feat(ai-gateway): PythonAuthClient — verify keys via the Python control plane

litellm-rust/crates/ai-gateway/src/auth/client/python.rs

@@ -0,0 +1,76 @@
+//! v0 [`KeyAuthenticator`] backed by the Python proxy.
+//!
+//! Verification is a single POST to the proxy's internal auth endpoint, authorized
+//! by a shared data-plane key. The HTTP client is built once and reused (pooled
+//! connections + TLS), with bounded connect and request timeouts so a slow proxy
+//! can never hang a request indefinitely. TLS is rustls for portable builds.
+
+use std::time::Duration;
+
+use reqwest::StatusCode;
+
+use crate::auth::{AuthError, KeyAuthenticator, UserApiKeyAuth};
+
+/// Bound how long we wait to establish a connection to the proxy.
+const CONNECT_TIMEOUT_SECS: u64 = 5;
+/// Bound the full verify round-trip. Auth must be fast; a slow proxy fails closed.
+const REQUEST_TIMEOUT_SECS: u64 = 10;
+/// Header carrying the shared data-plane secret that authorizes this gateway to
+/// the proxy's internal auth endpoint.
+const DATA_PLANE_KEY_HEADER: &str = "X-LiteLLM-Data-Plane-Key";
+
+/// Calls the Python proxy to verify virtual keys. One pooled client, reused.
+pub struct PythonAuthClient {
+    http: reqwest::Client,
+    verify_url: String,
+    data_plane_key: String,
+}
+
+impl PythonAuthClient {
+    /// Build the client with bounded timeouts and rustls TLS. Panics only if the
+    /// reqwest builder fails, which is a startup misconfiguration, not a runtime
+    /// path — acceptable to surface loudly at boot.
+    pub fn new(verify_url: String, data_plane_key: String) -> Self {
+        let http = reqwest::Client::builder()
+            .connect_timeout(Duration::from_secs(CONNECT_TIMEOUT_SECS))
+            .timeout(Duration::from_secs(REQUEST_TIMEOUT_SECS))
+            .use_rustls_tls()
+            .build()
+            .expect("failed to build auth HTTP client");
+        Self {
+            http,
+            verify_url,
+            data_plane_key,
+        }
+    }
+}
+
+#[axum::async_trait]
+impl KeyAuthenticator for PythonAuthClient {
+    async fn verify(&self, key: &str) -> Result<UserApiKeyAuth, AuthError> {
+        let response = self
+            .http
+            .post(&self.verify_url)
+            .header(DATA_PLANE_KEY_HEADER, &self.data_plane_key)
+            .json(&serde_json::json!({ "api_key": key }))
+            .send()
+            .await
+            .map_err(|err| AuthError::Upstream(err.to_string()))?;
+
+        let status = response.status();
+        if status == StatusCode::UNAUTHORIZED {
+            return Err(AuthError::Unauthorized);
+        }
+        if !status.is_success() {
+            return Err(AuthError::Upstream(format!(
+                "auth verify returned status {}",
+                status.as_u16()
+            )));
+        }
+
+        response
+            .json::<UserApiKeyAuth>()
+            .await
+            .map_err(|err| AuthError::Upstream(format!("invalid auth response: {err}")))
+    }
+}