Add command line arguments + config parsing

Author: spacebear21

payjoin-service/Cargo.toml

@@ -20,8 +20,11 @@ default = []
 
 [dependencies]
 anyhow = "1.0"
+clap = { version = "4.5", features = ["derive", "env"] }
+config = "0.15"
 ohttp-relay = { path = "../ohttp-relay" }
 payjoin-directory = { path = "../payjoin-directory" }
+serde = { version = "1.0", features = ["derive"] }
 tokio = { version = "1.47", features = ["full"] }
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }

payjoin-service/src/cli.rs

@@ -0,0 +1,14 @@
+use std::env;
+
+use clap::Parser;
+
+#[derive(Debug, Parser)]
+#[command(
+    version = env!("CARGO_PKG_VERSION"),
+    about = "Payjoin Directory and OHTTP Relay service",
+    long_about = None,
+)]
+pub struct Cli {
+    #[arg(long, short = 'p', env = "PJ_PORT", help = "The port to bind [default: 8080]")]
+    pub port: Option<u16>,
+}

payjoin-service/src/config.rs

@@ -0,0 +1,31 @@
+use config::builder::DefaultState;
+use config::{ConfigError, File, FileFormat};
+use serde::Deserialize;
+
+use crate::cli::Cli;
+
+type Builder = config::builder::ConfigBuilder<DefaultState>;
+
+#[derive(Debug, Clone, Deserialize)]
+pub struct Config {
+    pub port: u16,
+}
+
+impl Config {
+    pub fn new(cli: &Cli) -> Result<Self, ConfigError> {
+        let mut config = config::Config::builder();
+        config = add_defaults(config, cli)?;
+
+        config = config.add_source(File::new("config.toml", FileFormat::Toml).required(false));
+
+        let built_config = config.build()?;
+
+        Ok(Config { port: built_config.get("port")? })
+    }
+}
+
+fn add_defaults(config: Builder, cli: &Cli) -> Result<Builder, ConfigError> {
+    let config = config.set_default("port", 8080)?.set_override_option("port", cli.port)?;
+
+    Ok(config)
+}

payjoin-service/src/main.rs

@@ -1,11 +1,18 @@
+use clap::Parser;
 use tracing_subscriber::filter::LevelFilter;
 use tracing_subscriber::EnvFilter;
 
+mod cli;
+mod config;
+
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     init_tracing();
 
-    todo!("Everything")
+    let cli = cli::Cli::parse();
+    let config = config::Config::new(&cli)?;
+
+    todo!("Initialize services and start server on port {}", config.port)
 }
 
 fn init_tracing() {