Chore: Add basic admission handlers for registered API services (#89824)

pkg/promlib/admission_handler.go

@@ -0,0 +1,77 @@
+package promlib
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+var (
+	_ backend.AdmissionHandler = (*Service)(nil)
+)
+
+// ValidateAdmission implements backend.AdmissionHandler.
+func (s *Service) ValidateAdmission(ctx context.Context, req *backend.AdmissionRequest) (*backend.ValidationResponse, error) {
+	rsp, err := s.MutateAdmission(ctx, req)
+	if rsp != nil {
+		return &backend.ValidationResponse{
+			Allowed:  rsp.Allowed,
+			Result:   rsp.Result,
+			Warnings: rsp.Warnings,
+		}, err
+	}
+	return nil, err
+}
+
+// MutateAdmission implements backend.AdmissionHandler.
+func (s *Service) MutateAdmission(ctx context.Context, req *backend.AdmissionRequest) (*backend.MutationResponse, error) {
+	expected := (&backend.DataSourceInstanceSettings{}).GVK()
+	if req.Kind.Kind != expected.Kind && req.Kind.Group != expected.Group {
+		return getBadRequest("expected DataSourceInstanceSettings protobuf payload"), nil
+	}
+
+	// Convert the payload from protobuf to an SDK struct
+	settings, err := backend.DataSourceInstanceSettingsFromProto(req.ObjectBytes, "")
+	if err != nil {
+		return nil, err
+	}
+	if settings == nil {
+		return getBadRequest("missing datasource settings"), nil
+	}
+
+	switch settings.APIVersion {
+	case "", "v0alpha1":
+		// OK!
+	default:
+		return getBadRequest(fmt.Sprintf("expected apiVersion: v0alpha1, found: %s", settings.APIVersion)), nil
+	}
+	if settings.URL != "" {
+		return getBadRequest("unsupported URL value"), nil
+	}
+
+	pb, err := backend.DataSourceInstanceSettingsToProtoBytes(settings)
+	return &backend.MutationResponse{
+		Allowed:     true,
+		ObjectBytes: pb,
+	}, err
+}
+
+// ConvertObject implements backend.AdmissionHandler.
+func (s *Service) ConvertObject(ctx context.Context, req *backend.ConversionRequest) (*backend.ConversionResponse, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+
+func getBadRequest(msg string) *backend.MutationResponse {
+	return &backend.MutationResponse{
+		Allowed: false,
+		Result: &backend.StatusResult{
+			Status:  "Failure",
+			Message: msg,
+			Reason:  string(metav1.StatusReasonBadRequest),
+			Code:    http.StatusBadRequest,
+		},
+	}
+}

pkg/registry/apis/datasource/register.go

@@ -67,6 +67,8 @@ func RegisterAPIService(
 	var err error
 	var builder *DataSourceAPIBuilder
 	all := pluginStore.Plugins(context.Background(), plugins.TypeDataSource)
+	// ATTENTION: Adding a datasource here requires the plugin to implement
+	// an AdmissionHandler to validate the datasource settings.
 	ids := []string{
 		"grafana-testdata-datasource",
 		"prometheus",

pkg/tsdb/graphite/admission_handler.go

@@ -0,0 +1,77 @@
+package graphite
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+var (
+	_ backend.AdmissionHandler = (*Service)(nil)
+)
+
+// ValidateAdmission implements backend.AdmissionHandler.
+func (s *Service) ValidateAdmission(ctx context.Context, req *backend.AdmissionRequest) (*backend.ValidationResponse, error) {
+	rsp, err := s.MutateAdmission(ctx, req)
+	if rsp != nil {
+		return &backend.ValidationResponse{
+			Allowed:  rsp.Allowed,
+			Result:   rsp.Result,
+			Warnings: rsp.Warnings,
+		}, err
+	}
+	return nil, err
+}
+
+// MutateAdmission implements backend.AdmissionHandler.
+func (s *Service) MutateAdmission(ctx context.Context, req *backend.AdmissionRequest) (*backend.MutationResponse, error) {
+	expected := (&backend.DataSourceInstanceSettings{}).GVK()
+	if req.Kind.Kind != expected.Kind && req.Kind.Group != expected.Group {
+		return getBadRequest("expected DataSourceInstanceSettings protobuf payload"), nil
+	}
+
+	// Convert the payload from protobuf to an SDK struct
+	settings, err := backend.DataSourceInstanceSettingsFromProto(req.ObjectBytes, "")
+	if err != nil {
+		return nil, err
+	}
+	if settings == nil {
+		return getBadRequest("missing datasource settings"), nil
+	}
+
+	switch settings.APIVersion {
+	case "", "v0alpha1":
+		// OK!
+	default:
+		return getBadRequest(fmt.Sprintf("expected apiVersion: v0alpha1, found: %s", settings.APIVersion)), nil
+	}
+	if settings.URL != "" {
+		return getBadRequest("unsupported URL value"), nil
+	}
+
+	pb, err := backend.DataSourceInstanceSettingsToProtoBytes(settings)
+	return &backend.MutationResponse{
+		Allowed:     true,
+		ObjectBytes: pb,
+	}, err
+}
+
+// ConvertObject implements backend.AdmissionHandler.
+func (s *Service) ConvertObject(ctx context.Context, req *backend.ConversionRequest) (*backend.ConversionResponse, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+
+func getBadRequest(msg string) *backend.MutationResponse {
+	return &backend.MutationResponse{
+		Allowed: false,
+		Result: &backend.StatusResult{
+			Status:  "Failure",
+			Message: msg,
+			Reason:  string(metav1.StatusReasonBadRequest),
+			Code:    http.StatusBadRequest,
+		},
+	}
+}