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httpprocprobed/main.go

153 lines
4.2 KiB
Go

/*
httpprocwatchd provides HTTP interface to a list of process' statuses
formatted as JSON.
Copyright (c) 2021 Alexander "Arav" Andreev <me@arav.top>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package main
import (
"flag"
"fmt"
"log"
"os"
"os/exec"
"os/signal"
"syscall"
)
// listWatchedProcesses prints a list of processes being watched.
func listWatchedProcesses(processes *[]string) {
for _, v := range *processes {
fmt.Printf("%s, ", v)
}
fmt.Println()
}
// version prints information about program.
func version() {
fmt.Println("httpprocwatchd ver. 1.2")
fmt.Println("Copyright (c) 2021 Alexander \"Arav\" Andreev <me@arav.top>")
fmt.Println("License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.")
fmt.Println("This is free software, and you are welcome to change and redistribute it.")
fmt.Println("There is NO WARRANTY, to the extent permitted by law.")
}
func main() {
var oConfigPath string
var oShowVersion bool
var oListProcesses bool
var oAddProcess string
var oRemoveProcess string
log.SetFlags(0)
flag.StringVar(&oConfigPath, "config", "processes.json", "path to configuration file")
flag.StringVar(&oConfigPath, "c", "processes.json", "path to configuration file (shorthand)")
flag.BoolVar(&oShowVersion, "version", false, "show version")
flag.BoolVar(&oShowVersion, "v", false, "show version (shorthand)")
flag.BoolVar(&oListProcesses, "list", false, "list watched processes")
flag.BoolVar(&oListProcesses, "l", false, "list watched processes (shorthand)")
flag.StringVar(&oAddProcess, "add", "", "add process to list")
flag.StringVar(&oAddProcess, "a", "", "add process to list (shorthand)")
flag.StringVar(&oRemoveProcess, "remove", "", "remove process from list")
flag.StringVar(&oRemoveProcess, "r", "", "remove process from list (shorthand)")
flag.Parse()
if oShowVersion {
version()
return
}
if _, err := exec.LookPath("pgrep"); err != nil {
log.Fatalln(ErrPgrepNotFound)
}
conf, err := LoadConfiguration(oConfigPath)
if err != nil {
log.Fatalf("Cannot load configuration file: %s\n", err)
}
if oListProcesses {
listWatchedProcesses(&conf.Processes)
return
}
if oAddProcess != "" {
err := AddProcessToList(oAddProcess, conf, oConfigPath)
if err != nil {
log.Fatalf("Cannot add process: %s\n", err)
}
}
if oRemoveProcess != "" {
err := RemoveProcessFromList(oRemoveProcess, conf, oConfigPath)
if err != nil {
log.Fatalf("Cannot remove process: %s\n", err)
}
}
// If we modified a list then let's look for a running program and
// send SIGHUP for it to reload a list.
if oAddProcess != "" || oRemoveProcess != "" {
isup, pid, _ := IsProcessUp("httpprocwatchd")
if isup && pid != nil && len(pid) > 1 {
var trgt_pid int
if pid[0] == os.Getpid() {
trgt_pid = pid[1]
} else {
trgt_pid = pid[0]
}
proc, err := os.FindProcess(trgt_pid)
if err == nil {
proc.Signal(syscall.SIGHUP)
}
}
return
}
srv := createAndStartHTTPServer(conf)
syssignal := make(chan os.Signal, 1)
signal.Notify(syssignal, os.Interrupt, syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
log.Printf("httpprocwatchd is running on \"%s\".", conf.ListenAddress)
for {
switch <-syssignal {
case os.Interrupt:
fallthrough
case syscall.SIGINT | syscall.SIGTERM:
log.Println("Shutting down... ")
shutdownHTTPServer(srv)
log.Println("Server shutted down.")
os.Exit(0)
case syscall.SIGHUP:
newconf, err := LoadConfiguration(oConfigPath)
if err != nil {
log.Fatalf("Failed to reload configuration: %s\n", err)
}
conf.Processes = newconf.Processes
log.Println("Successfully reloaded a list of watched processes.")
}
}
}