config: simplify runtime environment model

apps/mcp-server/src/main.rs

@@ -7,6 +7,7 @@ use std::{env, net::SocketAddr, time::Duration};
 
 use crank_registry::PostgresRegistry;
 use crank_runtime::SecretCrypto;
+use sqlx::postgres::PgConnectOptions;
 use tokio::net::TcpListener;
 use tracing::info;
 
@@ -21,18 +22,17 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         )
         .init();
 
-    let database_url = env::var("CRANK_DATABASE_URL")?;
     let bind_addr = env::var("CRANK_MCP_BIND").unwrap_or_else(|_| "0.0.0.0:3002".into());
-    let public_base_url = env::var("CRANK_PUBLIC_BASE_URL").ok();
+    let base_url = env::var("CRANK_BASE_URL").ok();
     let refresh_interval = env::var("CRANK_MCP_REFRESH_MS")
         .ok()
         .and_then(|value| value.parse::<u64>().ok())
         .map(Duration::from_millis)
         .unwrap_or_else(|| Duration::from_secs(5));
     let socket_addr: SocketAddr = bind_addr.parse()?;
-    let registry = PostgresRegistry::connect(&database_url).await?;
+    let registry = PostgresRegistry::connect_with_options(database_options_from_env()?).await?;
     let secret_crypto = SecretCrypto::new(&env::var("CRANK_MASTER_KEY")?)?;
-    let app = build_app(registry, refresh_interval, public_base_url, secret_crypto);
+    let app = build_app(registry, refresh_interval, base_url, secret_crypto);
     let listener = TcpListener::bind(socket_addr).await?;
 
     info!("mcp-server listening on {}", socket_addr);
@@ -42,6 +42,28 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     Ok(())
 }
 
+fn database_options_from_env() -> Result<PgConnectOptions, Box<dyn std::error::Error>> {
+    if let Ok(database_url) = env::var("CRANK_DATABASE_URL") {
+        return Ok(database_url.parse::<PgConnectOptions>()?);
+    }
+
+    let host = env::var("POSTGRES_HOST").unwrap_or_else(|_| "postgres".into());
+    let port = env::var("POSTGRES_PORT")
+        .ok()
+        .and_then(|value| value.parse::<u16>().ok())
+        .unwrap_or(5432);
+    let database = env::var("POSTGRES_DB").unwrap_or_else(|_| "crank".into());
+    let username = env::var("POSTGRES_USER").unwrap_or_else(|_| "crank".into());
+    let password = env::var("POSTGRES_PASSWORD").unwrap_or_else(|_| "crank".into());
+
+    Ok(PgConnectOptions::new()
+        .host(&host)
+        .port(port)
+        .database(&database)
+        .username(&username)
+        .password(&password))
+}
+
 #[cfg(test)]
 mod tests {
     use std::{