feature/drive: start factoring out Taildrive, add ts_omit_drive build tag

As of this commit (per the issue), the Taildrive code remains where it
was, but in new files that are protected by the new ts_omit_drive
build tag. Future commits will move it.

Updates #17058

Change-Id: Idf0a51db59e41ae8da6ea2b11d238aefc48b219e
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscale/cli/cli.go

@@ -210,6 +210,7 @@ func noDupFlagify(c *ffcli.Command) {
 var fileCmd func() *ffcli.Command
 var sysPolicyCmd func() *ffcli.Command
 var maybeWebCmd func() *ffcli.Command
+var maybeDriveCmd func() *ffcli.Command
 
 func newRootCmd() *ffcli.Command {
 	rootfs := newFlagSet("tailscale")
@@ -262,7 +263,7 @@ change in the future.
 			updateCmd,
 			whoisCmd,
 			debugCmd(),
-			driveCmd,
+			nilOrCall(maybeDriveCmd),
 			idTokenCmd,
 			configureHostCmd(),
 			systrayCmd,

cmd/tailscale/cli/drive.go

@@ -1,6 +1,8 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
+//go:build !ts_omit_drive
+
 package cli
 
 import (
@@ -20,43 +22,49 @@ const (
 	driveListUsage    = "tailscale drive list"
 )
 
-var driveCmd = &ffcli.Command{
-	Name:      "drive",
-	ShortHelp: "Share a directory with your tailnet",
-	ShortUsage: strings.Join([]string{
-		driveShareUsage,
-		driveRenameUsage,
-		driveUnshareUsage,
-		driveListUsage,
-	}, "\n"),
-	LongHelp:  buildShareLongHelp(),
-	UsageFunc: usageFuncNoDefaultValues,
-	Subcommands: []*ffcli.Command{
-		{
-			Name:       "share",
-			ShortUsage: driveShareUsage,
-			Exec:       runDriveShare,
-			ShortHelp:  "[ALPHA] Create or modify a share",
+func init() {
+	maybeDriveCmd = driveCmd
+}
+
+func driveCmd() *ffcli.Command {
+	return &ffcli.Command{
+		Name:      "drive",
+		ShortHelp: "Share a directory with your tailnet",
+		ShortUsage: strings.Join([]string{
+			driveShareUsage,
+			driveRenameUsage,
+			driveUnshareUsage,
+			driveListUsage,
+		}, "\n"),
+		LongHelp:  buildShareLongHelp(),
+		UsageFunc: usageFuncNoDefaultValues,
+		Subcommands: []*ffcli.Command{
+			{
+				Name:       "share",
+				ShortUsage: driveShareUsage,
+				Exec:       runDriveShare,
+				ShortHelp:  "[ALPHA] Create or modify a share",
+			},
+			{
+				Name:       "rename",
+				ShortUsage: driveRenameUsage,
+				ShortHelp:  "[ALPHA] Rename a share",
+				Exec:       runDriveRename,
+			},
+			{
+				Name:       "unshare",
+				ShortUsage: driveUnshareUsage,
+				ShortHelp:  "[ALPHA] Remove a share",
+				Exec:       runDriveUnshare,
+			},
+			{
+				Name:       "list",
+				ShortUsage: driveListUsage,
+				ShortHelp:  "[ALPHA] List current shares",
+				Exec:       runDriveList,
+			},
 		},
-		{
-			Name:       "rename",
-			ShortUsage: driveRenameUsage,
-			ShortHelp:  "[ALPHA] Rename a share",
-			Exec:       runDriveRename,
-		},
-		{
-			Name:       "unshare",
-			ShortUsage: driveUnshareUsage,
-			ShortHelp:  "[ALPHA] Remove a share",
-			Exec:       runDriveUnshare,
-		},
-		{
-			Name:       "list",
-			ShortUsage: driveListUsage,
-			ShortHelp:  "[ALPHA] List current shares",
-			Exec:       runDriveList,
-		},
-	},
+	}
 }
 
 // runDriveShare is the entry point for the "tailscale drive share" command.

cmd/tailscaled/depaware.txt

@@ -274,6 +274,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/feature                                        from tailscale.com/feature/wakeonlan+
         tailscale.com/feature/capture                                from tailscale.com/feature/condregister
         tailscale.com/feature/condregister                           from tailscale.com/cmd/tailscaled
+        tailscale.com/feature/drive                                  from tailscale.com/feature/condregister
         tailscale.com/feature/relayserver                            from tailscale.com/feature/condregister
         tailscale.com/feature/syspolicy                              from tailscale.com/feature/condregister+
         tailscale.com/feature/taildrop                               from tailscale.com/feature/condregister

cmd/tailscaled/deps_test.go

@@ -61,3 +61,19 @@ func TestOmitReflectThings(t *testing.T) {
 		},
 	}.Check(t)
 }
+
+func TestOmitDrive(t *testing.T) {
+	deptest.DepChecker{
+		GOOS:   "linux",
+		GOARCH: "amd64",
+		Tags:   "ts_omit_drive,ts_include_cli",
+		OnDep: func(dep string) {
+			if strings.Contains(dep, "driveimpl") {
+				t.Errorf("unexpected dep with ts_omit_drive: %q", dep)
+			}
+			if strings.Contains(dep, "webdav") {
+				t.Errorf("unexpected dep with ts_omit_drive: %q", dep)
+			}
+		},
+	}.Check(t)
+}

cmd/tailscaled/tailscaled.go

@@ -33,8 +33,8 @@ import (
 	"tailscale.com/client/local"
 	"tailscale.com/cmd/tailscaled/childproc"
 	"tailscale.com/control/controlclient"
-	"tailscale.com/drive/driveimpl"
 	"tailscale.com/envknob"
+	"tailscale.com/feature"
 	_ "tailscale.com/feature/condregister"
 	"tailscale.com/hostinfo"
 	"tailscale.com/ipn"
@@ -153,7 +153,6 @@ var subCommands = map[string]*func([]string) error{
 	"uninstall-system-daemon": &uninstallSystemDaemon,
 	"debug":                   &debugModeFunc,
 	"be-child":                &beChildFunc,
-	"serve-taildrive":         &serveDriveFunc,
 }
 
 var beCLI func() // non-nil if CLI is linked in with the "ts_include_cli" build tag
@@ -480,7 +479,9 @@ func run() (err error) {
 		debugMux = newDebugMux()
 	}
 
-	sys.Set(driveimpl.NewFileSystemForRemote(logf))
+	if f, ok := hookSetSysDrive.GetOk(); ok {
+		f(sys, logf)
+	}
 
 	if app := envknob.App(); app != "" {
 		hostinfo.SetApp(app)
@@ -489,6 +490,11 @@ func run() (err error) {
 	return startIPNServer(context.Background(), logf, pol.PublicID, sys)
 }
 
+var (
+	hookSetSysDrive           feature.Hook[func(*tsd.System, logger.Logf)]
+	hookSetWgEnginConfigDrive feature.Hook[func(*wgengine.Config, logger.Logf)]
+)
+
 var sigPipe os.Signal // set by sigpipe.go
 
 func startIPNServer(ctx context.Context, logf logger.Logf, logID logid.PublicID, sys *tsd.System) error {
@@ -749,7 +755,9 @@ func tryEngine(logf logger.Logf, sys *tsd.System, name string) (onlyNetstack boo
 		SetSubsystem:  sys.Set,
 		ControlKnobs:  sys.ControlKnobs(),
 		EventBus:      sys.Bus.Get(),
-		DriveForLocal: driveimpl.NewFileSystemForLocal(logf),
+	}
+	if f, ok := hookSetWgEnginConfigDrive.GetOk(); ok {
+		f(&conf, logf)
 	}
 
 	sys.HealthTracker().SetMetricsRegistry(sys.UserMetricsRegistry())
@@ -943,35 +951,6 @@ func beChild(args []string) error {
 	return f(args[1:])
 }
 
-var serveDriveFunc = serveDrive
-
-// serveDrive serves one or more Taildrives on localhost using the WebDAV
-// protocol. On UNIX and MacOS tailscaled environment, Taildrive spawns child
-// tailscaled processes in serve-taildrive mode in order to access the fliesystem
-// as specific (usually unprivileged) users.
-//
-// serveDrive prints the address on which it's listening to stdout so that the
-// parent process knows where to connect to.
-func serveDrive(args []string) error {
-	if len(args) == 0 {
-		return errors.New("missing shares")
-	}
-	if len(args)%2 != 0 {
-		return errors.New("need <sharename> <path> pairs")
-	}
-	s, err := driveimpl.NewFileServer()
-	if err != nil {
-		return fmt.Errorf("unable to start Taildrive file server: %v", err)
-	}
-	shares := make(map[string]string)
-	for i := 0; i < len(args); i += 2 {
-		shares[args[i]] = args[i+1]
-	}
-	s.SetShares(shares)
-	fmt.Printf("%v\n", s.Addr())
-	return s.Serve()
-}
-
 // dieOnPipeReadErrorOfFD reads from the pipe named by fd and exit the process
 // when the pipe becomes readable. We use this in tests as a somewhat more
 // portable mechanism for the Linux PR_SET_PDEATHSIG, which we wish existed on

cmd/tailscaled/tailscaled_drive.go

@@ -0,0 +1,56 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !ts_omit_drive
+
+package main
+
+import (
+	"errors"
+	"fmt"
+
+	"tailscale.com/drive/driveimpl"
+	"tailscale.com/tsd"
+	"tailscale.com/types/logger"
+	"tailscale.com/wgengine"
+)
+
+func init() {
+	subCommands["serve-taildrive"] = &serveDriveFunc
+
+	hookSetSysDrive.Set(func(sys *tsd.System, logf logger.Logf) {
+		sys.Set(driveimpl.NewFileSystemForRemote(logf))
+	})
+	hookSetWgEnginConfigDrive.Set(func(conf *wgengine.Config, logf logger.Logf) {
+		conf.DriveForLocal = driveimpl.NewFileSystemForLocal(logf)
+	})
+}
+
+var serveDriveFunc = serveDrive
+
+// serveDrive serves one or more Taildrives on localhost using the WebDAV
+// protocol. On UNIX and MacOS tailscaled environment, Taildrive spawns child
+// tailscaled processes in serve-taildrive mode in order to access the fliesystem
+// as specific (usually unprivileged) users.
+//
+// serveDrive prints the address on which it's listening to stdout so that the
+// parent process knows where to connect to.
+func serveDrive(args []string) error {
+	if len(args) == 0 {
+		return errors.New("missing shares")
+	}
+	if len(args)%2 != 0 {
+		return errors.New("need <sharename> <path> pairs")
+	}
+	s, err := driveimpl.NewFileServer()
+	if err != nil {
+		return fmt.Errorf("unable to start Taildrive file server: %v", err)
+	}
+	shares := make(map[string]string)
+	for i := 0; i < len(args); i += 2 {
+		shares[args[i]] = args[i+1]
+	}
+	s.SetShares(shares)
+	fmt.Printf("%v\n", s.Addr())
+	return s.Serve()
+}