github.com/ssdev-go/moby@v17.12.1-ce-rc2+incompatible/pkg/signal/trap.go (about)

     1  package signal
     2  
     3  import (
     4  	"fmt"
     5  	"os"
     6  	gosignal "os/signal"
     7  	"path/filepath"
     8  	"runtime"
     9  	"strings"
    10  	"sync/atomic"
    11  	"syscall"
    12  	"time"
    13  
    14  	"github.com/pkg/errors"
    15  )
    16  
    17  // Trap sets up a simplified signal "trap", appropriate for common
    18  // behavior expected from a vanilla unix command-line tool in general
    19  // (and the Docker engine in particular).
    20  //
    21  // * If SIGINT or SIGTERM are received, `cleanup` is called, then the process is terminated.
    22  // * If SIGINT or SIGTERM are received 3 times before cleanup is complete, then cleanup is
    23  //   skipped and the process is terminated immediately (allows force quit of stuck daemon)
    24  // * A SIGQUIT always causes an exit without cleanup, with a goroutine dump preceding exit.
    25  // * Ignore SIGPIPE events. These are generated by systemd when journald is restarted while
    26  //   the docker daemon is not restarted and also running under systemd.
    27  //   Fixes https://github.com/docker/docker/issues/19728
    28  //
    29  func Trap(cleanup func(), logger interface {
    30  	Info(args ...interface{})
    31  }) {
    32  	c := make(chan os.Signal, 1)
    33  	// we will handle INT, TERM, QUIT, SIGPIPE here
    34  	signals := []os.Signal{os.Interrupt, syscall.SIGTERM, syscall.SIGQUIT, syscall.SIGPIPE}
    35  	gosignal.Notify(c, signals...)
    36  	go func() {
    37  		interruptCount := uint32(0)
    38  		for sig := range c {
    39  			if sig == syscall.SIGPIPE {
    40  				continue
    41  			}
    42  
    43  			go func(sig os.Signal) {
    44  				logger.Info(fmt.Sprintf("Processing signal '%v'", sig))
    45  				switch sig {
    46  				case os.Interrupt, syscall.SIGTERM:
    47  					if atomic.LoadUint32(&interruptCount) < 3 {
    48  						// Initiate the cleanup only once
    49  						if atomic.AddUint32(&interruptCount, 1) == 1 {
    50  							// Call the provided cleanup handler
    51  							cleanup()
    52  							os.Exit(0)
    53  						} else {
    54  							return
    55  						}
    56  					} else {
    57  						// 3 SIGTERM/INT signals received; force exit without cleanup
    58  						logger.Info("Forcing docker daemon shutdown without cleanup; 3 interrupts received")
    59  					}
    60  				case syscall.SIGQUIT:
    61  					DumpStacks("")
    62  					logger.Info("Forcing docker daemon shutdown without cleanup on SIGQUIT")
    63  				}
    64  				//for the SIGINT/TERM, and SIGQUIT non-clean shutdown case, exit with 128 + signal #
    65  				os.Exit(128 + int(sig.(syscall.Signal)))
    66  			}(sig)
    67  		}
    68  	}()
    69  }
    70  
    71  const stacksLogNameTemplate = "goroutine-stacks-%s.log"
    72  
    73  // DumpStacks appends the runtime stack into file in dir and returns full path
    74  // to that file.
    75  func DumpStacks(dir string) (string, error) {
    76  	var (
    77  		buf       []byte
    78  		stackSize int
    79  	)
    80  	bufferLen := 16384
    81  	for stackSize == len(buf) {
    82  		buf = make([]byte, bufferLen)
    83  		stackSize = runtime.Stack(buf, true)
    84  		bufferLen *= 2
    85  	}
    86  	buf = buf[:stackSize]
    87  	var f *os.File
    88  	if dir != "" {
    89  		path := filepath.Join(dir, fmt.Sprintf(stacksLogNameTemplate, strings.Replace(time.Now().Format(time.RFC3339), ":", "", -1)))
    90  		var err error
    91  		f, err = os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0666)
    92  		if err != nil {
    93  			return "", errors.Wrap(err, "failed to open file to write the goroutine stacks")
    94  		}
    95  		defer f.Close()
    96  		defer f.Sync()
    97  	} else {
    98  		f = os.Stderr
    99  	}
   100  	if _, err := f.Write(buf); err != nil {
   101  		return "", errors.Wrap(err, "failed to write goroutine stacks")
   102  	}
   103  	return f.Name(), nil
   104  }