chore: add Caddy gRPC service to retrieve Caddyfile config from machines

internal/machine/caddyconfig/controller.go

@@ -128,7 +128,7 @@ func (c *Controller) generateCaddyfile(ctx context.Context, containers []store.C
 }
 
 func (c *Controller) generateJSONConfig(containers []store.ContainerRecord) error {
-	serviceContainers := make([]api.ServiceContainer, 0, len(containers))
+	serviceContainers := make([]api.ServiceContainer, len(containers))
 	for i, cr := range containers {
 		serviceContainers[i] = cr.Container
 	}

internal/machine/caddyconfig/server.go

@@ -0,0 +1,39 @@
+package caddyconfig
+
+import (
+	"context"
+	"os"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/types/known/emptypb"
+	"google.golang.org/protobuf/types/known/timestamppb"
+
+	"github.com/psviderski/uncloud/internal/machine/api/pb"
+)
+
+// Server implements the gRPC Caddy service.
+type Server struct {
+	pb.UnimplementedCaddyServer
+	service *Service
+}
+
+func NewServer(service *Service) *Server {
+	return &Server{service: service}
+}
+
+// GetConfig retrieves the current Caddy configuration from the machine.
+func (s *Server) GetConfig(ctx context.Context, _ *emptypb.Empty) (*pb.GetCaddyConfigResponse, error) {
+	caddyfile, modifiedAt, err := s.service.Caddyfile()
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, status.Errorf(codes.NotFound, err.Error())
+		}
+		return nil, status.Errorf(codes.Internal, err.Error())
+	}
+
+	return &pb.GetCaddyConfigResponse{
+		Caddyfile:  caddyfile,
+		ModifiedAt: timestamppb.New(modifiedAt),
+	}, nil
+}

internal/machine/caddyconfig/service.go

@@ -0,0 +1,35 @@
+package caddyconfig
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+// Service provides methods to interact with the Caddy configuration on the machine.
+type Service struct {
+	configDir string
+}
+
+// NewService creates a new Service instance with the specified Caddy configuration directory.
+func NewService(configDir string) *Service {
+	return &Service{configDir: configDir}
+}
+
+// Caddyfile retrieves the current Caddy configuration (Caddyfile) from the machine's config directory.
+func (s *Service) Caddyfile() (string, time.Time, error) {
+	path := filepath.Join(s.configDir, "Caddyfile")
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("read Caddyfile from file '%s': %w", path, err)
+	}
+
+	// Get the file modification time.
+	fileInfo, err := os.Stat(path)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("get Caddyfile file info '%s': %w", path, err)
+	}
+
+	return string(content), fileInfo.ModTime(), nil
+}