func checkProvisioned(host string) (bool, error) {
	logger.Infof("Checking if %s is already provisioned", host)

	script := service.ListServicesScript()

	cmd := ssh.Command("[email protected]"+host, []string{"/bin/bash"}, nil)
	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr
	cmd.Stdin = strings.NewReader(script)
	if err := cmd.Run(); err != nil {
		if stderr.Len() != 0 {
			err = fmt.Errorf("%v (%v)", err, strings.TrimSpace(stderr.String()))
		}
		return false, err
	}

	output := strings.TrimSpace(stdout.String())
	provisioned := strings.Contains(output, "juju")
	if provisioned {
		logger.Infof("%s is already provisioned [%q]", host, output)
	} else {
		logger.Infof("%s is not provisioned", host)
	}
	return provisioned, nil
}

// Run resolves c.Target to a machine, to the address of a i
// machine or unit forks ssh passing any arguments provided.
func (c *SSHCommand) Run(ctx *cmd.Context) error {
	if c.apiClient == nil {
		// If the apClient is not already opened and it is opened
		// by ensureAPIClient, then close it when we're done.
		defer func() {
			if c.apiClient != nil {
				c.apiClient.Close()
				c.apiClient = nil
			}
		}()
	}
	options, err := c.getSSHOptions(c.pty)
	if err != nil {
		return err
	}

	host, err := c.hostFromTarget(c.Target)
	if err != nil {
		return err
	}
	cmd := ssh.Command("[email protected]"+host, c.Args, options)
	cmd.Stdin = ctx.Stdin
	cmd.Stdout = ctx.Stdout
	cmd.Stderr = ctx.Stderr
	return cmd.Run()
}

func detectSeriesAndHardwareCharacteristics(host string) (hc instance.HardwareCharacteristics, series string, err error) {
	logger.Infof("Detecting series and characteristics on %s", host)
	cmd := ssh.Command("[email protected]"+host, []string{"/bin/bash"}, nil)
	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr
	cmd.Stdin = bytes.NewBufferString(detectionScript)
	if err := cmd.Run(); err != nil {
		if stderr.Len() != 0 {
			err = fmt.Errorf("%v (%v)", err, strings.TrimSpace(stderr.String()))
		}
		return hc, "", err
	}
	lines := strings.Split(stdout.String(), "\n")
	series = strings.TrimSpace(lines[0])

	arch := arch.NormaliseArch(lines[1])
	hc.Arch = &arch

	// HardwareCharacteristics wants memory in megabytes,
	// meminfo reports it in kilobytes.
	memkB := strings.Fields(lines[2])[1] // "MemTotal: NNN kB"
	hc.Mem = new(uint64)
	*hc.Mem, err = strconv.ParseUint(memkB, 10, 0)
	*hc.Mem /= 1024

	// For each "physical id", count the number of cores.
	// This way we only count physical cores, not additional
	// logical cores due to hyperthreading.
	recorded := make(map[string]bool)
	var physicalId string
	hc.CpuCores = new(uint64)
	for _, line := range lines[3:] {
		if strings.HasPrefix(line, "physical id") {
			physicalId = strings.TrimSpace(strings.SplitN(line, ":", 2)[1])
		} else if strings.HasPrefix(line, "cpu cores") {
			var cores uint64
			value := strings.TrimSpace(strings.SplitN(line, ":", 2)[1])
			if cores, err = strconv.ParseUint(value, 10, 0); err != nil {
				return hc, "", err
			}
			if !recorded[physicalId] {
				*hc.CpuCores += cores
				recorded[physicalId] = true
			}
		}
	}
	if *hc.CpuCores == 0 {
		// In the case of a single-core, non-HT CPU, we'll see no
		// "physical id" or "cpu cores" lines.
		*hc.CpuCores = 1
	}

	// TODO(axw) calculate CpuPower. What algorithm do we use?
	logger.Infof("series: %s, characteristics: %s", series, hc)
	return hc, series, nil
}

// RunConfigureScript connects to the specified host over
// SSH, and executes the provided script which is expected
// to have been returned by ConfigureScript.
func RunConfigureScript(script string, params ConfigureParams) error {
	logger.Debugf("Running script on %s: %s", params.Host, script)
	client := params.Client
	if client == nil {
		client = ssh.DefaultClient
	}
	cmd := ssh.Command(params.Host, []string{"sudo", "/bin/bash"}, nil)
	cmd.Stdin = strings.NewReader(script)
	cmd.Stderr = params.ProgressWriter
	return cmd.Run()
}

// InitUbuntuUser adds the ubuntu user if it doesn't
// already exist, updates its ~/.ssh/authorized_keys,
// and enables passwordless sudo for it.
//
// InitUbuntuUser will initially attempt to login as
// the ubuntu user, and verify that passwordless sudo
// is enabled; only if this is false will there be an
// attempt with the specified login.
//
// authorizedKeys may be empty, in which case the file
// will be created and left empty.
//
// stdin and stdout will be used for remote sudo prompts,
// if the ubuntu user must be created/updated.
func InitUbuntuUser(host, login, authorizedKeys string, stdin io.Reader, stdout io.Writer) error {
	logger.Infof("initialising %q, user %q", host, login)

	// To avoid unnecessary prompting for the specified login,
	// initUbuntuUser will first attempt to ssh to the machine
	// as "ubuntu" with password authentication disabled, and
	// ensure that it can use sudo without a password.
	//
	// Note that we explicitly do not allocate a PTY, so we
	// get a failure if sudo prompts.
	cmd := ssh.Command("[email protected]"+host, []string{"sudo", "-n", "true"}, nil)
	if cmd.Run() == nil {
		logger.Infof("ubuntu user is already initialised")
		return nil
	}

	// Failed to login as ubuntu (or passwordless sudo is not enabled).
	// Use specified login, and execute the initUbuntuScript below.
	if login != "" {
		host = login + "@" + host
	}
	script := fmt.Sprintf(initUbuntuScript, utils.ShQuote(authorizedKeys))
	var options ssh.Options
	options.AllowPasswordAuthentication()
	options.EnablePTY()
	cmd = ssh.Command(host, []string{"sudo", "/bin/bash -c " + utils.ShQuote(script)}, &options)
	var stderr bytes.Buffer
	cmd.Stdin = stdin
	cmd.Stdout = stdout // for sudo prompt
	cmd.Stderr = &stderr
	if err := cmd.Run(); err != nil {
		if stderr.Len() != 0 {
			err = fmt.Errorf("%v (%v)", err, strings.TrimSpace(stderr.String()))
		}
		return err
	}
	return nil
}

func runViaSsh(addr string, script string) error {
	// This is taken from cmd/juju/ssh.go there is no other clear way to set user
	userAddr := "[email protected]" + addr
	userCmd := ssh.Command(userAddr, []string{"sudo", "-n", "bash", "-c " + utils.ShQuote(script)}, nil)
	var stderrBuf bytes.Buffer
	var stdoutBuf bytes.Buffer
	userCmd.Stderr = &stderrBuf
	userCmd.Stdout = &stdoutBuf
	err := userCmd.Run()
	if err != nil {
		return errors.Annotate(err, fmt.Sprintf("ssh command failed: (%q)", stderrBuf.String()))
	}
	progress("ssh command succedded: %q", stdoutBuf.String())
	return nil
}

func (r *RestoreSuite) TestRunViaSSH(c *gc.C) {
	var (
		passedAddress string
		passedArgs    []string
	)
	fakeSSHCommand := func(address string, args []string, options *ssh.Options) *ssh.Cmd {
		passedAddress = address
		passedArgs = args
		return ssh.Command("", []string{"ls"}, &ssh.Options{})
	}

	r.PatchValue(&sshCommand, fakeSSHCommand)
	runViaSSH("invalidAddress", "invalidScript")
	c.Assert(passedAddress, gc.Equals, "[email protected]")
	c.Assert(passedArgs, gc.DeepEquals, []string{"sudo", "-n", "bash", "-c 'invalidScript'"})
}

// login uid/gid. This is done so that we don't require sudo, and by
// consequence, don't require a pty, so we can interact with a script
// via stdin.
type SSHStorage struct {
	host       string
	remotepath string
	tmpdir     string

	cmd     *ssh.Cmd
	stdin   io.WriteCloser
	stdout  io.ReadCloser
	scanner *bufio.Scanner
}

var sshCommand = func(host string, command ...string) *ssh.Cmd {
	return ssh.Command(host, command, nil)
}

type flockmode string

const (
	flockShared    flockmode = "-s"
	flockExclusive flockmode = "-x"
)

type NewSSHStorageParams struct {
	// Host is the host to connect to, in the format [[email protected]]hostname.
	Host string

	// StorageDir is the root of the remote storage directory.
	StorageDir string

	logger.Debugf("using ssh storage at host %q dir %q", sshHost, storageDir)
	return sshstorage.NewSSHStorage(sshstorage.NewSSHStorageParams{
		Host:       sshHost,
		StorageDir: storageDir,
		TmpDir:     storageTmpdir,
	})
}

func (e *manualEnviron) Storage() storage.Storage {
	e.cfgmutex.Lock()
	defer e.cfgmutex.Unlock()
	return e.storage
}

var runSSHCommand = func(host string, command []string, stdin string) (stdout string, err error) {
	cmd := ssh.Command(host, command, nil)
	cmd.Stdin = strings.NewReader(stdin)
	var stdoutBuf, stderrBuf bytes.Buffer
	cmd.Stdout = &stdoutBuf
	cmd.Stderr = &stderrBuf
	if err := cmd.Run(); err != nil {
		if stderr := strings.TrimSpace(stderrBuf.String()); len(stderr) > 0 {
			err = errors.Annotate(err, stderr)
		}
		return "", err
	}
	return stdoutBuf.String(), nil
}

func (e *manualEnviron) Destroy() error {
	script := `