feat: add /spec endpoint to OAS APIs to expose OAS definitions

gateway/api_loader.go

@@ -118,6 +118,9 @@ func fixFuncPath(pathPrefix string, funcs []apidef.MiddlewareDefinition) {
 }
 
 func (gw *Gateway) generateSubRoutes(spec *APISpec, router *mux.Router, logger *logrus.Entry) {
+	// Add OAS spec endpoint for OAS APIs
+	gw.addOASSpecEndpoint(spec, router, logger)
+
 	if spec.GraphQL.GraphQLPlayground.Enabled {
 		gw.loadGraphQLPlayground(spec, router)
 	}

gateway/oas_spec_endpoint.go

@@ -0,0 +1,43 @@
+package gateway
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/gorilla/mux"
+	"github.com/sirupsen/logrus"
+)
+
+const (
+	oasSpecEndpoint = "/spec"
+)
+
+// addOASSpecEndpoint adds a /spec endpoint to OAS APIs that returns the OAS definition
+// This endpoint bypasses all middleware, including authentication, rate limiting, etc.
+func (gw *Gateway) addOASSpecEndpoint(spec *APISpec, router *mux.Router, logger *logrus.Entry) {
+	// Only add the endpoint to OAS APIs
+	if !spec.IsOAS {
+		return
+	}
+
+	logger.Debug("Adding OAS spec endpoint for API: ", spec.APIID)
+
+	// Create a direct handler for the /spec endpoint that completely bypasses middleware
+	// This is registered directly with the router, so it's processed before any middleware chain
+	router.HandleFunc(oasSpecEndpoint, func(w http.ResponseWriter, r *http.Request) {
+		// Set content type header
+		w.Header().Set("Content-Type", "application/json")
+
+		// Marshal the OAS definition to JSON
+		oasJSON, err := json.Marshal(spec.OAS)
+		if err != nil {
+			logger.WithError(err).Error("Error marshaling OAS spec to JSON")
+			http.Error(w, "Error generating OAS spec", http.StatusInternalServerError)
+			return
+		}
+
+		// Write the response
+		w.WriteHeader(http.StatusOK)
+		w.Write(oasJSON)
+	}).Methods(http.MethodGet)
+}