Configuração & Ambiente

use clap::Parser;
use figment::{providers::{Env, Format, Serialized, Toml}, Figment};
use serde::Deserialize;
 
#[derive(Parser)]
struct Cli {
    #[arg(short, long)]
    config: Option<std::path::PathBuf>,
    #[arg(long)]
    port: Option<u16>,
}
 
#[derive(Debug, Deserialize)]
struct Settings {
    port: u16,
    host: String,
}
 
fn load(cli: &Cli) -> anyhow::Result<Settings> {
    let mut figment = Figment::new()
        .merge(Serialized::defaults(Settings { port: 8080, host: "127.0.0.1".into() }))
        .merge(Toml::file(cli.config.clone().unwrap_or_else(|| "config.toml".into())))
        .merge(Env::prefixed("APP_").split("_"));
    if let Some(port) = cli.port {
        figment = figment.merge(Serialized::from(("port", port)));
    }
    Ok(figment.extract()?)
}

use clap::Parser;
use serde::Deserialize;
use std::path::PathBuf;
 
#[derive(Parser)]
#[command(name = "worker")]
struct Cli {
    /// Caminho para o config TOML (padrão: ./worker.toml)
    #[arg(short, long, env = "WORKER_CONFIG")]
    config: Option<PathBuf>,
 
    /// Substituir nível de log
    #[arg(long, env = "RUST_LOG")]
    log_level: Option<String>,
 
    /// Substituir concorrência (prevalece sobre o arquivo de config)
    #[arg(long)]
    jobs: Option<usize>,
}
 
#[derive(Debug, Deserialize)]
struct FileConfig {
    jobs: usize,
    queue_url: String,
}
 
fn main() -> anyhow::Result<()> {
    let cli = Cli::parse();
    let path = cli.config.unwrap_or_else(|| PathBuf::from("worker.toml"));
    let file: FileConfig = toml::from_str(&std::fs::read_to_string(&path)?)?;
    let jobs = cli.jobs.unwrap_or(file.jobs);
    eprintln!("executando com {jobs} jobs em {}", file.queue_url);
    Ok(())
}

// Nunca leia segredos de arquivos de configuração commitados no git
let api_key = std::env::var("API_KEY")
    .context("defina API_KEY no ambiente")?;