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parser.go
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parser.go
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package immortal
import (
"bufio"
"flag"
"fmt"
"io/ioutil"
"os"
"os/user"
"path/filepath"
"sort"
"strings"
"gopkg.in/yaml.v3"
"github.com/immortal/natcasesort"
)
// Parser interface
type Parser interface {
Parse(fs *flag.FlagSet) (*Flags, error)
parseYml(file string) (*Config, error)
checkWrkdir(dir string) error
parseEnvdir(dir string) (map[string]string, error)
checkUser(username string) (*user.User, error)
}
// Parse implements parser
type Parse struct {
Flags
UserLookup func(username string) (*user.User, error)
}
// Parse parse the command line flags
func (p *Parse) Parse(fs *flag.FlagSet) (*Flags, error) {
fs.BoolVar(&p.Flags.Nodaemon, "n", false, "No daemon mode, stay in the foreground")
fs.BoolVar(&p.Flags.Version, "v", false, "Print version")
fs.IntVar(&p.Flags.Retries, "r", -1, "`number` of retries before program exit")
fs.BoolVar(&p.Flags.CheckConfig, "cc", false, "Checks the config file")
fs.StringVar(&p.Flags.ChildPid, "p", "", "Path to write the child `pidfile`")
fs.StringVar(&p.Flags.Configfile, "c", "", "`run.yml` configuration file")
fs.StringVar(&p.Flags.Ctl, "ctl", "", "Create supervise directory `/var/run/immortal/<service>`. Overrides `-name`")
fs.StringVar(&p.Flags.Envdir, "e", "", "Set environment variables specified by files in the `dir`")
fs.StringVar(&p.Flags.FollowPid, "f", "", "Follow PID in `pidfile`")
fs.StringVar(&p.Flags.Logfile, "l", "", "Write stdout/stderr to `logfile`")
fs.StringVar(&p.Flags.Logger, "logger", "", "A `command` to pipe stdout/stderr to stdin")
fs.StringVar(&p.Flags.Name, "name", "", "A name for the service. This differs from -ctl in that it affects `${HOME}/.immortal/<name>`.")
fs.StringVar(&p.Flags.ParentPid, "P", "", "Path to write the supervisor `pidfile`")
fs.StringVar(&p.Flags.User, "u", "", "Execute command on behalf `user`")
fs.StringVar(&p.Flags.Wrkdir, "d", "", "Change to `dir` before starting the command")
fs.UintVar(&p.Flags.Wait, "w", 0, "`seconds` to wait before starting")
err := fs.Parse(os.Args[1:])
if err != nil {
return nil, err
}
return &p.Flags, nil
}
func (p *Parse) parseYml(file string) (*Config, error) {
f, err := ioutil.ReadFile(file)
if err != nil {
return nil, err
}
// set defaults
var cfg = Config{Retries: -1}
if err := yaml.Unmarshal(f, &cfg); err != nil {
return nil, fmt.Errorf("unable to parse YAML file %q %s", file, err)
}
return &cfg, nil
}
func (p *Parse) checkWrkdir(dir string) error {
if !isDir(dir) {
return fmt.Errorf("-d %q does not exist or has wrong permissions, use (\"%s -h\") for help", dir, os.Args[0])
}
return nil
}
func (p *Parse) parseEnvdir(dir string) (map[string]string, error) {
if !isDir(dir) {
return nil, fmt.Errorf("-e %q does not exist or has wrong permissions, use (\"%s -h\") for help", dir, os.Args[0])
}
files, err := ioutil.ReadDir(dir)
if err != nil {
return nil, err
}
env := make(map[string]string)
for _, f := range files {
if f.Mode().IsRegular() {
lines := 0
ff, err := os.Open(filepath.Join(dir, f.Name()))
if err != nil {
continue
}
defer ff.Close()
s := bufio.NewScanner(ff)
for s.Scan() {
if lines >= 1 {
break
}
env[f.Name()] = s.Text()
lines++
}
}
}
return env, nil
}
// checkUser needs cgo
func (p *Parse) checkUser(u string) (*user.User, error) {
usr, err := p.UserLookup(u)
if err != nil {
if _, ok := err.(user.UnknownUserError); ok {
return nil, fmt.Errorf("user %q does not exist", u)
}
return nil, fmt.Errorf("error looking up user: %q. %s", u, err)
}
return usr, nil
}
// Usage prints to standard error a usage message
func (p *Parse) Usage(fs *flag.FlagSet) func() {
return func() {
fmt.Fprintf(os.Stderr, "Usage: %s [-v] [-n] [-cc] [-c run.yml] [-ctl dir] [-d dir] [-e dir] [-f pidfile] [-l logfile] [-logger logger] [-p child_pidfile] [-P supervisor_pidfile] [-r retries] [-u user] [-w seconds] command\n\n command\n The command with arguments if any, to supervise\n\n", os.Args[0])
var flags []string
fs.VisitAll(func(f *flag.Flag) {
flags = append(flags, f.Name)
})
sort.Sort(natcasesort.Sort(flags))
for _, v := range flags {
f := fs.Lookup(v)
s := fmt.Sprintf(" -%s", f.Name)
name, usage := flag.UnquoteUsage(f)
if len(name) > 0 {
s += " " + name
}
if len(s) <= 4 {
s += "\t"
} else {
s += "\n \t"
}
s += usage
fmt.Fprintf(os.Stderr, "%s\n", s)
}
}
}
// ParseArgs parse command arguments
func ParseArgs(p Parser, fs *flag.FlagSet) (cfg *Config, err error) {
flags, err := p.Parse(fs)
if err != nil {
return
}
// if -v
if flags.Version {
return
}
// if -ctl, defaults to /var/run/immortal
var sdir string
if flags.Ctl != "" {
if s := filepath.Clean(flags.Ctl); strings.HasPrefix(s, "/") {
sdir = s
} else {
sdir = filepath.Join(GetSdir(), filepath.Base(s))
}
}
// if -cc
if flags.CheckConfig {
if flags.Configfile == "" {
err = fmt.Errorf("missing config file: -c run.yml, use (\"%s -h\") for help", os.Args[0])
}
}
// if -c
if flags.Configfile != "" {
if !isFile(flags.Configfile) {
err = fmt.Errorf("cannot read file: %q, use (\"%s -h\") for help", flags.Configfile, os.Args[0])
return
}
// parse the `run.yml` file
cfg, err = p.parseYml(flags.Configfile)
if err != nil {
return
}
// Save ConfigFile to use service name derived from file name instead of the PID
cfg.configFile = flags.Configfile
// Cmd is mandatory, is the command that needs to be supervised
if cfg.Cmd == "" {
err = fmt.Errorf("missing command, use (\"%s -h\") for help", os.Args[0])
return
}
// split command into a slice of strings
cfg.command = strings.Fields(cfg.Cmd)
// Change working directory, will: cd Cwd before starting
if cfg.Cwd != "" {
if err = p.checkWrkdir(cfg.Cwd); err != nil {
return
}
}
// The user to run the process on behalf
if cfg.User != "" {
if cfg.user, err = p.checkUser(cfg.User); err != nil {
return
}
}
cfg.ctl = sdir
// print config and exit 0 if config ok
if flags.CheckConfig {
y, _ := yaml.Marshal(&cfg)
fmt.Printf("%s", y)
return nil, nil
}
return
}
// if no args
if len(fs.Args()) < 1 {
err = fmt.Errorf("missing command, use (\"%s -h\") for help", os.Args[0])
return
}
// create new cfg if not using run.yml
cfg = new(Config)
cfg.Log.Size = 1
cfg.Retries = -1
cfg.cli = true
cfg.command = fs.Args()
cfg.ctl = sdir
if flags.Name != "" {
cfg.name = flags.Name
}
// if -d
if flags.Wrkdir != "" {
if err = p.checkWrkdir(flags.Wrkdir); err != nil {
return
}
cfg.Cwd = flags.Wrkdir
}
// if -e
if flags.Envdir != "" {
if cfg.Env, err = p.parseEnvdir(flags.Envdir); err != nil {
return
}
}
// if -f
if flags.FollowPid != "" {
cfg.Pid.Follow = flags.FollowPid
}
// if -l
if flags.Logfile != "" {
cfg.Log.File = flags.Logfile
}
// if -logger
if flags.Logger != "" {
cfg.Logger = flags.Logger
}
// if -P
if flags.ParentPid != "" {
cfg.Pid.Parent = flags.ParentPid
}
// if -p
if flags.ChildPid != "" {
cfg.Pid.Child = flags.ChildPid
}
// if -r
if flags.Retries >= 0 {
cfg.Retries = flags.Retries
}
// if -w
if flags.Wait > 0 {
cfg.Wait = flags.Wait
}
// if -u
if flags.User != "" {
if cfg.user, err = p.checkUser(flags.User); err != nil {
return
}
}
return
}