chore: bootstrap rust service

src/config.rs

@@ -0,0 +1,76 @@
+use std::{env, net::SocketAddr, time::Duration};
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct AppConfig {
+    pub bind_addr: SocketAddr,
+    pub pokeapi_base_url: String,
+    pub translations_base_url: String,
+    pub request_timeout: Duration,
+    pub rate_limit_per_second: f64,
+    pub rate_limit_burst: u32,
+    pub service_name: String,
+}
+
+impl AppConfig {
+    pub fn from_env() -> Result<Self, ConfigError> {
+        Ok(Self {
+            bind_addr: env_or_parse("BIND_ADDR", default_bind_addr())?,
+            pokeapi_base_url: env_or_string("POKEAPI_BASE_URL", "https://pokeapi.co/api/v2"),
+            translations_base_url: env_or_string(
+                "FUN_TRANSLATIONS_BASE_URL",
+                "https://funtranslations.mercxry.me",
+            ),
+            request_timeout: Duration::from_secs(env_or_parse("REQUEST_TIMEOUT_SECONDS", 5)?),
+            rate_limit_per_second: env_or_parse("RATE_LIMIT_PER_SECOND", 20.0)?,
+            rate_limit_burst: env_or_parse("RATE_LIMIT_BURST", 40)?,
+            service_name: env_or_string("OTEL_SERVICE_NAME", env!("CARGO_PKG_NAME")),
+        })
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum ConfigError {
+    #[error("invalid value for {name}: {source}")]
+    InvalidValue {
+        name: &'static str,
+        source: Box<dyn std::error::Error + Send + Sync>,
+    },
+}
+
+fn env_or_string(name: &'static str, default: &str) -> String {
+    env::var(name).unwrap_or_else(|_| default.to_owned())
+}
+
+fn default_bind_addr() -> SocketAddr {
+    SocketAddr::from(([0, 0, 0, 0], 5000))
+}
+
+fn env_or_parse<T>(name: &'static str, default: T) -> Result<T, ConfigError>
+where
+    T: std::str::FromStr,
+    T::Err: std::error::Error + Send + Sync + 'static,
+{
+    env::var(name).map_or_else(
+        |_| Ok(default),
+        |value| {
+            value.parse().map_err(|source| ConfigError::InvalidValue {
+                name,
+                source: Box::new(source),
+            })
+        },
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use super::AppConfig;
+
+    #[test]
+    fn default_config_is_valid_for_local_development() {
+        let config = AppConfig::from_env().expect("default env should parse");
+
+        assert_eq!(config.bind_addr.port(), 5000);
+        assert_eq!(config.pokeapi_base_url, "https://pokeapi.co/api/v2");
+        assert!((config.rate_limit_per_second - 20.0).abs() < f64::EPSILON);
+    }
+}

src/lib.rs

@@ -0,0 +1,10 @@
+#![deny(warnings)]
+#![deny(clippy::all, clippy::pedantic, clippy::nursery, clippy::cargo)]
+#![allow(clippy::missing_errors_doc, clippy::multiple_crate_versions)]
+
+pub mod config;
+
+#[must_use]
+pub const fn crate_name() -> &'static str {
+    env!("CARGO_PKG_NAME")
+}

src/main.rs

@@ -0,0 +1,11 @@
+#![deny(warnings)]
+#![deny(clippy::all, clippy::pedantic, clippy::nursery, clippy::cargo)]
+#![allow(clippy::missing_errors_doc, clippy::multiple_crate_versions)]
+
+use pokedex_api::{config::AppConfig, crate_name};
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let _config = AppConfig::from_env()?;
+    println!("{name} bootstrap complete", name = crate_name());
+    Ok(())
+}