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tailscale/util/systemd/systemd_linux.go

80 lines
2.0 KiB
Go

// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build linux
// +build linux
package systemd
import (
"errors"
"log"
"os"
"sync"
"github.com/mdlayher/sdnotify"
)
var getNotifyOnce struct {
sync.Once
v *sdnotify.Notifier
}
type logOnce struct {
sync.Once
}
func (l *logOnce) logf(format string, args ...any) {
l.Once.Do(func() {
log.Printf(format, args...)
})
}
var (
readyOnce = &logOnce{}
statusOnce = &logOnce{}
)
func notifier() *sdnotify.Notifier {
getNotifyOnce.Do(func() {
var err error
getNotifyOnce.v, err = sdnotify.New()
// Not exist means probably not running under systemd, so don't log.
if err != nil && !errors.Is(err, os.ErrNotExist) {
log.Printf("systemd: systemd-notifier error: %v", err)
}
})
return getNotifyOnce.v
}
// Ready signals readiness to systemd. This will unblock service dependents from starting.
func Ready() {
err := notifier().Notify(sdnotify.Ready)
if err != nil {
readyOnce.logf("systemd: error notifying: %v", err)
}
}
// Status sends a single line status update to systemd so that information shows up
// in systemctl output. For example:
//
// $ systemctl status tailscale
// ● tailscale.service - Tailscale client daemon
// Loaded: loaded (/nix/store/qc312qcy907wz80fqrgbbm8a9djafmlg-unit-tailscale.service/tailscale.service; enabled; vendor preset: enabled)
// Active: active (running) since Tue 2020-11-24 17:54:07 EST; 13h ago
// Main PID: 26741 (.tailscaled-wra)
// Status: "Connected; user@host.domain.tld; 100.101.102.103"
// IP: 0B in, 0B out
// Tasks: 22 (limit: 4915)
// Memory: 30.9M
// CPU: 2min 38.469s
// CGroup: /system.slice/tailscale.service
// └─26741 /nix/store/sv6cj4mw2jajm9xkbwj07k29dj30lh0n-tailscale-date.20200727/bin/tailscaled --port 41641
func Status(format string, args ...any) {
err := notifier().Notify(sdnotify.Statusf(format, args...))
if err != nil {
statusOnce.logf("systemd: error notifying: %v", err)
}
}