Feature: External driver plugin system and update Makefile

Makefile

@@ -243,18 +243,48 @@ endif
 # calls the native resolver library and not the simplistic version in the Go library.
 ENVS__output/bin/limactl$(exe) = CGO_ENABLED=1 GOOS="$(GOOS)" GOARCH="$(GOARCH)" CC="$(CC)"
 
+LIMACTL_DRIVER_TAGS :=
+ifneq (,$(findstring vz,$(ADDITIONAL_DRIVERS)))
+LIMACTL_DRIVER_TAGS += external_vz
+endif
+ifneq (,$(findstring qemu,$(ADDITIONAL_DRIVERS)))
+LIMACTL_DRIVER_TAGS += external_qemu
+endif
+ifneq (,$(findstring wsl2,$(ADDITIONAL_DRIVERS)))
+LIMACTL_DRIVER_TAGS += external_wsl2
+endif
+
+GO_BUILDTAGS ?=
+GO_BUILDTAGS_LIMACTL := $(strip $(GO_BUILDTAGS) $(LIMACTL_DRIVER_TAGS))
+
 _output/bin/limactl$(exe): $(LIMACTL_DEPS) $$(call force_build,$$@)
-# If the previous cross-compilation was for GOOS=windows, limactl.exe might still be present.
 ifneq ($(GOOS),windows) #
 	@rm -rf _output/bin/limactl.exe
 else
 	@rm -rf _output/bin/limactl
 endif
-	$(ENVS_$@) $(GO_BUILD) -o $@ ./cmd/limactl
+	$(ENVS_$@) $(GO_BUILD) -tags '$(GO_BUILDTAGS_LIMACTL)' -o $@ ./cmd/limactl
 ifeq ($(GOOS),darwin)
 	codesign -f -v --entitlements vz.entitlements -s - $@
 endif
 
+DRIVER_INSTALL_DIR := _output/libexec/lima
+
+.PHONY: additional-drivers
+additional-drivers:
+	@mkdir -p $(DRIVER_INSTALL_DIR)
+	@for drv in $(ADDITIONAL_DRIVERS); do \
+		echo "Building $$drv as external"; \
+		if [ "$(GOOS)" = "windows" ]; then \
+			$(GO_BUILD) -o $(DRIVER_INSTALL_DIR)/lima-driver-$$drv.exe ./cmd/lima-driver-$$drv; \
+		else \
+			$(GO_BUILD) -o $(DRIVER_INSTALL_DIR)/lima-driver-$$drv ./cmd/lima-driver-$$drv; \
+			fi; \
+		if [ "$$drv" = "vz" ] && [ "$(GOOS)" = "darwin" ]; then \
+			codesign -f -v --entitlements vz.entitlements -s - $(DRIVER_INSTALL_DIR)/lima-driver-vz; \
+		fi; \
+	done
+
 LIMA_CMDS = $(sort lima lima$(bat)) # $(sort ...) deduplicates the list
 LIMA_DEPS = $(addprefix _output/bin/,$(LIMA_CMDS))
 lima: $(LIMA_DEPS)

cmd/lima-driver-qemu/main.go

@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: Copyright The Lima Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package main
+
+import (
+	"github.com/lima-vm/lima/pkg/driver/external/server"
+	"github.com/lima-vm/lima/pkg/driver/qemu"
+)
+
+// To be used as an external driver for Lima.
+func main() {
+	server.Serve(qemu.New())
+}

cmd/lima-driver-vz/main_darwin.go

@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: Copyright The Lima Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package main
+
+import (
+	"github.com/lima-vm/lima/pkg/driver/external/server"
+	"github.com/lima-vm/lima/pkg/driver/vz"
+)
+
+// To be used as an external driver for Lima.
+func main() {
+	server.Serve(vz.New())
+}

cmd/lima-driver-wsl2/main_windows.go

@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: Copyright The Lima Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package main
+
+import (
+	"github.com/lima-vm/lima/pkg/driver/external/server"
+	"github.com/lima-vm/lima/pkg/driver/wsl2"
+)
+
+// To be used as an external driver for Lima.
+func main() {
+	server.Serve(wsl2.New())
+}

cmd/limactl/main.go

@@ -16,6 +16,7 @@ import (
 	"github.com/spf13/cobra"
 
 	"github.com/lima-vm/lima/pkg/debugutil"
+	"github.com/lima-vm/lima/pkg/driver/external/server"
 	"github.com/lima-vm/lima/pkg/fsutil"
 	"github.com/lima-vm/lima/pkg/osutil"
 	"github.com/lima-vm/lima/pkg/store/dirnames"
@@ -43,6 +44,8 @@ func main() {
 		handleExitCoder(err)
 		logrus.Fatal(err)
 	}
+
+	server.StopAllExternalDrivers()
 }
 
 func newApp() *cobra.Command {

pkg/driver/external/client/client.go

@@ -0,0 +1,49 @@
+// SPDX-FileCopyrightText: Copyright The Lima Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package client
+
+import (
+	"context"
+	"net"
+
+	"github.com/sirupsen/logrus"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+
+	pb "github.com/lima-vm/lima/pkg/driver/external"
+)
+
+type DriverClient struct {
+	socketPath string
+	Conn       *grpc.ClientConn
+	DriverSvc  pb.DriverClient
+	logger     *logrus.Logger
+}
+
+func NewDriverClient(socketPath string, logger *logrus.Logger) (*DriverClient, error) {
+	opts := []grpc.DialOption{
+		grpc.WithDefaultCallOptions(grpc.MaxCallRecvMsgSize(16 << 20)),
+		grpc.WithDefaultCallOptions(grpc.MaxCallSendMsgSize(16 << 20)),
+		grpc.WithContextDialer(func(_ context.Context, _ string) (net.Conn, error) {
+			return net.Dial("unix", socketPath)
+		}),
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+	}
+
+	//nolint:staticcheck // grpc.Dial is used for compatibility reasons
+	conn, err := grpc.Dial("unix://"+socketPath, opts...)
+	if err != nil {
+		logger.Errorf("failed to dial gRPC driver client connection: %v", err)
+		return nil, err
+	}
+
+	driverSvc := pb.NewDriverClient(conn)
+
+	return &DriverClient{
+		socketPath: socketPath,
+		Conn:       conn,
+		DriverSvc:  driverSvc,
+		logger:     logger,
+	}, nil
+}