clientupdate: exec systemctl instead of using dbus to restart (#11923)

Shell out to "systemctl", which lets us drop an extra dependency.

Updates https://github.com/tailscale/corp/issues/18935

Signed-off-by: Andrew Lytvynov <[email protected]>

clientupdate/clientupdate.go

@@ -1019,6 +1019,20 @@ func (up *Updater) updateLinuxBinary() error {
 	return nil
 }
 
+func restartSystemdUnit(ctx context.Context) error {
+	if _, err := exec.LookPath("systemctl"); err != nil {
+		// Likely not a systemd-managed distro.
+		return errors.ErrUnsupported
+	}
+	if out, err := exec.Command("systemctl", "daemon-reload").CombinedOutput(); err != nil {
+		return fmt.Errorf("systemctl daemon-reload failed: %w\noutput: %s", err, out)
+	}
+	if out, err := exec.Command("systemctl", "restart", "tailscaled.service").CombinedOutput(); err != nil {
+		return fmt.Errorf("systemctl restart failed: %w\noutput: %s", err, out)
+	}
+	return nil
+}
+
 func (up *Updater) downloadLinuxTarball(ver string) (string, error) {
 	dlDir, err := os.UserCacheDir()
 	if err != nil {

clientupdate/systemd_linux.go

@@ -1,37 +0,0 @@
-// Copyright (c) Tailscale Inc & AUTHORS
-// SPDX-License-Identifier: BSD-3-Clause
-
-package clientupdate
-
-import (
-	"context"
-	"errors"
-	"fmt"
-
-	"github.com/coreos/go-systemd/v22/dbus"
-)
-
-func restartSystemdUnit(ctx context.Context) error {
-	c, err := dbus.NewWithContext(ctx)
-	if err != nil {
-		// Likely not a systemd-managed distro.
-		return errors.ErrUnsupported
-	}
-	defer c.Close()
-	if err := c.ReloadContext(ctx); err != nil {
-		return fmt.Errorf("failed to reload tailscaled.service: %w", err)
-	}
-	ch := make(chan string, 1)
-	if _, err := c.RestartUnitContext(ctx, "tailscaled.service", "replace", ch); err != nil {
-		return fmt.Errorf("failed to restart tailscaled.service: %w", err)
-	}
-	select {
-	case res := <-ch:
-		if res != "done" {
-			return fmt.Errorf("systemd service restart failed with result %q", res)
-		}
-	case <-ctx.Done():
-		return ctx.Err()
-	}
-	return nil
-}

clientupdate/systemd_other.go

@@ -1,15 +0,0 @@
-// Copyright (c) Tailscale Inc & AUTHORS
-// SPDX-License-Identifier: BSD-3-Clause
-
-//go:build !linux
-
-package clientupdate
-
-import (
-	"context"
-	"errors"
-)
-
-func restartSystemdUnit(ctx context.Context) error {
-	return errors.ErrUnsupported
-}

cmd/tailscale/depaware.txt

@@ -6,11 +6,9 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
    W    github.com/alexbrainman/sspi/internal/common                 from github.com/alexbrainman/sspi/negotiate
    W 💣 github.com/alexbrainman/sspi/negotiate                       from tailscale.com/net/tshttpproxy
    L    github.com/coreos/go-iptables/iptables                       from tailscale.com/util/linuxfw
-   L    github.com/coreos/go-systemd/v22/dbus                        from tailscale.com/clientupdate
    W 💣 github.com/dblohm7/wingoes                                   from github.com/dblohm7/wingoes/pe+
    W 💣 github.com/dblohm7/wingoes/pe                                from tailscale.com/util/winutil/authenticode
         github.com/fxamacker/cbor/v2                                 from tailscale.com/tka
-   L 💣 github.com/godbus/dbus/v5                                    from github.com/coreos/go-systemd/v22/dbus
         github.com/golang/groupcache/lru                             from tailscale.com/net/dnscache
    L    github.com/google/nftables                                   from tailscale.com/util/linuxfw
    L 💣 github.com/google/nftables/alignedbuff                       from github.com/google/nftables/xt
@@ -271,7 +269,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         image/png                                                    from github.com/skip2/go-qrcode
         io                                                           from archive/tar+
         io/fs                                                        from archive/tar+
-        io/ioutil                                                    from github.com/godbus/dbus/v5+
+        io/ioutil                                                    from github.com/mitchellh/go-ps+
         log                                                          from expvar+
         log/internal                                                 from log
         maps                                                         from tailscale.com/clientupdate+

cmd/tailscaled/depaware.txt

@@ -80,7 +80,6 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
    L    github.com/aws/smithy-go/waiter                              from github.com/aws/aws-sdk-go-v2/service/ssm
         github.com/bits-and-blooms/bitset                            from github.com/gaissmai/bart
    L    github.com/coreos/go-iptables/iptables                       from tailscale.com/util/linuxfw
-   L    github.com/coreos/go-systemd/v22/dbus                        from tailscale.com/clientupdate
   LD 💣 github.com/creack/pty                                        from tailscale.com/ssh/tailssh
    W 💣 github.com/dblohm7/wingoes                                   from github.com/dblohm7/wingoes/com+
    W 💣 github.com/dblohm7/wingoes/com                               from tailscale.com/cmd/tailscaled+
@@ -98,7 +97,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         github.com/go-json-experiment/json/jsontext                  from tailscale.com/logtail
    W 💣 github.com/go-ole/go-ole                                     from github.com/go-ole/go-ole/oleutil+
    W 💣 github.com/go-ole/go-ole/oleutil                             from tailscale.com/wgengine/winnet
-   L 💣 github.com/godbus/dbus/v5                                    from github.com/coreos/go-systemd/v22/dbus+
+   L 💣 github.com/godbus/dbus/v5                                    from tailscale.com/net/dns+
         github.com/golang/groupcache/lru                             from tailscale.com/net/dnscache
         github.com/google/btree                                      from gvisor.dev/gvisor/pkg/tcpip/header+
    L    github.com/google/nftables                                   from tailscale.com/util/linuxfw

go.mod

@@ -16,7 +16,6 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/ssm v1.44.7
 	github.com/coreos/go-iptables v0.7.1-0.20240112124308-65c67c9f46e6
 	github.com/coreos/go-systemd v0.0.0-20191104093116-d3cd4ed1dbcf
-	github.com/coreos/go-systemd/v22 v22.5.0
 	github.com/creack/pty v1.1.21
 	github.com/dave/courtney v0.4.0
 	github.com/dave/jennifer v1.7.0

go.sum

@@ -217,8 +217,6 @@ github.com/coreos/go-iptables v0.7.1-0.20240112124308-65c67c9f46e6 h1:8h5+bWd7R6
 github.com/coreos/go-iptables v0.7.1-0.20240112124308-65c67c9f46e6/go.mod h1:Qe8Bv2Xik5FyTXwgIbLAnv2sWSBmvWdFETJConOQ//Q=
 github.com/coreos/go-systemd v0.0.0-20191104093116-d3cd4ed1dbcf h1:iW4rZ826su+pqaw19uhpSCzhj44qo35pNgKFGqzDKkU=
 github.com/coreos/go-systemd v0.0.0-20191104093116-d3cd4ed1dbcf/go.mod h1:F5haX7vjVVG0kc13fIWeqUViNPyEJxv/OmvnBo0Yme4=
-github.com/coreos/go-systemd/v22 v22.5.0 h1:RrqgGjYQKalulkV8NGVIfkXQf6YYmOyiJKk8iXXhfZs=
-github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
 github.com/cpuguy83/go-md2man/v2 v2.0.3/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/creack/pty v1.1.21 h1:1/QdRyBaHHJP61QkWMXlOIBfsgdDeeKfK8SYVUWJKf0=
@@ -362,7 +360,6 @@ github.com/gobuffalo/flect v1.0.2 h1:eqjPGSo2WmjgY2XlpGwo2NXgL3RucAKo4k4qQMNA5sA
 github.com/gobuffalo/flect v1.0.2/go.mod h1:A5msMlrHtLqh9umBSnvabjsMrCcCpAyzglnDvkbYKHs=
 github.com/gobwas/glob v0.2.3 h1:A4xDbljILXROh+kObIiy5kIaPYD8e96x1tgBhUI5J+Y=
 github.com/gobwas/glob v0.2.3/go.mod h1:d3Ez4x06l9bZtSvzIay5+Yzi0fmZzPgnTbPcKjJAkT8=
-github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/godbus/dbus/v5 v5.1.1-0.20230522191255-76236955d466 h1:sQspH8M4niEijh3PFscJRLDnkL547IeP7kpPe3uUhEg=
 github.com/godbus/dbus/v5 v5.1.1-0.20230522191255-76236955d466/go.mod h1:ZiQxhyQ+bbbfxUKVvjfO498oPYvtYhZzycal3G/NHmU=
 github.com/gofrs/flock v0.8.1 h1:+gYjHKf32LDeiEEFhQaotPbLuUXjY5ZqxKgXy7n59aw=