Use 202 Accepted for SetOverrides and buffer GetOverrides response

SetOverrides writes to the object storage bucket like the ruler API,
so it should return 202 Accepted to indicate the change has been stored
Also buffer the GetOverrides JSON response so http.Error works correctly if encoding fails.

Signed-off-by: Friedrich Gonzalez <[email protected]>

Author: friedrichg

docs/guides/overrides.md

@@ -197,7 +197,7 @@ Result:
 }
 ```
 
-**Response (200 OK):**
+**Response (202 Accepted):**
 Returns success with no body.
 
 **Response (400 Bad Request):**

pkg/overrides/api.go

@@ -71,12 +71,18 @@ func (a *API) GetOverrides(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "not found", http.StatusNotFound)
 		return
 	}
-	w.Header().Set("Content-Type", "application/json")
-	if err := json.NewEncoder(w).Encode(overrides); err != nil {
+
+	// Buffer the response before writing headers so http.Error works if encoding fails
+	var buf bytes.Buffer
+	if err := json.NewEncoder(&buf).Encode(overrides); err != nil {
 		level.Error(a.logger).Log("msg", "failed to encode overrides response", "err", err)
 		http.Error(w, "Internal server error", http.StatusInternalServerError)
 		return
 	}
+	w.Header().Set("Content-Type", "application/json")
+	if _, err := w.Write(buf.Bytes()); err != nil {
+		level.Error(a.logger).Log("msg", "failed to write overrides response", "err", err)
+	}
 }
 
 // SetOverrides updates overrides for a specific tenant
@@ -122,7 +128,7 @@ func (a *API) SetOverrides(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	w.WriteHeader(http.StatusOK)
+	w.WriteHeader(http.StatusAccepted)
 }
 
 // DeleteOverrides removes tenant-specific overrides

pkg/overrides/overrides_test.go

@@ -234,7 +234,7 @@ func TestAPIEndpoints(t *testing.T) {
 			path:           "/api/v1/user-overrides",
 			tenantID:       "user789",
 			requestBody:    map[string]any{"ingestion_rate": 5000, "ruler_max_rules_per_rule_group": 10},
-			expectedStatus: http.StatusOK,
+			expectedStatus: http.StatusAccepted,
 			setupMock: func(mock *bucket.ClientMock) {
 				// Mock runtime config with allowed limits
 				runtimeConfig := `overrides:
@@ -288,7 +288,7 @@ api_allowed_limits:
 			path:           "/api/v1/user-overrides",
 			tenantID:       "user888",
 			requestBody:    map[string]any{"ingestion_rate": 8000}, // Only update ingestion_rate
-			expectedStatus: http.StatusOK,
+			expectedStatus: http.StatusAccepted,
 			setupMock: func(m *bucket.ClientMock) {
 				// Mock runtime config with existing overrides for user888
 				initialConfig := `overrides: