feat: added flexible configuration system using figment

CHANGELOG.md

@@ -14,3 +14,5 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
     * subscriptions
     * episode changes
     * devices
+* Flexible configuration via a TOML config file, environment variables or CLI
+  arguments

Cargo.lock

@@ -94,6 +94,15 @@ dependencies = [
  "password-hash",
 ]
 
+[[package]]
+name = "atomic"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d818003e740b63afc82337e3160717f4f63078720a810b7b903e70a5d1d2994"
+dependencies = [
+ "bytemuck",
+]
+
 [[package]]
 name = "autocfg"
 version = "1.4.0"
@@ -246,6 +255,12 @@ version = "3.17.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1628fb46dfa0b37568d12e5edd512553eccf6a22a78e8bde00bb4aed84d5bdbf"
 
+[[package]]
+name = "bytemuck"
+version = "1.22.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6b1fc10dbac614ebc03540c9dbd60e83887fda27794998c6528f1782047d540"
+
 [[package]]
 name = "byteorder"
 version = "1.5.0"
@@ -496,6 +511,20 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "877a4ace8713b0bcf2a4e7eec82529c029f1d0619886d18145fea96c3ffe5c0f"
 
+[[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 = "fnv"
 version = "1.0.7"
@@ -727,6 +756,12 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "inlinable_string"
+version = "0.1.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c8fae54786f62fb2918dcfae3d568594e50eb9b5c25bf04371af6fe7516452fb"
+
 [[package]]
 name = "is_terminal_polyfill"
 version = "1.70.1"
@@ -899,6 +934,7 @@ dependencies = [
  "cookie",
  "diesel",
  "diesel_migrations",
+ "figment",
  "libsqlite3-sys",
  "rand",
  "serde",
@@ -948,6 +984,29 @@ dependencies = [
  "subtle",
 ]
 
+[[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 = "percent-encoding"
 version = "2.3.1"
@@ -996,6 +1055,19 @@ 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 = "quote"
 version = "1.0.38"
@@ -1443,6 +1515,15 @@ version = "1.18.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1dccffe3ce07af9386bfd29e80c0ab1a8205a2fc34e4bcd40364df902cfa8f3f"
 
+[[package]]
+name = "uncased"
+version = "0.9.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e1b88fcfe09e89d3866a5c11019378088af2d24c3fbd4f0543f96b479ec90697"
+dependencies = [
+ "version_check",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.17"
@@ -1659,6 +1740,12 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "yansi"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cfe53a6657fd280eaa890a3bc59152892ffa3e30101319d168b781ed6529b049"
+
 [[package]]
 name = "zerocopy"
 version = "0.7.35"

Cargo.toml

@@ -12,6 +12,7 @@ clap = { version = "4.5.30", features = ["derive", "env"] }
 cookie = "0.18.1"
 diesel = { version = "2.2.7", features = ["r2d2", "sqlite", "returning_clauses_for_sqlite_3_35"] }
 diesel_migrations = { version = "2.2.0", features = ["sqlite"] }
+figment = { version = "0.10.19", features = ["env", "toml"] }
 libsqlite3-sys = { version = "0.31.0", features = ["bundled"] }
 rand = "0.8.5"
 serde = { version = "1.0.218", features = ["derive"] }

README.md

@@ -11,3 +11,24 @@ Gpodder, suitable for low-power devices.
     * Devices API
     * Subscriptions API
     * Episode actions API
+
+## Configuration
+
+Otter is configurable via a TOML config file, environment variables and CLI
+arguments thanks to the [Figment](https://docs.rs/figment/latest/figment/)
+library. Each variable in the configuration file below can be provided via an
+environment variable (prefixed using `OTTER_`) or a CLI argument.
+
+```toml
+data_dir = "./data"
+domain = "127.0.0.1"
+port = 8080
+```
+
+Otter can be told to read a config variable using the `--config/-c` flag (see
+the `help` command for other useful CLI commands). Each variable needs to be
+provided either from the config file, as an environment variable (e.g.
+`OTTER_DATA_DIR`) or a CLI argument (e.g. `--data-dir`).
+
+If a variable is provided in multiple ways, environment variables overwrite
+configuration file variables, and CLI arguments overwrite both.

otter.toml

@@ -0,0 +1,3 @@
+data_dir = "./data"
+domain = "127.0.0.1"
+port = 8080

src/cli/db.rs

@@ -16,16 +16,16 @@ pub enum AddCommand {
 }
 
 impl DbCommand {
-    pub fn run(&self, cli: &super::Cli) -> u8 {
+    pub fn run(&self, config: &crate::config::Config) -> u8 {
         match self {
-            DbCommand::Add(cmd) => cmd.run(cli),
+            DbCommand::Add(cmd) => cmd.run(config),
         }
     }
 }
 
 impl AddCommand {
-    pub fn run(&self, cli: &super::Cli) -> u8 {
-        match self.run_err(cli) {
+    pub fn run(&self, config: &crate::config::Config) -> u8 {
+        match self.run_err(config) {
             Ok(()) => 0,
             Err(err) => {
                 eprintln!("An error occured: {}", err.stack());
@@ -35,8 +35,8 @@ impl AddCommand {
         }
     }
 
-    pub fn run_err(&self, cli: &super::Cli) -> DbResult<()> {
-        let pool = crate::db::initialize_db(cli.data_dir.join(crate::DB_FILENAME), false)?;
+    pub fn run_err(&self, config: &crate::config::Config) -> DbResult<()> {
+        let pool = crate::db::initialize_db(config.data_dir.join(crate::DB_FILENAME), false)?;
 
         match self {
             Self::User { username, password } => {

src/cli/mod.rs

@@ -3,36 +3,78 @@ mod serve;
 
 use std::path::PathBuf;
 
-use clap::{Parser, Subcommand};
+use clap::{Args, Parser, Subcommand};
+use figment::{
+    providers::{Env, Format, Serialized, Toml},
+    Figment,
+};
+use serde::Serialize;
 
 /// Otter is a lightweight implementation of the Gpodder API, designed to be used for small
 /// personal deployments.
 #[derive(Parser)]
 pub struct Cli {
-    #[arg(
-        long = "data",
-        default_value = "./data",
-        value_name = "DATA_DIR",
-        env = "OTTER_DATA_DIR"
-    )]
-    pub data_dir: PathBuf,
+    #[command(flatten)]
+    pub config: ClapConfig,
 
     #[command(subcommand)]
     pub cmd: Command,
 }
 
+#[derive(Serialize, Args, Clone)]
+pub struct ClapConfig {
+    #[arg(
+        short,
+        long = "config",
+        env = "OTTER_CONFIG_FILE",
+        value_name = "CONFIG_FILE"
+    )]
+    config_file: Option<PathBuf>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[arg(long = "data", value_name = "DATA_DIR")]
+    data_dir: Option<PathBuf>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[arg(short, long, value_name = "DOMAIN")]
+    domain: Option<String>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[arg(short, long, value_name = "PORT")]
+    port: Option<u16>,
+}
+
 #[derive(Subcommand)]
 pub enum Command {
-    Serve(serve::ServeCommand),
+    Serve,
     #[command(subcommand)]
     Db(db::DbCommand),
 }
 
 impl Cli {
     pub fn run(&self) -> u8 {
+        let mut figment = Figment::new();
+
+        if let Some(config_path) = &self.config.config_file {
+            figment = figment.merge(Toml::file(config_path));
+        }
+
+        let config: crate::config::Config = match figment
+            .merge(Env::prefixed("OTTER_"))
+            .merge(Serialized::defaults(self.config.clone()))
+            .extract()
+        {
+            Ok(config) => config,
+            Err(err) => {
+                eprintln!("{}", err);
+
+                return 1;
+            }
+        };
+
         match &self.cmd {
-            Command::Serve(cmd) => cmd.run(self),
-            Command::Db(cmd) => cmd.run(self),
+            Command::Serve => serve::serve(&config),
+            Command::Db(cmd) => cmd.run(&config),
         }
     }
 }

src/cli/serve.rs

@@ -1,57 +1,31 @@
-use clap::Args;
-
 use crate::{db, server};
 
-/// Run the Otter web server
-#[derive(Args)]
-pub struct ServeCommand {
-    #[arg(
-        short,
-        long,
-        default_value = "127.0.0.1",
-        value_name = "DOMAIN",
-        env = "OTTER_DOMAIN"
-    )]
-    domain: String,
+pub fn serve(config: &crate::config::Config) -> u8 {
+    tracing_subscriber::fmt::init();
 
-    #[arg(
-        short,
-        long,
-        default_value = "8080",
-        value_name = "PORT",
-        env = "OTTER_PORT"
-    )]
-    port: u16,
-}
-
-impl ServeCommand {
-    pub fn run(&self, cli: &super::Cli) -> u8 {
-        tracing_subscriber::fmt::init();
-
-        tracing::info!("Initializing database and running migrations");
-
-        let pool = db::initialize_db(cli.data_dir.join(crate::DB_FILENAME), true).unwrap();
-
-        let ctx = server::Context {
-            repo: db::SqliteRepository::from(pool),
-        };
-        let app = server::app(ctx);
-
-        let rt = tokio::runtime::Builder::new_multi_thread()
-            .enable_all()
-            .build()
-            .unwrap();
-
-        let address = format!("{}:{}", self.domain, self.port);
-        tracing::info!("Starting server on {address}");
-
-        rt.block_on(async {
-            let listener = tokio::net::TcpListener::bind(address).await.unwrap();
-            axum::serve(listener, app.into_make_service())
-                .await
-                .unwrap()
-        });
-
-        0
-    }
+    tracing::info!("Initializing database and running migrations");
+
+    let pool = db::initialize_db(config.data_dir.join(crate::DB_FILENAME), true).unwrap();
+
+    let ctx = server::Context {
+        repo: db::SqliteRepository::from(pool),
+    };
+    let app = server::app(ctx);
+
+    let rt = tokio::runtime::Builder::new_multi_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+
+    let address = format!("{}:{}", config.domain, config.port);
+    tracing::info!("Starting server on {address}");
+
+    rt.block_on(async {
+        let listener = tokio::net::TcpListener::bind(address).await.unwrap();
+        axum::serve(listener, app.into_make_service())
+            .await
+            .unwrap()
+    });
+
+    0
 }

src/config.rs

@@ -0,0 +1,25 @@
+use std::path::PathBuf;
+
+use serde::Deserialize;
+
+#[derive(Deserialize)]
+pub struct Config {
+    #[serde(default = "default_data_dir")]
+    pub data_dir: PathBuf,
+    #[serde(default = "default_domain")]
+    pub domain: String,
+    #[serde(default = "default_port")]
+    pub port: u16,
+}
+
+fn default_data_dir() -> PathBuf {
+    PathBuf::from("./data")
+}
+
+fn default_domain() -> String {
+    "127.0.0.1".to_string()
+}
+
+fn default_port() -> u16 {
+    8080
+}

src/main.rs

@@ -1,4 +1,5 @@
 mod cli;
+mod config;
 mod db;
 mod gpodder;
 mod server;

src/server/gpodder/mod.rs

@@ -11,10 +11,7 @@ use axum::{
     RequestExt, Router,
 };
 use axum_extra::{
-    extract::{
-        cookie::{Cookie, Expiration},
-        CookieJar,
-    },
+    extract::{cookie::Cookie, CookieJar},
     headers::{authorization::Basic, Authorization},
     TypedHeader,
 };