                .await
                .is_ok();
            let db_ok = writer_ok && reader_ok;
            let cache_ok = cache.conn().await.is_ok();

            let body = serde_json::json!({
                "status": if db_ok && cache_ok { "ok" } else { "unhealthy" },
                "db": if db_ok { "ok" } else { "error" },
                "cache": if cache_ok { "ok" } else { "error" },
            });

            let status = if db_ok && cache_ok { 200 } else { 503 };
            Ok(hyper::Response::builder()
                .status(status)
                .header("content-type", "application/json")
                .body(hyper::Body::from(serde_json::to_string(&body).unwrap()))
                .unwrap())
        }
        "/metrics" => {
            let body = metrics.render();
            Ok(hyper::Response::builder()
                .status(200)
                .header("content-type", "text/plain; version=0.0.4; charset=utf-8")
                .body(hyper::Body::from(body))
                .unwrap())
        }
        _ => Ok(hyper::Response::builder()
            .status(404)
            .body(hyper::Body::from("not found"))
            .unwrap()),
    }
}

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let args = Args::parse();
    let cfg = AppConfig::load();
    init_tracing_subscriber(&args.log_level, false);

    // Pre-register all email/queue metrics so they appear in /metrics even before first event.
    describe_counter!("email_queued_total", Unit::Count, "Emails written to Redis stream");
    describe_counter!("email_consumed_total", Unit::Count, "Emails consumed from queue");
    describe_counter!("email_batch_size", Unit::Count, "Email consumer batch sizes accumulated");
    describe_counter!("email_validation_skipped_total", Unit::Count, "Emails skipped due to invalid recipient");
    describe_counter!("email_build_errors_total", Unit::Count, "Email message build failures");
    describe_counter!("email_send_attempts_total", Unit::Count, "SMTP send attempts (including retries)");
    describe_counter!("email_sent_total", Unit::Count, "Emails sent successfully");
    describe_counter!("email_send_failures_total", Unit::Count, "Emails that failed after all retries");

    let metrics_handle = Arc::new(install_recorder());

    tracing::info!("Starting email worker");
    let service = AppService::new(cfg).await?;

    let db = Arc::new(service.db.clone());
    let cache = Arc::new(service.cache.clone());

    let (shutdown_tx, shutdown_rx) = tokio::sync::broadcast::channel::<()>(1);
    tokio::spawn(async move {
        tokio::signal::ctrl_c().await.ok();
        tracing::info!("shutting down email worker");
        let _ = shutdown_tx.send(());
    });

    // Start health/metrics server on a dedicated port
    let health_db = db.clone();
    let health_cache = cache.clone();
    let health_metrics = metrics_handle.clone();
    let health_addr: std::net::SocketAddr = ([0, 0, 0, 0], 8084).into();
    let health_service = hyper::service::make_service_fn(move |_| {
        let db = health_db.clone();
        let cache = health_cache.clone();
        let metrics = health_metrics.clone();
        let service = hyper::service::service_fn(move |req| {
            http_handler(db.clone(), cache.clone(), metrics.clone(), req)
        });
        async move { Ok::<_, std::convert::Infallible>(service) }
    });

    let health_server = hyper::Server::bind(&health_addr).serve(health_service);
    tracing::info!(port = 8084, "health/metrics server started");
    tokio::spawn(async move {
        if let Err(e) = health_server.await {
            tracing::error!("health check server error: {}", e);
        }
    });

    service.start_email_workers(shutdown_rx).await?;
    tracing::info!("email worker stopped");
    Ok(())
}