/
worker.go
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/
worker.go
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// Diato - Reverse Proxying for Hipsters
//
// Copyright 2016-2017 Dolf Schimmel
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package server
import (
"errors"
"log"
"net"
"os"
"os/exec"
"sync/atomic"
"syscall"
"time"
"diato/util/stop"
)
func (s *Server) startWorkers(workerCount uint) error {
httpFd, err := s.getNewHttpSocket(false)
if err != nil {
return err
}
httpsFd, err := s.getNewHttpSocket(true)
if err != nil {
return err
}
throttle := time.Tick(1 * time.Second)
for i := 1; i <= int(workerCount); i++ {
if err := s.startWorker(i, httpFd, httpsFd, throttle); err != nil {
return err
}
}
return nil
}
func (s *Server) startWorker(id int, httpFd *os.File, httpsFd *os.File, throttle <-chan time.Time) error {
chrootFd, err := s.getChrootFd()
if err != nil {
return err
}
cmd := exec.Command(os.Args[0], "internal-worker", "start")
cmd.ExtraFiles = []*os.File{chrootFd, httpFd, httpsFd}
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.SysProcAttr = &syscall.SysProcAttr{
Setsid: true,
Pdeathsig: syscall.SIGTERM,
}
if err := cmd.Start(); err != nil {
return err
}
atomic.AddInt32(&s.curWorkerCount, 1)
stopper := stop.NewStopper(func() {
cmd.Process.Signal(os.Interrupt)
cmd.Process.Wait()
})
go func() {
cmd.Process.Wait()
remainingWorkerCount := atomic.AddInt32(&s.curWorkerCount, -1)
if stopper.IsStopping() {
return
}
log.Printf("Worker %d died", id)
if remainingWorkerCount < 1 {
log.Println("No workers remaining, that can't be good. Stopping...")
stop.Stop()
return
}
<-throttle
log.Printf("Restarting worker %d...", id)
s.startWorker(id, httpFd, httpsFd, throttle)
}()
return nil
}
// Sets up a new http socket. This socket is used to carry
// plain-text http messages to the worker for further processing
// Messages are supported by the proxy protocol (currently version
// 1) to determine source ip. SSL is stripped in the server daemon.
//
// It is desirable to use version 2 fo the proxy protocol some time
// because it allows to also convey things like SSL usage.
//
// We spawn the socket in the server, the FD is handed over to the
// worker which is responsible for listening and accepting
// connections on this socket. This ensures the worker can run
// in a permission-less environment and does not require any IO.
func (s *Server) getNewHttpSocket(tls bool) (*os.File, error) {
path := s.httpSocketPath
if tls {
path = s.httpsSocketPath
}
listener, err := net.Listen("unix", path)
if err != nil {
return nil, err
}
fd, err := listener.(*net.UnixListener).File()
if err != nil {
return nil, err
}
stop.NewStopper(func() {
os.Remove(path)
})
return fd, nil
}
// Chrooting of the worker is done in plain C where ARGV/ARGC is not
// available. Nor are we going to reimplement the config parser in C,
// as such, we already open and validate the directory that the worker
// should chroot into.
func (s *Server) getChrootFd() (*os.File, error) {
file, err := os.Open(s.chrootPath)
if err != nil {
return nil, err
}
fileinfo, err := file.Stat()
if err != nil {
return nil, err
}
if !fileinfo.IsDir() {
return nil, errors.New("Chroot must be a directory, but it does not appear to be")
}
return file, nil
}