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// Copyright 2012, 2013 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.
package upstart
import (
"bytes"
"errors"
"fmt"
"io/ioutil"
"os"
"os/exec"
"path"
"regexp"
"text/template"
)
var startedRE = regexp.MustCompile(`^.* start/running, process (\d+)\n$`)
// Service provides visibility into and control over an upstart service.
type Service struct {
Name string
InitDir string // defaults to "/etc/init"
}
func NewService(name string) *Service {
return &Service{Name: name, InitDir: "/etc/init"}
}
// confPath returns the path to the service's configuration file.
func (s *Service) confPath() string {
return path.Join(s.InitDir, s.Name+".conf")
}
// Installed returns whether the service configuration exists in the
// init directory.
func (s *Service) Installed() bool {
_, err := os.Stat(s.confPath())
return err == nil
}
// Running returns true if the Service appears to be running.
func (s *Service) Running() bool {
cmd := exec.Command("status", s.Name)
out, err := cmd.CombinedOutput()
if err != nil {
return false
}
return startedRE.Match(out)
}
// Start starts the service.
func (s *Service) Start() error {
if s.Running() {
return nil
}
return runCommand("start", s.Name)
}
func runCommand(args ...string) error {
out, err := exec.Command(args[0], args[1:]...).CombinedOutput()
if err == nil {
return nil
}
out = bytes.TrimSpace(out)
if len(out) > 0 {
return fmt.Errorf("exec %q: %v (%s)", args, err, out)
}
return fmt.Errorf("exec %q: %v", args, err)
}
// Stop stops the service.
func (s *Service) Stop() error {
if !s.Running() {
return nil
}
return runCommand("stop", s.Name)
}
// StopAndRemove stops the service and then deletes the service
// configuration from the init directory.
func (s *Service) StopAndRemove() error {
if !s.Installed() {
return nil
}
if err := s.Stop(); err != nil {
return err
}
return os.Remove(s.confPath())
}
// Remove deletes the service configuration from the init directory.
func (s *Service) Remove() error {
if !s.Installed() {
return nil
}
return os.Remove(s.confPath())
}
// BUG: %q quoting does not necessarily match libnih quoting rules
// (as used by upstart); this may become an issue in the future.
var confT = template.Must(template.New("").Parse(`
description "{{.Desc}}"
author "Juju Team <juju@lists.ubuntu.com>"
start on runlevel [2345]
stop on runlevel [!2345]
respawn
normal exit 0
{{range $k, $v := .Env}}env {{$k}}={{$v|printf "%q"}}
{{end}}
{{range $k, $v := .Limit}}limit {{$k}} {{$v}}
{{end}}
exec {{.Cmd}}{{if .Out}} >> {{.Out}} 2>&1{{end}}
`[1:]))
// Conf is responsible for defining and installing upstart services. Its fields
// represent elements of an upstart service configuration file.
type Conf struct {
Service
// Desc is the upstart service's description.
Desc string
// Env holds the environment variables that will be set when the command runs.
Env map[string]string
// Limit holds the ulimit values that will be set when the command runs.
Limit map[string]string
// Cmd is the command (with arguments) that will be run.
// The command will be restarted if it exits with a non-zero exit code.
Cmd string
// Out, if set, will redirect output to that path.
Out string
}
// validate returns an error if the service is not adequately defined.
func (c *Conf) validate() error {
if c.Name == "" {
return errors.New("missing Name")
}
if c.InitDir == "" {
return errors.New("missing InitDir")
}
if c.Desc == "" {
return errors.New("missing Desc")
}
if c.Cmd == "" {
return errors.New("missing Cmd")
}
return nil
}
// render returns the upstart configuration for the service as a string.
func (c *Conf) render() ([]byte, error) {
if err := c.validate(); err != nil {
return nil, err
}
var buf bytes.Buffer
if err := confT.Execute(&buf, c); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
// Install installs and starts the service.
func (c *Conf) Install() error {
conf, err := c.render()
if err != nil {
return err
}
if c.Installed() {
if err := c.StopAndRemove(); err != nil {
return fmt.Errorf("upstart: could not remove installed service: %s", err)
}
}
if err := ioutil.WriteFile(c.confPath(), conf, 0644); err != nil {
return err
}
return c.Start()
}
// InstallCommands returns shell commands to install and start the service.
func (c *Conf) InstallCommands() ([]string, error) {
conf, err := c.render()
if err != nil {
return nil, err
}
return []string{
fmt.Sprintf("cat >> %s << 'EOF'\n%sEOF\n", c.confPath(), conf),
"start " + c.Name,
}, nil
}
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