func (s *serviceSuite) TestNewServiceKnown(c *gc.C) {
	for _, test := range []struct {
		series     string
		initSystem string
	}{
		{
			series:     "vivid",
			initSystem: service.InitSystemSystemd,
		}, {
			series:     "trusty",
			initSystem: service.InitSystemUpstart,
		}, {
			series:     "win2012",
			initSystem: service.InitSystemWindows,
		},
	} {
		svc, err := service.NewService(s.Name, s.Conf, test.series)
		if !c.Check(err, jc.ErrorIsNil) {
			continue
		}

		switch test.initSystem {
		case service.InitSystemSystemd:
			c.Check(svc, gc.FitsTypeOf, &systemd.Service{})
		case service.InitSystemUpstart:
			c.Check(svc, gc.FitsTypeOf, &upstart.Service{})
		case service.InitSystemWindows:
			c.Check(svc, gc.FitsTypeOf, &windows.Service{})
		}
		c.Check(svc.Name(), gc.Equals, s.Name)
		c.Check(svc.Conf(), jc.DeepEquals, s.Conf)
	}
}

func (a *MachineAgent) uninstallAgent(agentConfig agent.Config) error {
	var errors []error
	agentServiceName := agentConfig.Value(agent.AgentServiceName)
	if agentServiceName == "" {
		// For backwards compatibility, handle lack of AgentServiceName.
		agentServiceName = os.Getenv("UPSTART_JOB")
	}
	if agentServiceName != "" {
		if err := service.NewService(agentServiceName, common.Conf{}).Remove(); err != nil {
			errors = append(errors, fmt.Errorf("cannot remove service %q: %v", agentServiceName, err))
		}
	}
	// Remove the juju-run symlink.
	if err := os.Remove(jujuRun); err != nil && !os.IsNotExist(err) {
		errors = append(errors, err)
	}

	namespace := agentConfig.Value(agent.Namespace)
	if err := mongo.RemoveService(namespace); err != nil {
		errors = append(errors, fmt.Errorf("cannot stop/remove mongo service with namespace %q: %v", namespace, err))
	}
	if err := os.RemoveAll(agentConfig.DataDir()); err != nil {
		errors = append(errors, err)
	}
	if len(errors) == 0 {
		return nil
	}
	return fmt.Errorf("uninstall failed: %v", errors)
}

// findUpstartJob tries to find an upstart job matching the
// given unit name in one of these formats:
//   jujud-<deployer-tag>:<unit-tag>.conf (for compatibility)
//   jujud-<unit-tag>.conf (default)
func (ctx *SimpleContext) findUpstartJob(unitName string) service.Service {
	unitsAndJobs, err := ctx.deployedUnitsUpstartJobs()
	if err != nil {
		return nil
	}
	if job, ok := unitsAndJobs[unitName]; ok {
		svc := service.NewService(job, common.Conf{InitDir: ctx.initDir})
		return svc
	}
	return nil
}

// IsRunningLocally returns true if LXD is running locally.
func IsRunningLocally() (bool, error) {
	installed, err := IsInstalledLocally()
	if err != nil {
		return installed, errors.Trace(err)
	}
	if !installed {
		return false, nil
	}

	svc, err := service.NewService("lxd", common.Conf{}, series.HostSeries())
	if err != nil {
		return false, errors.Trace(err)
	}

	running, err := svc.Running()
	if err != nil {
		return running, errors.Trace(err)
	}

	return running, nil
}

func shutdownInitCommands(initSystem, series string) ([]string, error) {
	shutdownCmd := "/sbin/shutdown -h now"
	name := "juju-template-restart"
	desc := "juju shutdown job"

	execStart := shutdownCmd

	conf := common.Conf{
		Desc:         desc,
		Transient:    true,
		AfterStopped: "cloud-final",
		ExecStart:    execStart,
	}
	// systemd uses targets for synchronization of services
	if initSystem == service.InitSystemSystemd {
		conf.AfterStopped = "cloud-config.target"
	}

	svc, err := service.NewService(name, conf, series)
	if err != nil {
		return nil, errors.Trace(err)
	}

	cmds, err := svc.InstallCommands()
	if err != nil {
		return nil, errors.Trace(err)
	}

	startCommands, err := svc.StartCommands()
	if err != nil {
		return nil, errors.Trace(err)
	}
	cmds = append(cmds, startCommands...)

	return cmds, nil
}

}

func (cfg *InstanceConfig) ToolsDir(renderer shell.Renderer) string {
	return cfg.agentInfo().ToolsDir(renderer)
}

func (cfg *InstanceConfig) InitService(renderer shell.Renderer) (service.Service, error) {
	conf := service.AgentConf(cfg.agentInfo(), renderer)

	name := cfg.MachineAgentServiceName
	svc, err := newService(name, conf, cfg.Series)
	return svc, errors.Trace(err)
}

var newService = func(name string, conf common.Conf, series string) (service.Service, error) {
	return service.NewService(name, conf, series)
}

func (cfg *InstanceConfig) AgentConfig(
	tag names.Tag,
	toolsVersion version.Number,
) (agent.ConfigSetter, error) {
	// TODO for HAState: the stateHostAddrs and apiHostAddrs here assume that
	// if the instance is a controller then to use localhost.  This may be
	// sufficient, but needs thought in the new world order.
	var password string
	if cfg.MongoInfo == nil {
		password = cfg.APIInfo.Password
	} else {
		password = cfg.MongoInfo.Password
	}

func shutdownInitCommands(initSystem, series string) ([]string, error) {
	// These files are removed just before the template shuts down.
	cleanupOnShutdown := []string{
		// We remove any dhclient lease files so there's no chance a
		// clone to reuse a lease from the template it was cloned
		// from.
		"/var/lib/dhcp/dhclient*",
		// Both of these sets of files below are recreated on boot and
		// if we leave them in the template's rootfs boot logs coming
		// from cloned containers will be appended. It's better to
		// keep clean logs for diagnosing issues / debugging.
		"/var/log/cloud-init*.log",
	}

	// Using EOC below as the template shutdown script is itself
	// passed through cat > ... < EOF.
	replaceNetConfCmd := fmt.Sprintf(
		"/bin/cat > /etc/network/interfaces << EOC%sEOC\n  ",
		defaultEtcNetworkInterfaces,
	)
	paths := strings.Join(cleanupOnShutdown, " ")
	removeCmd := fmt.Sprintf("/bin/rm -fr %s\n  ", paths)
	shutdownCmd := "/sbin/shutdown -h now"
	name := "juju-template-restart"
	desc := "juju shutdown job"

	execStart := shutdownCmd
	if environs.AddressAllocationEnabled() {
		// Only do the cleanup and replacement of /e/n/i when address
		// allocation feature flag is enabled.
		execStart = replaceNetConfCmd + removeCmd + shutdownCmd
	}

	conf := common.Conf{
		Desc:         desc,
		Transient:    true,
		AfterStopped: "cloud-final",
		ExecStart:    execStart,
	}
	// systemd uses targets for synchronization of services
	if initSystem == service.InitSystemSystemd {
		conf.AfterStopped = "cloud-config.target"
	}

	svc, err := service.NewService(name, conf, series)
	if err != nil {
		return nil, errors.Trace(err)
	}

	cmds, err := svc.InstallCommands()
	if err != nil {
		return nil, errors.Trace(err)
	}

	startCommands, err := svc.StartCommands()
	if err != nil {
		return nil, errors.Trace(err)
	}
	cmds = append(cmds, startCommands...)

	return cmds, nil
}

// Restore handles either returning or creating a controller to a backed up status:
// * extracts the content of the given backup file and:
// * runs mongorestore with the backed up mongo dump
// * updates and writes configuration files
// * updates existing db entries to make sure they hold no references to
// old instances
// * updates config in all agents.
func (b *backups) Restore(backupId string, dbInfo *DBInfo, args RestoreArgs) (names.Tag, error) {
	meta, backupReader, err := b.Get(backupId)
	if err != nil {
		return nil, errors.Annotatef(err, "could not fetch backup %q", backupId)
	}

	defer backupReader.Close()

	workspace, err := NewArchiveWorkspaceReader(backupReader)
	if err != nil {
		return nil, errors.Annotate(err, "cannot unpack backup file")
	}
	defer workspace.Close()

	// This might actually work, but we don't have a guarantee so we don't allow it.
	if meta.Origin.Series != args.NewInstSeries {
		return nil, errors.Errorf("cannot restore a backup made in a machine with series %q into a machine with series %q, %#v", meta.Origin.Series, args.NewInstSeries, meta)
	}

	// TODO(perrito666) Create a compatibility table of sorts.
	vers := meta.Origin.Version
	if vers.Major != 2 {
		return nil, errors.Errorf("Juju version %v cannot restore backups made using Juju version %v", version.Current.Minor, vers)
	}
	backupMachine := names.NewMachineTag(meta.Origin.Machine)

	// The path for the config file might change if the tag changed
	// and also the rest of the path, so we assume as little as possible.
	oldDatadir, err := paths.DataDir(args.NewInstSeries)
	if err != nil {
		return nil, errors.Annotate(err, "cannot determine DataDir for the restored machine")
	}

	var oldAgentConfig agent.ConfigSetterWriter
	oldAgentConfigFile := agent.ConfigPath(oldDatadir, args.NewInstTag)
	if oldAgentConfig, err = agent.ReadConfig(oldAgentConfigFile); err != nil {
		return nil, errors.Annotate(err, "cannot load old agent config from disk")
	}

	logger.Infof("stopping juju-db")
	if err = mongo.StopService(); err != nil {
		return nil, errors.Annotate(err, "failed to stop mongo")
	}

	// delete all the files to be replaced
	if err := PrepareMachineForRestore(oldAgentConfig.MongoVersion()); err != nil {
		return nil, errors.Annotate(err, "cannot delete existing files")
	}
	logger.Infof("deleted old files to place new")

	if err := workspace.UnpackFilesBundle(filesystemRoot()); err != nil {
		return nil, errors.Annotate(err, "cannot obtain system files from backup")
	}
	logger.Infof("placed new restore files")

	var agentConfig agent.ConfigSetterWriter
	// The path for the config file might change if the tag changed
	// and also the rest of the path, so we assume as little as possible.
	datadir, err := paths.DataDir(args.NewInstSeries)
	if err != nil {
		return nil, errors.Annotate(err, "cannot determine DataDir for the restored machine")
	}
	agentConfigFile := agent.ConfigPath(datadir, backupMachine)
	if agentConfig, err = agent.ReadConfig(agentConfigFile); err != nil {
		return nil, errors.Annotate(err, "cannot load agent config from disk")
	}
	ssi, ok := agentConfig.StateServingInfo()
	if !ok {
		return nil, errors.Errorf("cannot determine state serving info")
	}
	APIHostPorts := network.NewHostPorts(ssi.APIPort, args.PrivateAddress, args.PublicAddress)
	agentConfig.SetAPIHostPorts([][]network.HostPort{APIHostPorts})
	if err := agentConfig.Write(); err != nil {
		return nil, errors.Annotate(err, "cannot write new agent configuration")
	}
	logger.Infof("wrote new agent config for restore")

	if backupMachine.Id() != "0" {
		logger.Infof("extra work needed backup belongs to %q machine", backupMachine.String())
		serviceName := "jujud-" + agentConfig.Tag().String()
		aInfo := service.NewMachineAgentInfo(
			agentConfig.Tag().Id(),
			dataDir,
			paths.MustSucceed(paths.LogDir(args.NewInstSeries)),
		)

		// TODO(perrito666) renderer should have a RendererForSeries, for the moment
		// restore only works on linuxes.
		renderer, _ := shell.NewRenderer("bash")
		serviceAgentConf := service.AgentConf(aInfo, renderer)
		svc, err := service.NewService(serviceName, serviceAgentConf, args.NewInstSeries)
		if err != nil {
			return nil, errors.Annotate(err, "cannot generate service for the restored agent.")
//.........这里部分代码省略.........

// Restore handles either returning or creating a controller to a backed up status:
// * extracts the content of the given backup file and:
// * runs mongorestore with the backed up mongo dump
// * updates and writes configuration files
// * updates existing db entries to make sure they hold no references to
// old instances
// * updates config in all agents.
func (b *backups) Restore(backupId string, args RestoreArgs) (names.Tag, error) {
	meta, backupReader, err := b.Get(backupId)
	if err != nil {
		return nil, errors.Annotatef(err, "could not fetch backup %q", backupId)
	}

	defer backupReader.Close()

	workspace, err := NewArchiveWorkspaceReader(backupReader)
	if err != nil {
		return nil, errors.Annotate(err, "cannot unpack backup file")
	}
	defer workspace.Close()

	// TODO(perrito666) Create a compatibility table of sorts.
	version := meta.Origin.Version
	backupMachine := names.NewMachineTag(meta.Origin.Machine)

	if err := mongo.StopService(); err != nil {
		return nil, errors.Annotate(err, "cannot stop mongo to replace files")
	}

	// delete all the files to be replaced
	if err := PrepareMachineForRestore(); err != nil {
		return nil, errors.Annotate(err, "cannot delete existing files")
	}
	logger.Infof("deleted old files to place new")

	if err := workspace.UnpackFilesBundle(filesystemRoot()); err != nil {
		return nil, errors.Annotate(err, "cannot obtain system files from backup")
	}
	logger.Infof("placed new files")

	var agentConfig agent.ConfigSetterWriter
	// The path for the config file might change if the tag changed
	// and also the rest of the path, so we assume as little as possible.
	datadir, err := paths.DataDir(args.NewInstSeries)
	if err != nil {
		return nil, errors.Annotate(err, "cannot determine DataDir for the restored machine")
	}
	agentConfigFile := agent.ConfigPath(datadir, backupMachine)
	if agentConfig, err = agent.ReadConfig(agentConfigFile); err != nil {
		return nil, errors.Annotate(err, "cannot load agent config from disk")
	}
	ssi, ok := agentConfig.StateServingInfo()
	if !ok {
		return nil, errors.Errorf("cannot determine state serving info")
	}
	APIHostPorts := network.NewHostPorts(ssi.APIPort, args.PrivateAddress)
	agentConfig.SetAPIHostPorts([][]network.HostPort{APIHostPorts})
	if err := agentConfig.Write(); err != nil {
		return nil, errors.Annotate(err, "cannot write new agent configuration")
	}
	logger.Infof("wrote new agent config")

	if backupMachine.Id() != "0" {
		logger.Infof("extra work needed backup belongs to %q machine", backupMachine.String())
		serviceName := "jujud-" + agentConfig.Tag().String()
		aInfo := service.NewMachineAgentInfo(
			agentConfig.Tag().Id(),
			dataDir,
			paths.MustSucceed(paths.LogDir(args.NewInstSeries)),
		)

		// TODO(perrito666) renderer should have a RendererForSeries, for the moment
		// restore only works on linuxes.
		renderer, _ := shell.NewRenderer("bash")
		serviceAgentConf := service.AgentConf(aInfo, renderer)
		svc, err := service.NewService(serviceName, serviceAgentConf, args.NewInstSeries)
		if err != nil {
			return nil, errors.Annotate(err, "cannot generate service for the restored agent.")
		}
		if err := svc.Install(); err != nil {
			return nil, errors.Annotate(err, "cannot install service for the restored agent.")
		}
		logger.Infof("new machine service")
	}

	logger.Infof("mongo service will be reinstalled to ensure its presence")
	if err := ensureMongoService(agentConfig); err != nil {
		return nil, errors.Annotate(err, "failed to reinstall service for juju-db")
	}

	logger.Infof("new mongo will be restored")
	// Restore mongodb from backup
	if err := placeNewMongoService(workspace.DBDumpDir, version); err != nil {
		return nil, errors.Annotate(err, "error restoring state from backup")
	}

	// Re-start replicaset with the new value for server address
	dialInfo, err := newDialInfo(args.PrivateAddress, agentConfig)
	if err != nil {
		return nil, errors.Annotate(err, "cannot produce dial information")
//.........这里部分代码省略.........

func (s *serviceSuite) TestNewServiceUnknown(c *gc.C) {
	_, err := service.NewService(s.Name, s.Conf, "<unknown>")

	c.Check(err, jc.Satisfies, errors.IsNotFound)
}

func (s *serviceSuite) TestNewServiceMissingName(c *gc.C) {
	_, err := service.NewService("", s.Conf, service.InitSystemUpstart)

	c.Check(err, gc.ErrorMatches, `.*missing name.*`)
}

// service returns a service.Service corresponding to the specified
// unit.
func (ctx *SimpleContext) service(unitName string) service.Service {
	tag := names.NewUnitTag(unitName).String()
	svcName := "jujud-" + tag
	svc := service.NewService(svcName, common.Conf{InitDir: ctx.initDir})
	return svc
}