[teleport-update] Add support for systemd process management

lib/autoupdate/agent/config.go

@@ -0,0 +1,122 @@
+/*
+ * Teleport
+ * Copyright (C) 2024  Gravitational, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package agent
+
+import (
+	"context"
+	"errors"
+	"log/slog"
+	"os"
+	"path/filepath"
+	"text/template"
+
+	"github.com/google/renameio/v2"
+	"github.com/gravitational/trace"
+)
+
+const (
+	updateServiceTemplate = `# teleport-update
+[Unit]
+Description=Teleport auto-update service
+
+[Service]
+Type=oneshot
+ExecStart={{.LinkDir}}/bin/teleport-update update
+`
+	updateTimerTemplate = `# teleport-update
+[Unit]
+Description=Teleport auto-update timer unit
+
+[Timer]
+OnActiveSec=1m
+OnUnitActiveSec=5m
+RandomizedDelaySec=1m
+
+[Install]
+WantedBy=teleport.service
+`
+)
+
+func Setup(ctx context.Context, log *slog.Logger, linkDir, dataDir string) error {
+	err := writeConfigFiles(linkDir, dataDir)
+	if err != nil {
+		return trace.Errorf("failed to write teleport-update systemd config files: %w", err)
+	}
+	svc := &SystemdService{
+		ServiceName: "teleport-update.timer",
+		Log:         log,
+	}
+	err = svc.Sync(ctx)
+	if errors.Is(err, ErrNotSupported) {
+		log.WarnContext(ctx, "Not enabling systemd service because systemd is not running.")
+		return nil
+	}
+	if err != nil {
+		return trace.Errorf("failed to sync systemd config: %w", err)
+	}
+	if err := svc.Enable(ctx, true); err != nil {
+		return trace.Errorf("failed to enable teleport-update systemd timer: %w", err)
+	}
+	return nil
+}
+
+func writeConfigFiles(linkDir, dataDir string) error {
+	// TODO(sclevine): revert on failure
+
+	servicePath := filepath.Join(linkDir, serviceDir, updateServiceName)
+	err := writeTemplate(servicePath, updateServiceTemplate, linkDir, dataDir)
+	if err != nil {
+		return trace.Wrap(err)
+	}
+	timerPath := filepath.Join(linkDir, serviceDir, updateTimerName)
+	err = writeTemplate(timerPath, updateTimerTemplate, linkDir, dataDir)
+	if err != nil {
+		return trace.Wrap(err)
+	}
+
+	return nil
+}
+
+func writeTemplate(path, t, linkDir, dataDir string) error {
+	if err := os.MkdirAll(filepath.Dir(path), systemDirMode); err != nil {
+		return trace.Wrap(err)
+	}
+	opts := []renameio.Option{
+		renameio.WithPermissions(configFileMode),
+		renameio.WithExistingPermissions(),
+	}
+	f, err := renameio.NewPendingFile(path, opts...)
+	if err != nil {
+		return trace.Wrap(err)
+	}
+	defer f.Cleanup()
+
+	tmpl, err := template.New(filepath.Base(path)).Parse(t)
+	if err != nil {
+		return trace.Wrap(err)
+	}
+	err = tmpl.Execute(f, struct {
+		LinkDir string
+		DataDir string
+	}{linkDir, dataDir})
+	if err != nil {
+		return trace.Wrap(err)
+	}
+	return trace.Wrap(f.CloseAtomicallyReplace())
+}

lib/autoupdate/agent/config_test.go

@@ -0,0 +1,65 @@
+/*
+ * Teleport
+ * Copyright (C) 2024  Gravitational, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package agent
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	libdefaults "github.com/gravitational/teleport/lib/defaults"
+	"github.com/gravitational/teleport/lib/utils/golden"
+)
+
+func TestWriteConfigFiles(t *testing.T) {
+	t.Parallel()
+	linkDir := t.TempDir()
+	dataDir := t.TempDir()
+	err := writeConfigFiles(linkDir, dataDir)
+	require.NoError(t, err)
+
+	for _, p := range []string{
+		filepath.Join(linkDir, serviceDir, updateServiceName),
+		filepath.Join(linkDir, serviceDir, updateTimerName),
+	} {
+		t.Run(filepath.Base(p), func(t *testing.T) {
+			data, err := os.ReadFile(p)
+			require.NoError(t, err)
+			data = replaceValues(data, map[string]string{
+				DefaultLinkDir:      linkDir,
+				libdefaults.DataDir: dataDir,
+			})
+			if golden.ShouldSet() {
+				golden.Set(t, data)
+			}
+			require.Equal(t, string(golden.Get(t)), string(data))
+		})
+	}
+}
+
+func replaceValues(data []byte, m map[string]string) []byte {
+	for k, v := range m {
+		data = bytes.ReplaceAll(data, []byte(v),
+			[]byte(k))
+	}
+	return data
+}

lib/autoupdate/agent/installer.go

@@ -55,11 +55,15 @@ const (
 	systemDirMode = 0755
 )
 
-var (
+const (
 	// serviceDir contains the relative path to the Teleport SystemD service dir.
-	serviceDir = filepath.Join("lib", "systemd", "system")
+	serviceDir = "lib/systemd/system"
 	// serviceName contains the name of the Teleport SystemD service file.
 	serviceName = "teleport.service"
+	// updateServiceName contains the name of the Teleport Update Systemd service
+	updateServiceName = "teleport-update.service"
+	// updateTimerName contains the name of the Teleport Update Systemd timer
+	updateTimerName = "teleport-update.timer"
 )
 
 // LocalInstaller manages the creation and removal of installations
@@ -539,7 +543,7 @@ func (li *LocalInstaller) forceLinks(ctx context.Context, binDir, svcDir string)
 	dst := filepath.Join(li.LinkServiceDir, serviceName)
 	orig, err := forceCopy(dst, src, maxServiceFileSize)
 	if err != nil && !errors.Is(err, os.ErrExist) {
-		return revert, trace.Errorf("failed to create file for %s: %w", serviceName, err)
+		return revert, trace.Errorf("failed to write file %s: %w", serviceName, err)
 	}
 	if orig != nil {
 		revertFiles = append(revertFiles, *orig)
@@ -782,13 +786,5 @@ func (li *LocalInstaller) isLinked(versionDir string) (bool, error) {
 			return true, nil
 		}
 	}
-	linkData, err := readFileN(filepath.Join(li.LinkServiceDir, serviceName), maxServiceFileSize)
-	if err != nil {
-		return false, nil
-	}
-	versionData, err := readFileN(filepath.Join(versionDir, serviceDir, serviceName), maxServiceFileSize)
-	if err != nil {
-		return false, nil
-	}
-	return bytes.Equal(linkData, versionData), nil
+	return false, nil
 }