K8s: Refactor config/options for aggregation (#81739)

pkg/services/apiserver/builder/request_handler.go

@@ -0,0 +1,168 @@
+package builder
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/gorilla/mux"
+	restclient "k8s.io/client-go/rest"
+	"k8s.io/kube-openapi/pkg/spec3"
+	"k8s.io/kube-openapi/pkg/validation/spec"
+
+	"github.com/grafana/grafana/pkg/setting"
+)
+
+type requestHandler struct {
+	router *mux.Router
+}
+
+func getAPIHandler(delegateHandler http.Handler, restConfig *restclient.Config, builders []APIGroupBuilder) (http.Handler, error) {
+	useful := false // only true if any routes exist anywhere
+	router := mux.NewRouter()
+
+	for _, builder := range builders {
+		routes := builder.GetAPIRoutes()
+		if routes == nil {
+			continue
+		}
+
+		gv := builder.GetGroupVersion()
+		prefix := "/apis/" + gv.String()
+
+		// Root handlers
+		var sub *mux.Router
+		for _, route := range routes.Root {
+			if sub == nil {
+				sub = router.PathPrefix(prefix).Subrouter()
+				sub.MethodNotAllowedHandler = &methodNotAllowedHandler{}
+			}
+
+			useful = true
+			methods, err := methodsFromSpec(route.Path, route.Spec)
+			if err != nil {
+				return nil, err
+			}
+			sub.HandleFunc("/"+route.Path, route.Handler).
+				Methods(methods...)
+		}
+
+		// Namespace handlers
+		sub = nil
+		prefix += "/namespaces/{namespace}"
+		for _, route := range routes.Namespace {
+			if sub == nil {
+				sub = router.PathPrefix(prefix).Subrouter()
+				sub.MethodNotAllowedHandler = &methodNotAllowedHandler{}
+			}
+
+			useful = true
+			methods, err := methodsFromSpec(route.Path, route.Spec)
+			if err != nil {
+				return nil, err
+			}
+			sub.HandleFunc("/"+route.Path, route.Handler).
+				Methods(methods...)
+		}
+	}
+
+	if !useful {
+		return delegateHandler, nil
+	}
+
+	// Per Gorilla Mux issue here: https://github.com/gorilla/mux/issues/616#issuecomment-798807509
+	// default handler must come last
+	router.PathPrefix("/").Handler(delegateHandler)
+
+	return &requestHandler{
+		router: router,
+	}, nil
+}
+
+func (h *requestHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	h.router.ServeHTTP(w, req)
+}
+
+func methodsFromSpec(slug string, props *spec3.PathProps) ([]string, error) {
+	if props == nil {
+		return []string{"GET", "POST", "PUT", "PATCH", "DELETE"}, nil
+	}
+
+	methods := make([]string, 0)
+	if props.Get != nil {
+		methods = append(methods, "GET")
+	}
+	if props.Post != nil {
+		methods = append(methods, "POST")
+	}
+	if props.Put != nil {
+		methods = append(methods, "PUT")
+	}
+	if props.Patch != nil {
+		methods = append(methods, "PATCH")
+	}
+	if props.Delete != nil {
+		methods = append(methods, "DELETE")
+	}
+
+	if len(methods) == 0 {
+		return nil, fmt.Errorf("invalid OpenAPI Spec for slug=%s without any methods in PathProps", slug)
+	}
+
+	return methods, nil
+}
+
+type methodNotAllowedHandler struct{}
+
+func (h *methodNotAllowedHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	w.WriteHeader(405) // method not allowed
+}
+
+// Modify the the OpenAPI spec to include the additional routes.
+// Currently this requires: https://github.com/kubernetes/kube-openapi/pull/420
+// In future k8s release, the hook will use Config3 rather than the same hook for both v2 and v3
+func getOpenAPIPostProcessor(builders []APIGroupBuilder) func(*spec3.OpenAPI) (*spec3.OpenAPI, error) {
+	return func(s *spec3.OpenAPI) (*spec3.OpenAPI, error) {
+		if s.Paths == nil {
+			return s, nil
+		}
+		for _, b := range builders {
+			routes := b.GetAPIRoutes()
+			gv := b.GetGroupVersion()
+			prefix := "/apis/" + gv.String() + "/"
+			if s.Paths.Paths[prefix] != nil {
+				copy := spec3.OpenAPI{
+					Version: s.Version,
+					Info: &spec.Info{
+						InfoProps: spec.InfoProps{
+							Title:   gv.String(),
+							Version: setting.BuildVersion,
+						},
+					},
+					Components:   s.Components,
+					ExternalDocs: s.ExternalDocs,
+					Servers:      s.Servers,
+					Paths:        s.Paths,
+				}
+
+				if routes == nil {
+					routes = &APIRoutes{}
+				}
+
+				for _, route := range routes.Root {
+					copy.Paths.Paths[prefix+route.Path] = &spec3.Path{
+						PathProps: *route.Spec,
+					}
+				}
+
+				for _, route := range routes.Namespace {
+					copy.Paths.Paths[prefix+"namespaces/{namespace}/"+route.Path] = &spec3.Path{
+						PathProps: *route.Spec,
+					}
+				}
+
+				return &copy, nil
+			}
+		}
+		return s, nil
+	}
+}