Add config using environment variables with figment

Cargo.lock

@@ -495,6 +495,15 @@ dependencies = [
  "num-traits",
 ]
 
+[[package]]
+name = "atomic"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d818003e740b63afc82337e3160717f4f63078720a810b7b903e70a5d1d2994"
+dependencies = [
+ "bytemuck",
+]
+
 [[package]]
 name = "atomic-waker"
 version = "1.1.2"
@@ -650,6 +659,12 @@ version = "3.17.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1628fb46dfa0b37568d12e5edd512553eccf6a22a78e8bde00bb4aed84d5bdbf"
 
+[[package]]
+name = "bytemuck"
+version = "1.21.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ef657dfab802224e671f5818e9a4935f9b1957ed18e58292690cc39e7a4092a3"
+
 [[package]]
 name = "byteorder"
 version = "1.5.0"
@@ -1093,6 +1108,20 @@ version = "2.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "37909eebbb50d72f9059c3b6d82c0463f2ff062c9e95845c43a6c9c0355411be"
 
+[[package]]
+name = "figment"
+version = "0.10.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8cb01cd46b0cf372153850f4c6c272d9cbea2da513e07538405148f95bd789f3"
+dependencies = [
+ "atomic",
+ "pear",
+ "serde",
+ "toml",
+ "uncased",
+ "version_check",
+]
+
 [[package]]
 name = "flate2"
 version = "1.0.35"
@@ -1735,6 +1764,12 @@ dependencies = [
  "hashbrown 0.15.2",
 ]
 
+[[package]]
+name = "inlinable_string"
+version = "0.1.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c8fae54786f62fb2918dcfae3d568594e50eb9b5c25bf04371af6fe7516452fb"
+
 [[package]]
 name = "inout"
 version = "0.1.3"
@@ -2214,6 +2249,29 @@ dependencies = [
  "sha2",
 ]
 
+[[package]]
+name = "pear"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bdeeaa00ce488657faba8ebf44ab9361f9365a97bd39ffb8a60663f57ff4b467"
+dependencies = [
+ "inlinable_string",
+ "pear_codegen",
+ "yansi",
+]
+
+[[package]]
+name = "pear_codegen"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4bab5b985dc082b345f812b7df84e1bef27e7207b39e448439ba8bd69c93f147"
+dependencies = [
+ "proc-macro2",
+ "proc-macro2-diagnostics",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "pem-rfc7468"
 version = "0.7.0"
@@ -2371,6 +2429,19 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "proc-macro2-diagnostics"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "af066a9c399a26e020ada66a034357a868728e72cd426f3adcd35f80d88d88c8"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "version_check",
+ "yansi",
+]
+
 [[package]]
 name = "prost"
 version = "0.13.4"
@@ -2766,6 +2837,7 @@ dependencies = [
  "async-trait",
  "clap",
  "dashmap",
+ "figment",
  "opentelemetry",
  "opentelemetry-otlp",
  "opentelemetry-semantic-conventions",
@@ -3878,6 +3950,15 @@ version = "1.17.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "42ff0bf0c66b8238c6f3b578df37d0b7848e55df8577b3f74f92a69acceeb825"
 
+[[package]]
+name = "uncased"
+version = "0.9.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e1b88fcfe09e89d3866a5c11019378088af2d24c3fbd4f0543f96b479ec90697"
+dependencies = [
+ "version_check",
+]
+
 [[package]]
 name = "unicase"
 version = "2.8.1"
@@ -4405,6 +4486,12 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "yansi"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cfe53a6657fd280eaa890a3bc59152892ffa3e30101319d168b781ed6529b049"
+
 [[package]]
 name = "yoke"
 version = "0.7.5"

Cargo.toml

@@ -149,6 +149,8 @@ tracing-subscriber = { version = "0.3", features = [
   "registry",
 ] }
 
+figment = { version = "0.10", features = ["env", "toml"] }
+
 rand.workspace = true
 rpassword.workspace = true
 argon2.workspace = true

README.md

@@ -48,7 +48,7 @@ rustical gen-config
 
 You'll have to set your database path to something like `/var/lib/rustical/db.sqlite3`.
 
-Next, configure the principals by creating a file specified in `auth.path` (by default `/etc/rustical/principals.toml`) and inserting your principals:
+Next, configure the principals by creating a file specified in `auth.toml.path` (by default `/etc/rustical/principals.toml`) and inserting your principals:
 
 ```toml
 [[principals]]

src/config.rs

@@ -25,14 +25,14 @@ pub struct SqliteDataStoreConfig {
 }
 
 #[derive(Debug, Deserialize, Serialize)]
-#[serde(tag = "backend", rename_all = "snake_case")]
+#[serde(rename_all = "snake_case")]
 #[serde(deny_unknown_fields)]
 pub enum DataStoreConfig {
     Sqlite(SqliteDataStoreConfig),
 }
 
 #[derive(Debug, Deserialize, Serialize)]
-#[serde(tag = "backend", rename_all = "snake_case")]
+#[serde(rename_all = "snake_case")]
 #[serde(deny_unknown_fields)]
 pub enum AuthConfig {
     Toml(TomlUserStoreConfig),

src/main.rs

@@ -6,6 +6,8 @@ use app::make_app;
 use clap::{Parser, Subcommand};
 use commands::{cmd_gen_config, cmd_pwhash};
 use config::{DataStoreConfig, SqliteDataStoreConfig};
+use figment::providers::{Env, Format, Toml};
+use figment::Figment;
 use rustical_dav::push::push_notifier;
 use rustical_nextcloud_login::NextcloudFlows;
 use rustical_store::auth::TomlPrincipalStore;
@@ -14,7 +16,6 @@ use rustical_store_sqlite::addressbook_store::SqliteAddressbookStore;
 use rustical_store_sqlite::calendar_store::SqliteCalendarStore;
 use rustical_store_sqlite::{create_db_pool, SqliteStore};
 use setup_tracing::setup_tracing;
-use std::fs;
 use std::sync::Arc;
 use tokio::sync::mpsc::Receiver;
 
@@ -72,11 +73,11 @@ async fn main() -> Result<()> {
         Some(Command::GenConfig(gen_config_args)) => cmd_gen_config(gen_config_args)?,
         Some(Command::Pwhash(pwhash_args)) => cmd_pwhash(pwhash_args)?,
         None => {
-            let config: Config = toml::from_str(
-                &fs::read_to_string(&args.config_file).unwrap_or_else(|err| {
-                    panic!("Could not open file at {}: {}", &args.config_file, err)
-                }),
-            )?;
+            let config: Config = Figment::new()
+                // TODO: What to do when config file does not exist?
+                .merge(Toml::file(&args.config_file))
+                .merge(Env::prefixed("RUSTICAL_").split("__"))
+                .extract()?;
 
             setup_tracing(&config.tracing);