Don't panic!

src/config.rs

@@ -1,3 +1,4 @@
+use anyhow::{Context, Result};
 use serde::Deserialize;
 use std::env;
 use std::fs::File;
@@ -26,18 +27,17 @@ pub struct Config {
 }
 
 impl Config {
-    pub fn new() -> Self {
+    pub fn new() -> Result<Self> {
         let config_file_var = "CF_CONFIG_FILE";
         let config_path = env::var(config_file_var)
-            .unwrap_or_else(|_| panic!("Environment variable {config_file_var} missing!"));
+            .with_context(|| format!("Environment variable {config_file_var} missing!"))?;
 
-        let config_file = File::open(&config_path).unwrap_or_else(|e| {
+        let config_file = File::open(&config_path)
-            panic!("Can not open the config file at the path {config_path}: {e}")
+            .with_context(|| format!("Can not open the config file at the path {config_path}"))?;
-        });
         let config_reader = BufReader::new(config_file);
-        let config: Self =
+        let config: Self = serde_json::from_reader(config_reader)
-            serde_json::from_reader(config_reader).expect("Can not parse the config file as JSON!");
+            .context("Can not parse the config file as JSON!")?;
 
-        config
+        Ok(config)
     }
 }

src/main.rs

@@ -5,19 +5,31 @@ mod forms;
 mod mailer;
 mod routes;
 
+use anyhow::Result;
+use rocket::{Build, Rocket};
 use rocket_dyn_templates::Template;
+use std::process;
 
-#[rocket::launch]
+fn init() -> Result<Rocket<Build>> {
-fn rocket() -> _ {
+    let mut config = config::Config::new()?;
-    let mut config = config::Config::new();
 
-    rocket::build()
+    let rocket = rocket::build()
         .mount(
             &config.path_prefix,
             rocket::routes![routes::index, routes::submit, routes::success],
         )
         .manage(captcha_solutions::SharedCaptchaSolutions::new())
-        .manage(mailer::Mailer::new(&mut config).expect("Failed to create mailer!"))
+        .manage(mailer::Mailer::new(&mut config)?)
         .manage(config)
-        .attach(Template::fairing())
+        .attach(Template::fairing());
+
+    Ok(rocket)
+}
+
+#[rocket::launch]
+fn rocket() -> _ {
+    init().unwrap_or_else(|e| {
+        eprintln!("{e}");
+        process::exit(1);
+    })
 }