From 6b2ff5a87f2144de9b91c4e2679854626994d5b4 Mon Sep 17 00:00:00 2001
From: sqwishy <somebody@froghat.ca>
Date: Tue, 9 Aug 2022 00:47:48 -0700
Subject: [PATCH] DATABASE_CONNECTIONS sets Pool max_connections (#376)

If unspecified, defaults to the current value of 100
---
 backend/src/db.rs  |  4 ++--
 backend/src/lib.rs | 10 +++++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/backend/src/db.rs b/backend/src/db.rs
index 00228a9e96..c486c7b7c6 100644
--- a/backend/src/db.rs
+++ b/backend/src/db.rs
@@ -12,9 +12,9 @@ use std::time::Duration;
 
 pub type DB = Pool<Postgres>;
 
-pub async fn connect(database_url: &str) -> Result<DB, Error> {
+pub async fn connect(database_url: &str, max_connections: u32) -> Result<DB, Error> {
     PgPoolOptions::new()
-        .max_connections(100)
+        .max_connections(max_connections)
         .max_lifetime(Duration::from_secs(30 * 60)) // 30 mins
         .connect(database_url)
         .await
diff --git a/backend/src/lib.rs b/backend/src/lib.rs
index c7715fceda..9eeb1f8664 100644
--- a/backend/src/lib.rs
+++ b/backend/src/lib.rs
@@ -6,6 +6,7 @@
  * LICENSE-AGPL for a copy of the license.
  */
 
+use anyhow::Context;
 use argon2::Argon2;
 use axum::{handler::Handler, middleware::from_extractor, routing::get, Extension, Router};
 use db::DB;
@@ -62,6 +63,7 @@ const GIT_VERSION: &str = git_version!(args = ["--tag", "--always"], fallback =
 pub const DEFAULT_NUM_WORKERS: usize = 3;
 pub const DEFAULT_TIMEOUT: i32 = 300;
 pub const DEFAULT_SLEEP_QUEUE: u64 = 50;
+pub const DEFAULT_MAX_CONNECTIONS: u32 = 100;
 
 pub async fn migrate_db(db: &DB) -> anyhow::Result<()> {
     let app_password = std::env::var("APP_USER_PASSWORD").unwrap_or_else(|_| "changeme".to_owned());
@@ -74,7 +76,13 @@ pub async fn migrate_db(db: &DB) -> anyhow::Result<()> {
 pub async fn connect_db() -> anyhow::Result<DB> {
     let database_url = std::env::var("DATABASE_URL")
         .map_err(|_| Error::BadConfig("DATABASE_URL env var is missing".to_string()))?;
-    Ok(db::connect(&database_url).await?)
+
+    let max_connections = match std::env::var("DATABASE_CONNECTIONS") {
+        Ok(n) => n.parse::<u32>().context("invalid DATABASE_CONNECTIONS")?,
+        Err(_) => DEFAULT_MAX_CONNECTIONS,
+    };
+
+    Ok(db::connect(&database_url, max_connections).await?)
 }
 
 pub async fn initialize_tracing() -> anyhow::Result<()> {