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108 lines
3.7 KiB
Go
108 lines
3.7 KiB
Go
package signal
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import (
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"os"
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gosignal "os/signal"
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"path/filepath"
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"runtime"
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"sync/atomic"
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"syscall"
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"time"
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"github.com/Sirupsen/logrus"
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)
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// Trap sets up a simplified signal "trap", appropriate for common
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// behavior expected from a vanilla unix command-line tool in general
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// (and the Docker engine in particular).
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//
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// * If SIGINT or SIGTERM are received, `cleanup` is called, then the process is terminated.
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// * If SIGINT or SIGTERM are received 3 times before cleanup is complete, then cleanup is
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// skipped and the process is terminated immediately (allows force quit of stuck daemon)
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// * A SIGQUIT always causes an exit without cleanup, with a goroutine dump preceding exit.
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// * Ignore SIGPIPE events. These are generated by systemd when journald is restarted while
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// the docker daemon is not restarted and also running under systemd.
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// Fixes https://github.com/docker/docker/issues/19728
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//
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func Trap(cleanup func()) {
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c := make(chan os.Signal, 1)
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// we will handle INT, TERM, QUIT, SIGPIPE here
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signals := []os.Signal{os.Interrupt, syscall.SIGTERM, syscall.SIGQUIT, syscall.SIGPIPE}
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gosignal.Notify(c, signals...)
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go func() {
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interruptCount := uint32(0)
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for sig := range c {
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if sig == syscall.SIGPIPE {
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continue
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}
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go func(sig os.Signal) {
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logrus.Infof("Processing signal '%v'", sig)
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switch sig {
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case os.Interrupt, syscall.SIGTERM:
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if atomic.LoadUint32(&interruptCount) < 3 {
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// Initiate the cleanup only once
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if atomic.AddUint32(&interruptCount, 1) == 1 {
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// Call the provided cleanup handler
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cleanup()
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os.Exit(0)
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} else {
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return
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}
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} else {
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// 3 SIGTERM/INT signals received; force exit without cleanup
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logrus.Info("Forcing docker daemon shutdown without cleanup; 3 interrupts received")
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}
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case syscall.SIGQUIT:
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DumpStacks("")
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logrus.Info("Forcing docker daemon shutdown without cleanup on SIGQUIT")
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}
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//for the SIGINT/TERM, and SIGQUIT non-clean shutdown case, exit with 128 + signal #
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os.Exit(128 + int(sig.(syscall.Signal)))
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}(sig)
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}
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}()
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}
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// DumpStacks dumps the runtime stack.
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func DumpStacks(root string) {
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var (
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buf []byte
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stackSize int
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)
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bufferLen := 16384
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for stackSize == len(buf) {
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buf = make([]byte, bufferLen)
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stackSize = runtime.Stack(buf, true)
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bufferLen *= 2
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}
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buf = buf[:stackSize]
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// Note that if the daemon is started with a less-verbose log-level than "info" (the default), the goroutine
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// traces won't show up in the log.
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if root == "" {
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logrus.Infof("=== BEGIN goroutine stack dump ===\n%s\n=== END goroutine stack dump ===", buf)
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} else {
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// Dumps the stacks to a file in the root directory of the daemon
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// On Windows, this overcomes two issues - one being that if the stack is too big, it doesn't
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// get written to the event log when the Windows daemon is running as a service.
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// Second, using logrus, the tabs and new-lines end up getting written as literal
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// \t and \n's, meaning you need to use something like notepad++ to convert the
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// output into something readable using 'type' from a command line or notepad/notepad++ etc.
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path := filepath.Join(root, "goroutine-stacks.log")
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f, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0666)
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if err != nil {
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logrus.Warnf("Could not open %s to write the goroutine stacks: %v", path, err)
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return
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}
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defer f.Close()
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f.WriteString("=== BEGIN goroutine stack dump ===\n")
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f.WriteString(time.Now().String() + "\n")
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if _, err := f.Write(buf); err != nil {
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logrus.Warnf("Could not write goroutine stacks to %s: %v", path, err)
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return
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}
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f.WriteString("=== END goroutine stack dump ===\n")
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f.Sync()
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logrus.Infof("goroutine stacks written to %s", path)
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}
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}
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