[model-gateway] Simplify error response creation (#15079)

sgl-model-gateway/src/routers/error.rs

@@ -3,7 +3,20 @@ use axum::{
     response::{IntoResponse, Response},
     Json,
 };
-use serde_json::json;
+use serde::Serialize;
+
+#[derive(Serialize)]
+struct ErrorResponse<'a> {
+    error: ErrorDetail<'a>,
+}
+
+#[derive(Serialize)]
+struct ErrorDetail<'a> {
+    #[serde(rename = "type")]
+    error_type: &'static str,
+    code: &'a str,
+    message: &'a str,
+}
 
 pub const HEADER_X_SMG_ERROR_CODE: &str = "X-SMG-Error-Code";
 
@@ -47,7 +60,7 @@ pub fn create_error(
     let code_str = code.into();
     let message_str = message.into();
 
-    let mut headers = HeaderMap::new();
+    let mut headers = HeaderMap::with_capacity(1);
     headers.insert(
         HEADER_X_SMG_ERROR_CODE,
         HeaderValue::from_str(&code_str).unwrap(),
@@ -56,92 +69,21 @@ pub fn create_error(
     (
         status,
         headers,
-        Json(json!({
-            "error": {
-                "type": status_code_to_str(status),
-                "code": code_str,
-                "message": message_str,
-            }
-        })),
+        Json(ErrorResponse {
+            error: ErrorDetail {
+                error_type: status_code_to_str(status),
+                code: &code_str,
+                message: &message_str,
+            },
+        }),
     )
         .into_response()
 }
 
 fn status_code_to_str(status_code: StatusCode) -> &'static str {
-    match status_code {
-        // 1xx
-        StatusCode::CONTINUE => "continue",
-        StatusCode::SWITCHING_PROTOCOLS => "switching_protocols",
-        StatusCode::PROCESSING => "processing",
-        StatusCode::EARLY_HINTS => "early_hints",
-
-        // 2xx
-        StatusCode::OK => "ok",
-        StatusCode::CREATED => "created",
-        StatusCode::ACCEPTED => "accepted",
-        StatusCode::NON_AUTHORITATIVE_INFORMATION => "non_authoritative_information",
-        StatusCode::NO_CONTENT => "no_content",
-        StatusCode::RESET_CONTENT => "reset_content",
-        StatusCode::PARTIAL_CONTENT => "partial_content",
-        StatusCode::MULTI_STATUS => "multi_status",
-        StatusCode::ALREADY_REPORTED => "already_reported",
-        StatusCode::IM_USED => "im_used",
-
-        // 3xx
-        StatusCode::MULTIPLE_CHOICES => "multiple_choices",
-        StatusCode::MOVED_PERMANENTLY => "moved_permanently",
-        StatusCode::FOUND => "found",
-        StatusCode::SEE_OTHER => "see_other",
-        StatusCode::NOT_MODIFIED => "not_modified",
-        StatusCode::USE_PROXY => "use_proxy",
-        StatusCode::TEMPORARY_REDIRECT => "temporary_redirect",
-        StatusCode::PERMANENT_REDIRECT => "permanent_redirect",
-
-        // 4xx
-        StatusCode::BAD_REQUEST => "bad_request",
-        StatusCode::UNAUTHORIZED => "unauthorized",
-        StatusCode::PAYMENT_REQUIRED => "payment_required",
-        StatusCode::FORBIDDEN => "forbidden",
-        StatusCode::NOT_FOUND => "not_found",
-        StatusCode::METHOD_NOT_ALLOWED => "method_not_allowed",
-        StatusCode::NOT_ACCEPTABLE => "not_acceptable",
-        StatusCode::PROXY_AUTHENTICATION_REQUIRED => "proxy_authentication_required",
-        StatusCode::REQUEST_TIMEOUT => "request_timeout",
-        StatusCode::CONFLICT => "conflict",
-        StatusCode::GONE => "gone",
-        StatusCode::LENGTH_REQUIRED => "length_required",
-        StatusCode::PRECONDITION_FAILED => "precondition_failed",
-        StatusCode::PAYLOAD_TOO_LARGE => "payload_too_large",
-        StatusCode::URI_TOO_LONG => "uri_too_long",
-        StatusCode::UNSUPPORTED_MEDIA_TYPE => "unsupported_media_type",
-        StatusCode::RANGE_NOT_SATISFIABLE => "range_not_satisfiable",
-        StatusCode::EXPECTATION_FAILED => "expectation_failed",
-        StatusCode::IM_A_TEAPOT => "im_a_teapot",
-        StatusCode::MISDIRECTED_REQUEST => "misdirected_request",
-        StatusCode::UNPROCESSABLE_ENTITY => "unprocessable_entity",
-        StatusCode::LOCKED => "locked",
-        StatusCode::FAILED_DEPENDENCY => "failed_dependency",
-        StatusCode::UPGRADE_REQUIRED => "upgrade_required",
-        StatusCode::PRECONDITION_REQUIRED => "precondition_required",
-        StatusCode::TOO_MANY_REQUESTS => "too_many_requests",
-        StatusCode::REQUEST_HEADER_FIELDS_TOO_LARGE => "request_header_fields_too_large",
-        StatusCode::UNAVAILABLE_FOR_LEGAL_REASONS => "unavailable_for_legal_reasons",
-
-        // 5xx
-        StatusCode::INTERNAL_SERVER_ERROR => "internal_server_error",
-        StatusCode::NOT_IMPLEMENTED => "not_implemented",
-        StatusCode::BAD_GATEWAY => "bad_gateway",
-        StatusCode::SERVICE_UNAVAILABLE => "service_unavailable",
-        StatusCode::GATEWAY_TIMEOUT => "gateway_timeout",
-        StatusCode::HTTP_VERSION_NOT_SUPPORTED => "http_version_not_supported",
-        StatusCode::VARIANT_ALSO_NEGOTIATES => "variant_also_negotiates",
-        StatusCode::INSUFFICIENT_STORAGE => "insufficient_storage",
-        StatusCode::LOOP_DETECTED => "loop_detected",
-        StatusCode::NOT_EXTENDED => "not_extended",
-        StatusCode::NETWORK_AUTHENTICATION_REQUIRED => "network_authentication_required",
-
-        _ => "unknown_status_code",
-    }
+    status_code
+        .canonical_reason()
+        .unwrap_or("Unknown Status Code")
 }
 
 pub fn extract_error_code_from_response<B>(response: &Response<B>) -> &str {
@@ -151,38 +93,3 @@ pub fn extract_error_code_from_response<B>(response: &Response<B>) -> &str {
         .and_then(|v| v.to_str().ok())
         .unwrap_or_default()
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_internal_error_string() {
-        let response = internal_error("test_error", "Test error");
-        assert_eq!(response.status(), StatusCode::INTERNAL_SERVER_ERROR);
-    }
-
-    #[test]
-    fn test_internal_error_format() {
-        let response = internal_error("test_error", format!("Error: {}", 42));
-        assert_eq!(response.status(), StatusCode::INTERNAL_SERVER_ERROR);
-    }
-
-    #[test]
-    fn test_bad_request() {
-        let response = bad_request("invalid_input", "Invalid input");
-        assert_eq!(response.status(), StatusCode::BAD_REQUEST);
-    }
-
-    #[test]
-    fn test_not_found() {
-        let response = not_found("resource_not_found", "Resource not found");
-        assert_eq!(response.status(), StatusCode::NOT_FOUND);
-    }
-
-    #[test]
-    fn test_service_unavailable() {
-        let response = service_unavailable("no_workers", "No workers");
-        assert_eq!(response.status(), StatusCode::SERVICE_UNAVAILABLE);
-    }
-}