From 71814376250ccc1d5f1ec1518138d5edfa24dd7d Mon Sep 17 00:00:00 2001
From: Anders Olsson <anders.e.olsson@gmail.com>
Date: Thu, 4 Jun 2026 21:46:41 +0200
Subject: [PATCH] feat(server): configurable DB pool size via
 --db-max-connections/DB_MAX_CONNECTIONS (#2)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 crates/db/src/lib.rs         | 7 ++++---
 crates/server/src/config.rs  | 8 ++++++++
 crates/server/src/lib.rs     | 5 +++--
 crates/server/tests/serve.rs | 2 +-
 4 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/crates/db/src/lib.rs b/crates/db/src/lib.rs
index 17267b8..0f1c2fa 100644
--- a/crates/db/src/lib.rs
+++ b/crates/db/src/lib.rs
@@ -17,10 +17,11 @@ pub struct Db {
 }
 
 impl Db {
-    /// Connect to the database at `database_url`, opening a connection pool.
-    pub async fn connect(database_url: &str) -> Result<Self, sqlx::Error> {
+    /// Connect to the database at `database_url`, opening a connection pool with at most
+    /// `max_connections` connections.
+    pub async fn connect(database_url: &str, max_connections: u32) -> Result<Self, sqlx::Error> {
         let pool = PgPoolOptions::new()
-            .max_connections(5)
+            .max_connections(max_connections)
             .connect(database_url)
             .await?;
 
diff --git a/crates/server/src/config.rs b/crates/server/src/config.rs
index 0182938..08e809e 100644
--- a/crates/server/src/config.rs
+++ b/crates/server/src/config.rs
@@ -42,4 +42,12 @@ pub struct Config {
     /// Meilisearch index name for catalogue objects.
     #[arg(long = "meili-index", env = "MEILI_INDEX", default_value = "objects")]
     pub meili_index: String,
+
+    /// Maximum size of the PostgreSQL connection pool.
+    #[arg(
+        long = "db-max-connections",
+        env = "DB_MAX_CONNECTIONS",
+        default_value_t = 5
+    )]
+    pub db_max_connections: u32,
 }
diff --git a/crates/server/src/lib.rs b/crates/server/src/lib.rs
index ff2d3bc..53951b2 100644
--- a/crates/server/src/lib.rs
+++ b/crates/server/src/lib.rs
@@ -15,7 +15,7 @@ use tokio::net::TcpListener;
 
 /// Connect dependencies from `config` and serve until shutdown.
 pub async fn run(config: Config) -> anyhow::Result<()> {
-    let db = Db::connect(&config.database_url)
+    let db = Db::connect(&config.database_url, config.db_max_connections)
         .await
         .context("connecting to the database")?;
 
@@ -136,7 +136,8 @@ pub async fn create_user(database_url: &str, email: &str, role: Role) -> anyhow:
         auth::hash_password(&password).map_err(|err| anyhow::anyhow!("hashing password: {err}"))?
     };
 
-    let db = Db::connect(database_url)
+    // CLI one-shot: a tiny pool is plenty.
+    let db = Db::connect(database_url, 2)
         .await
         .context("connecting to the database")?;
 
diff --git a/crates/server/tests/serve.rs b/crates/server/tests/serve.rs
index b3dd99d..edf402a 100644
--- a/crates/server/tests/serve.rs
+++ b/crates/server/tests/serve.rs
@@ -9,7 +9,7 @@ use tokio::net::TcpListener;
 async fn serves_health_live_over_tcp() {
     let database_url =
         std::env::var("DATABASE_URL").expect("DATABASE_URL must be set for this test");
-    let db = Db::connect(&database_url)
+    let db = Db::connect(&database_url, 2)
         .await
         .expect("connect to database");
     let state = AppState {