| 1 | //! Liveness and readiness. |
| 2 | //! |
| 3 | //! `/healthz` answers whether the process is up; `/readyz` answers whether it |
| 4 | //! can serve, which means the database is reachable and the pool can still hand |
| 5 | //! out a connection. |
| 6 | //! |
| 7 | //! The container healthcheck reads `/readyz`. It used to read `/healthz` on the |
| 8 | //! reasoning that restarting on readiness turns a transient database blip into a |
| 9 | //! restart loop — but nothing restarts on either signal here (compose restarts |
| 10 | //! on exit), so all that bought was a container reporting healthy while it |
| 11 | //! served nothing but 500s. |
| 12 | |
| 13 | use axum::extract::State; |
| 14 | use axum::http::StatusCode; |
| 15 | use axum::response::IntoResponse; |
| 16 | |
| 17 | use crate::state::AppState; |
| 18 | |
| 19 | pub async fn healthz() -> impl IntoResponse { |
| 20 | (StatusCode::OK, "ok\n") |
| 21 | } |
| 22 | |
| 23 | pub async fn readyz(State(state): State<AppState>) -> impl IntoResponse { |
| 24 | // Reported either way: a pool that is at its ceiling with nothing idle is |
| 25 | // the signature of connections stuck in the pool rather than of a database |
| 26 | // that has gone away, and the two need different responses from whoever is |
| 27 | // reading this. |
| 28 | let open = state.db.size(); |
| 29 | let idle = state.db.num_idle(); |
| 30 | |
| 31 | match df_db::ping(&state.db).await { |
| 32 | Ok(()) => ( |
| 33 | StatusCode::OK, |
| 34 | format!("ready\npool: {idle} idle / {open} open\n"), |
| 35 | ), |
| 36 | Err(e) => { |
| 37 | tracing::error!( |
| 38 | pool_open = open, |
| 39 | pool_idle = idle, |
| 40 | "readiness check failed: {e}" |
| 41 | ); |
| 42 | ( |
| 43 | StatusCode::SERVICE_UNAVAILABLE, |
| 44 | format!("database unreachable\npool: {idle} idle / {open} open\n"), |
| 45 | ) |
| 46 | } |
| 47 | } |
| 48 | } |
48 lines · Rust