go-systemd example

go.mod

module example.com

replace github.com/coreos/go-systemd => github.com/coreos/go-systemd/v22 v22.0.0

go 1.13

require github.com/coreos/go-systemd v0.0.0-00010101000000-000000000000 // indirect

main.go

package main

import (
	"fmt"
	"log"
	"time"

	"github.com/coreos/go-systemd/dbus"
	"github.com/coreos/go-systemd/journal"
)

const unitName = "nginx.service"

func main() {
	conn, err := dbus.NewSystemConnection()
	if err != nil {
		log.Fatal(err.Error())
	}
	defer conn.Close()

	// list unit's properties
	properties, err := conn.GetUnitProperties(unitName)
	if err != nil {
		log.Fatal(err.Error())
	}
	for k, v := range properties {
		fmt.Printf("%s: %v\n", k, v)
	}

	// send log
	journal.Send("send to journald", journal.PriInfo, map[string]string{"SYSLOG_IDENTIFIER": "go-systemd"})
	journal.Print(journal.PriInfo, "go-systemd: hello") // go-systemd will not show as SYSLOG_IDENTIFIER

	statusChan, errChan := conn.SubscribeUnits(time.Second)

	// it will list all units first
	select {
	case m := <-statusChan:
		for k, v := range m {
			fmt.Printf("event: %v: %v\n", k, *v)
		}
	case err := <-errChan:
		fmt.Printf("error: %v\n", err.Error())
	}

	stop := make(chan struct{}, 0)

	go func() {
		time.Sleep(1 * time.Second)
		fmt.Printf("disable [%s]\n", unitName)
		conn.DisableUnitFiles([]string{unitName}, false)

		time.Sleep(1 * time.Second)
		fmt.Printf("enable [%s]\n", unitName)
		conn.EnableUnitFiles([]string{unitName}, false, true)

		time.Sleep(1 * time.Second)
		resultChan := make(chan string)
		// second args: replace, fail, isolate, ignore-dependencies, ignore-requirements
		// result can be nil, possible value: done, canceled, timeout, failed, dependency, skipped.
		jobID, err := conn.StopUnit(unitName, "replace", resultChan)
		if err == nil {
			fmt.Printf("stop [%s]: job ID=%d\n", unitName, jobID)
			s := <-resultChan
			fmt.Printf("stop result: %v\n", s)
		} else {
			fmt.Printf("failed to stop [%s]: %s\n", unitName, err.Error())
		}

		time.Sleep(1 * time.Second)
		jobID, err = conn.StartUnit(unitName, "replace", resultChan)
		if err == nil {
			fmt.Printf("start [%s]: job ID=%d\n", unitName, jobID)
			s := <-resultChan
			fmt.Printf("start result: %v\n", s)
		} else {
			fmt.Printf("failed to start [%s]: %s\n", unitName, err.Error())
		}

		time.Sleep(1 * time.Second)
		stop <- struct{}{}
	}()

	// wait done
Loop:
	for {
		select {
		case m := <-statusChan:
			for k, v := range m {
				fmt.Printf("event: %v: %v\n", k, *v)
			}
		case err := <-errChan:
			fmt.Printf("error: %v\n", err.Error())
			break Loop
		case <-stop:
			break Loop
		}
	}
}