This commit is contained in:
Rudi 2022-07-25 14:55:20 -04:00
parent 0c30219945
commit 3ce25c19e4
Signed by: rudi
GPG Key ID: EF64F3CBD1A1EBDD
3 changed files with 109 additions and 0 deletions

3
go.mod Normal file
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module git.sdf.org/rudi/headless9
go 1.18

BIN
headless9 Executable file

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106
main.go Normal file
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package main
import (
"bufio"
"fmt"
"log"
"os"
"os/exec"
"time"
)
var (
controlFile = "/adm/services"
services = make(map[string]string)
)
func main() {
log.Println("Starting headless9")
for {
log.Printf("Refreshing controlFile %+v", controlFile)
startup, err := readLines(controlFile)
if err != nil {
log.Fatalln(err)
}
for _, svc := range startup {
running := false
for runningProc := range services {
if svc == runningProc {
running = true
log.Printf("%+v exists as PID %+v", svc, services[svc])
}
}
if !running {
log.Printf("Svc not detected, starting: %+v", svc)
go execCommand(svc)
}
}
err = watchFile(controlFile)
if err != nil {
log.Println(err)
}
}
}
func execCommand(cmd string, arg ...string) {
proc := exec.Command(cmd, arg...)
// open the out file for writing
outfile, err := os.Create(fmt.Sprintf("/adm/log/%+v.log", cmd))
if err != nil {
panic(err)
}
infile, err := os.Create(fmt.Sprintf("/adm/log/%+v.ctl", cmd))
if err != nil {
panic(err)
}
defer outfile.Close()
defer infile.Close()
proc.Stderr = outfile
proc.Stdout = outfile
proc.Stdin = infile
err = proc.Start()
if err != nil {
panic(err)
}
services[cmd] = fmt.Sprint(proc.Process.Pid)
proc.Wait()
}
// readLines reads a whole file into memory
// and returns a slice of its lines.
func readLines(path string) ([]string, error) {
file, err := os.Open(path)
if err != nil {
return nil, err
}
defer file.Close()
var lines []string
scanner := bufio.NewScanner(file)
for scanner.Scan() {
lines = append(lines, scanner.Text())
}
return lines, scanner.Err()
}
func watchFile(filePath string) error {
initialStat, err := os.Stat(filePath)
if err != nil {
return err
}
for {
stat, err := os.Stat(filePath)
if err != nil {
return err
}
if stat.Size() != initialStat.Size() || stat.ModTime() != initialStat.ModTime() {
break
}
time.Sleep(250 * time.Millisecond)
}
return nil
}