// 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) } }