Use Rocket's Figment for configuration

Instead of reading our own TOML file for configuration, we can hook into
Rocket's [built-in configuration system][0].  Although it doesn't matter
much right now, it may if we end up using Rocket's SQL [database
integration][1], because it uses the same mechanism.  Without making
this change, we would end up with two configuration files in that case.

[0]: https://rocket.rs/guide/v0.5/configuration/#extracting-values
[1]: https://rocket.rs/guide/v0.5/state/#databases

.gitignore

@@ -1,3 +1,3 @@
-/config.toml
+/Rocket.toml
 /firefly.token
 /target

Cargo.lock

@@ -1645,7 +1645,6 @@ dependencies = [
  "rocket_dyn_templates",
  "serde",
  "thiserror",
- "toml",
  "tracing",
  "tracing-subscriber",
 ]

Cargo.toml

@@ -16,6 +16,5 @@ rocket = { version = "0.5.1", default-features = false, features = ["json"] }
 rocket_dyn_templates = { version = "0.2.0", features = ["tera"] }
 serde = { version = "1.0.218", default-features = false, features = ["derive"] }
 thiserror = "2.0.12"
-toml = "0.8.20"
 tracing = "0.1.41"
 tracing-subscriber = { version = "0.3.19", features = ["env-filter"] }

Containerfile

@@ -46,4 +46,4 @@ WORKDIR /usr/local/share/receipts
 
 ENTRYPOINT ["/usr/local/bin/receipts"]
 
-CMD ["/etc/receipts/config.toml"]
+ENV ROCKET_CONFIG=/etc/receipts/config.toml

src/config.rs

@@ -1,15 +1,7 @@
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 
 use serde::Deserialize;
 
-#[derive(Debug, thiserror::Error)]
-pub enum ConfigError {
-    #[error("Unable to load file: {0}")]
-    Io(#[from] std::io::Error),
-    #[error("Error parsing file: {0}")]
-    Toml(#[from] toml::de::Error),
-}
-
 #[derive(Debug, Deserialize)]
 pub struct FireflyConfig {
     pub url: String,
@@ -21,10 +13,3 @@ pub struct FireflyConfig {
 pub struct Config {
     pub firefly: FireflyConfig,
 }
-
-impl Config {
-    pub fn from_file(path: impl AsRef<Path>) -> Result<Self, ConfigError> {
-        let data = std::fs::read_to_string(path)?;
-        Ok(toml::from_str(&data)?)
-    }
-}

src/main.rs

@@ -1,8 +1,6 @@
 mod config;
 mod firefly;
 
-use std::path::{Path, PathBuf};
-
 use rocket::form::Form;
 use rocket::fs::{FileServer, TempFile};
 use rocket::http::Status;
@@ -13,7 +11,7 @@ use rocket_dyn_templates::{context, Template};
 use serde::Serialize;
 use tracing::{debug, error};
 
-use config::{Config, ConfigError};
+use config::Config;
 use firefly::{
     Firefly, TransactionRead, TransactionSplitUpdate, TransactionUpdate,
 };
@@ -27,14 +25,13 @@ struct Context {
 #[derive(Debug, thiserror::Error)]
 enum InitError {
     #[error("Invalid config: {0}")]
-    Config(#[from] ConfigError),
+    Config(std::io::Error),
 }
 
 impl Context {
-    pub fn init(config: impl AsRef<Path>) -> Result<Self, InitError> {
-        let config = Config::from_file(config)?;
+    pub fn init(config: Config) -> Result<Self, InitError> {
         let token = std::fs::read_to_string(&config.firefly.token)
-            .map_err(ConfigError::from)?;
+            .map_err(InitError::Config)?;
         let firefly = Firefly::new(&config.firefly.url, &token);
         Ok(Self { config, firefly })
     }
@@ -233,13 +230,12 @@ async fn rocket() -> _ {
         .with_writer(std::io::stderr)
         .init();
 
-    let cfg_path = match std::env::args_os().nth(1) {
-        Some(f) => PathBuf::from(f),
-        None => PathBuf::from("config.toml"),
-    };
-    debug!("Using configuration file {}", cfg_path.display());
+    let rocket = rocket::build();
+    let figment = rocket.figment();
 
-    let ctx = match Context::init(cfg_path) {
+    let config: Config = figment.extract().unwrap();
+
+    let ctx = match Context::init(config) {
         Ok(c) => c,
         Err(e) => {
             error!("Failed to initialize application context: {}", e);
@@ -248,7 +244,7 @@ async fn rocket() -> _ {
     };
     debug!("Using Firefly III URL {}", &ctx.firefly.url());
 
-    rocket::build()
+    rocket
         .manage(ctx)
         .mount(
             "/",