use OnceLock for global config state

src/config.rs

@@ -0,0 +1,28 @@
+use std::{env, sync::OnceLock};
+
+use dotenvy::dotenv;
+
+static CONFIG: OnceLock<Config> = OnceLock::new();
+
+pub struct Config {
+    pub zauth_url: String,
+    pub db_uri: String,
+}
+
+impl Config {
+    pub fn initialize() {
+        assert!(CONFIG.get().is_none());
+
+        Config::get();
+    }
+
+    pub fn get() -> &'static Config {
+        CONFIG.get_or_init(|| {
+            dotenv().ok();
+            Config {
+                db_uri: env::var("DATABASE_URL").expect("DATABASE_URL must be set"),
+                zauth_url: env::var("ZAUTH_URL").expect("ZAUTH_URL must be set"),
+            }
+        })
+    }
+}

src/db/lib.rs

@@ -1,9 +1,10 @@
 use diesel::prelude::*;
 use diesel::sqlite::SqliteConnection;
-use std::env;
+
+use crate::config::Config;
 
 pub fn establish_connection() -> SqliteConnection {
-    let database_url = env::var("DATABASE_URL").expect("DATABASE_URL must be set");
+    let database_url = Config::get().db_uri.clone();
     SqliteConnection::establish(&database_url)
-        .unwrap_or_else(|_| panic!("Error connecting to {}", database_url))
+        .unwrap_or_else(|_| panic!("Error connecting to {}", Config::get().db_uri))
 }

src/handlers/update/authenticate.rs

@@ -1,8 +1,6 @@
-use std::env;
-
 use reqwest::Error;
 
-use crate::errors::AuthenticationError;
+use crate::{config::Config, errors::AuthenticationError};
 
 use super::sig::{PublicKey, Sig};
 
@@ -38,11 +36,12 @@ pub(super) async fn authenticate(sig: &Sig, zone: &Vec<String>) -> Result<bool>
 }
 
 async fn get_keys(username: &String) -> std::result::Result<SSHKeys, Error> {
-    let zauth_url = env::var("ZAUTH_URL").expect("ZAUTH_URL must be set");
-    Ok(
-        reqwest::get(format!("{}/users/keys/{}", zauth_url, username))
+    Ok(reqwest::get(format!(
+        "{}/users/keys/{}",
+        Config::get().zauth_url,
+        username
+    ))
     .await?
     .json::<SSHKeys>()
-            .await?,
-    )
+    .await?)
 }

src/main.rs

@@ -1,9 +1,10 @@
 use std::{error::Error, net::SocketAddr};
 
-use dotenvy::dotenv;
+use config::Config;
 
 use crate::resolver::resolver_listener_loop;
 
+mod config;
 mod db;
 mod errors;
 mod handlers;
@@ -16,8 +17,7 @@ mod utils;
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn Error>> {
-    dotenv().ok();
-
+    Config::initialize();
     let resolver_add = SocketAddr::from(([127, 0, 0, 1], 8080));
     let _ = tokio::join!(resolver_listener_loop(resolver_add),);
     Ok(())