DiscoveryConfig: add service with rbac support (#32371)

* DiscoveryConfig: add service with rbac support

This PR adds the DiscoveryConfig service protected by RBAC rules.

A PR will follow that uses this service to expose the service in the
gRPC server.

* review pt1

lib/auth/discoveryconfig/discoveryconfigv1/service.go

@@ -0,0 +1,199 @@
+/*
+Copyright 2023 Gravitational, Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package discoveryconfigv1
+
+import (
+	"context"
+
+	"github.com/gravitational/trace"
+	"github.com/jonboulle/clockwork"
+	"github.com/sirupsen/logrus"
+	"google.golang.org/protobuf/types/known/emptypb"
+
+	discoveryconfigv1 "github.com/gravitational/teleport/api/gen/proto/go/teleport/discoveryconfig/v1"
+	"github.com/gravitational/teleport/api/types"
+	conv "github.com/gravitational/teleport/api/types/discoveryconfig/convert/v1"
+	"github.com/gravitational/teleport/lib/authz"
+	"github.com/gravitational/teleport/lib/services"
+)
+
+// ServiceConfig holds configuration options for the DiscoveryConfig gRPC service.
+type ServiceConfig struct {
+	// Logger is the logger to use.
+	Logger logrus.FieldLogger
+
+	// Authorizer is the authorizer to use.
+	Authorizer authz.Authorizer
+
+	// Backend is the backend for storing DiscoveryConfigs.
+	Backend services.DiscoveryConfigs
+
+	// Clock is the clock.
+	Clock clockwork.Clock
+}
+
+// CheckAndSetDefaults checks the ServiceConfig fields and returns an error if
+// a required param is not provided.
+// Authorizer, Cache and Backend are required params
+func (s *ServiceConfig) CheckAndSetDefaults() error {
+	if s.Authorizer == nil {
+		return trace.BadParameter("authorizer is required")
+	}
+	if s.Backend == nil {
+		return trace.BadParameter("backend is required")
+	}
+
+	if s.Logger == nil {
+		s.Logger = logrus.New().WithField(trace.Component, "discoveryconfig_crud_service")
+	}
+
+	if s.Clock == nil {
+		s.Clock = clockwork.NewRealClock()
+	}
+
+	return nil
+}
+
+// Service implements the teleport.DiscoveryConfig.v1.DiscoveryConfigService RPC service.
+type Service struct {
+	discoveryconfigv1.UnimplementedDiscoveryConfigServiceServer
+
+	log        logrus.FieldLogger
+	authorizer authz.Authorizer
+	backend    services.DiscoveryConfigs
+	clock      clockwork.Clock
+}
+
+// NewService returns a new DiscoveryConfigs gRPC service.
+func NewService(cfg ServiceConfig) (*Service, error) {
+	if err := cfg.CheckAndSetDefaults(); err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	return &Service{
+		log:        cfg.Logger,
+		authorizer: cfg.Authorizer,
+		backend:    cfg.Backend,
+		clock:      cfg.Clock,
+	}, nil
+}
+
+// ListDiscoveryConfigs returns a paginated list of all DiscoveryConfig resources.
+func (s *Service) ListDiscoveryConfigs(ctx context.Context, req *discoveryconfigv1.ListDiscoveryConfigsRequest) (*discoveryconfigv1.ListDiscoveryConfigsResponse, error) {
+	_, err := authz.AuthorizeWithVerbs(ctx, s.log, s.authorizer, true, types.KindDiscoveryConfig, types.VerbRead, types.VerbList)
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	results, nextKey, err := s.backend.ListDiscoveryConfigs(ctx, int(req.GetPageSize()), req.GetNextToken())
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	dcs := make([]*discoveryconfigv1.DiscoveryConfig, len(results))
+	for i, r := range results {
+		dcs[i] = conv.ToProto(r)
+	}
+
+	return &discoveryconfigv1.ListDiscoveryConfigsResponse{
+		DiscoveryConfigs: dcs,
+		NextKey:          nextKey,
+	}, nil
+}
+
+// GetDiscoveryConfig returns the specified DiscoveryConfig resource.
+func (s *Service) GetDiscoveryConfig(ctx context.Context, req *discoveryconfigv1.GetDiscoveryConfigRequest) (*discoveryconfigv1.DiscoveryConfig, error) {
+	_, err := authz.AuthorizeWithVerbs(ctx, s.log, s.authorizer, true, types.KindDiscoveryConfig, types.VerbRead)
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	dc, err := s.backend.GetDiscoveryConfig(ctx, req.Name)
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	return conv.ToProto(dc), nil
+}
+
+// CreateDiscoveryConfig creates a new DiscoveryConfig resource.
+func (s *Service) CreateDiscoveryConfig(ctx context.Context, req *discoveryconfigv1.CreateDiscoveryConfigRequest) (*discoveryconfigv1.DiscoveryConfig, error) {
+	_, err := authz.AuthorizeWithVerbs(ctx, s.log, s.authorizer, true, types.KindDiscoveryConfig, types.VerbCreate)
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	dc, err := conv.FromProto(req.GetDiscoveryConfig())
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	resp, err := s.backend.CreateDiscoveryConfig(ctx, dc)
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	return conv.ToProto(resp), nil
+}
+
+// UpdateDiscoveryConfig updates an existing DiscoveryConfig.
+func (s *Service) UpdateDiscoveryConfig(ctx context.Context, req *discoveryconfigv1.UpdateDiscoveryConfigRequest) (*discoveryconfigv1.DiscoveryConfig, error) {
+	_, err := authz.AuthorizeWithVerbs(ctx, s.log, s.authorizer, true, types.KindDiscoveryConfig, types.VerbUpdate)
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	dc, err := conv.FromProto(req.GetDiscoveryConfig())
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	resp, err := s.backend.UpdateDiscoveryConfig(ctx, dc)
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	return conv.ToProto(resp), nil
+}
+
+// DeleteDiscoveryConfig removes the specified DiscoveryConfig resource.
+func (s *Service) DeleteDiscoveryConfig(ctx context.Context, req *discoveryconfigv1.DeleteDiscoveryConfigRequest) (*emptypb.Empty, error) {
+	_, err := authz.AuthorizeWithVerbs(ctx, s.log, s.authorizer, true, types.KindDiscoveryConfig, types.VerbDelete)
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	if err := s.backend.DeleteDiscoveryConfig(ctx, req.GetName()); err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	return &emptypb.Empty{}, nil
+}
+
+// DeleteAllDiscoveryConfigs removes all DiscoveryConfig resources.
+func (s *Service) DeleteAllDiscoveryConfigs(ctx context.Context, _ *discoveryconfigv1.DeleteAllDiscoveryConfigsRequest) (*emptypb.Empty, error) {
+	_, err := authz.AuthorizeWithVerbs(ctx, s.log, s.authorizer, true, types.KindDiscoveryConfig, types.VerbDelete)
+	if err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	if err := s.backend.DeleteAllDiscoveryConfigs(ctx); err != nil {
+		return nil, trace.Wrap(err)
+	}
+
+	return &emptypb.Empty{}, nil
+}