better rest mapper init

On-behalf-of: @SAP [email protected]
Signed-off-by: Artem Shcherbatiuk <[email protected]>

Author: vertex451

gateway/manager/targetcluster/cluster.go

@@ -19,7 +19,7 @@ import (
 	"github.com/openmfp/kubernetes-graphql-gateway/gateway/schema"
 
 	// for REST mapper
-	apiutil "sigs.k8s.io/controller-runtime/pkg/client/apiutil"
+	meta "k8s.io/apimachinery/pkg/api/meta"
 )
 
 // FileData represents the data extracted from a schema file
@@ -56,6 +56,7 @@ type TargetCluster struct {
 	name          string
 	client        client.WithWatch
 	restCfg       *rest.Config
+	restMapper    meta.RESTMapper
 	handler       *GraphQLHandler
 	graphqlServer *GraphQLServer
 	log           *logger.Logger
@@ -68,16 +69,18 @@ func NewTargetCluster(
 	log *logger.Logger,
 	appCfg appConfig.Config,
 	roundTripperFactory func(http.RoundTripper, rest.TLSClientConfig) http.RoundTripper,
+	restMapper meta.RESTMapper,
 ) (*TargetCluster, error) {
 	fileData, err := readSchemaFile(schemaFilePath)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read schema file: %w", err)
 	}
 
 	cluster := &TargetCluster{
-		appCfg: appCfg,
-		name:   name,
-		log:    log,
+		appCfg:     appCfg,
+		name:       name,
+		log:        log,
+		restMapper: restMapper,
 	}
 
 	// Connect to cluster - use metadata if available, otherwise fall back to standard config
@@ -133,6 +136,11 @@ func (tc *TargetCluster) connect(appCfg appConfig.Config, metadata *ClusterMetad
 		return fmt.Errorf("failed to create cluster client: %w", err)
 	}
 
+	// Create RESTMapper if not provided
+	if tc.restMapper == nil {
+		return fmt.Errorf("rest mapper is required")
+	}
+
 	return nil
 }
 
@@ -168,25 +176,15 @@ func buildConfigFromMetadata(metadata *ClusterMetadata, log *logger.Logger) (*re
 }
 
 // createHandler creates the GraphQL schema and handler
-func (tc *TargetCluster) createHandler(definitions map[string]interface{}, appCfg appConfig.Config) error {
+func (tc *TargetCluster) createHandler(definitions map[string]any, appCfg appConfig.Config) error {
 	// Convert definitions to spec format
 	specDefs, err := convertToSpecDefinitions(definitions)
 	if err != nil {
 		return fmt.Errorf("failed to convert definitions: %w", err)
 	}
 
-	// Build RESTMapper for this cluster (used by relation resolver)
-	httpClient, err := rest.HTTPClientFor(tc.restCfg)
-	if err != nil {
-		return fmt.Errorf("failed to create HTTP client: %w", err)
-	}
-	restMapper, err := apiutil.NewDynamicRESTMapper(tc.restCfg, httpClient)
-	if err != nil {
-		return fmt.Errorf("failed to create REST mapper: %w", err)
-	}
-
 	// Create resolver
-	resolverProvider := resolver.New(tc.log, tc.client, restMapper)
+	resolverProvider := resolver.New(tc.log, tc.client, tc.restMapper)
 
 	// Create schema gateway
 	schemaGateway, err := schema.New(tc.log, specDefs, resolverProvider)
@@ -261,7 +259,7 @@ func readSchemaFile(filePath string) (*FileData, error) {
 }
 
 // convertToSpecDefinitions converts map definitions to go-openapi spec format
-func convertToSpecDefinitions(definitions map[string]interface{}) (spec.Definitions, error) {
+func convertToSpecDefinitions(definitions map[string]any) (spec.Definitions, error) {
 	data, err := json.Marshal(definitions)
 	if err != nil {
 		return nil, fmt.Errorf("failed to marshal definitions: %w", err)

gateway/manager/targetcluster/registry.go

@@ -14,6 +14,9 @@ import (
 	appConfig "github.com/openmfp/kubernetes-graphql-gateway/common/config"
 	"github.com/openmfp/kubernetes-graphql-gateway/gateway/manager/roundtripper"
 	"k8s.io/client-go/rest"
+
+	// mapper
+	apiutil "sigs.k8s.io/controller-runtime/pkg/client/apiutil"
 )
 
 // contextKey is a custom type for context keys to avoid collisions
@@ -61,8 +64,32 @@ func (cr *ClusterRegistry) LoadCluster(schemaFilePath string) error {
 		Str("file", schemaFilePath).
 		Msg("Loading target cluster")
 
+	// Build RESTMapper upfront to avoid hidden init
+	fileData, err := readSchemaFile(schemaFilePath)
+	if err != nil {
+		return fmt.Errorf("failed to read schema file: %w", err)
+	}
+	if fileData.ClusterMetadata == nil {
+		return fmt.Errorf("cluster %s requires cluster metadata in schema file", name)
+	}
+	cfg, err := buildConfigFromMetadata(fileData.ClusterMetadata, cr.log)
+	if err != nil {
+		return fmt.Errorf("failed to build config from metadata: %w", err)
+	}
+	if cr.roundTripperFactory != nil {
+		cfg.Wrap(func(rt http.RoundTripper) http.RoundTripper { return cr.roundTripperFactory(rt, cfg.TLSClientConfig) })
+	}
+	httpClient, err := rest.HTTPClientFor(cfg)
+	if err != nil {
+		return fmt.Errorf("failed to create HTTP client: %w", err)
+	}
+	restMapper, err := apiutil.NewDynamicRESTMapper(cfg, httpClient)
+	if err != nil {
+		return fmt.Errorf("failed to create REST mapper: %w", err)
+	}
+
 	// Create or update cluster
-	cluster, err := NewTargetCluster(name, schemaFilePath, cr.log, cr.appCfg, cr.roundTripperFactory)
+	cluster, err := NewTargetCluster(name, schemaFilePath, cr.log, cr.appCfg, cr.roundTripperFactory, restMapper)
 	if err != nil {
 		return fmt.Errorf("failed to create target cluster %s: %w", name, err)
 	}