runc/1807.patch

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From ecf53c23545092019602578583031c28fde4d2a1 Mon Sep 17 00:00:00 2001
From: Giuseppe Scrivano <gscrivan@redhat.com>
Date: Fri, 25 May 2018 18:04:06 +0200
Subject: [PATCH] sd-notify: do not hang when NOTIFY_SOCKET is used with create
if NOTIFY_SOCKET is used, do not block the main runc process waiting
for events on the notify socket. Change the logic to create a new
process that monitors exclusively the notify socket until an event is
received.
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
---
init.go | 12 +++++++
notify_socket.go | 101 ++++++++++++++++++++++++++++++++++++++++++++++---------
signals.go | 5 +--
3 files changed, 99 insertions(+), 19 deletions(-)
diff --git a/init.go b/init.go
index c8f453192..6a3d9e91c 100644
--- a/init.go
+++ b/init.go
@@ -20,6 +20,18 @@ var initCommand = cli.Command{
Name: "init",
Usage: `initialize the namespaces and launch the process (do not call it outside of runc)`,
Action: func(context *cli.Context) error {
+ // If NOTIFY_SOCKET is used create a new process that stays around
+ // so to not block "runc start". It will automatically exits when the
+ // container notifies that it is ready, or when the container is deleted
+ if os.Getenv("_NOTIFY_SOCKET_FD") != "" {
+ fd := os.Getenv("_NOTIFY_SOCKET_FD")
+ pid := os.Getenv("_NOTIFY_SOCKET_PID")
+ hostNotifySocket := os.Getenv("_NOTIFY_SOCKET_HOST")
+ notifySocketPath := os.Getenv("_NOTIFY_SOCKET_PATH")
+ notifySocketInit(fd, pid, hostNotifySocket, notifySocketPath)
+ os.Exit(0)
+ }
+
factory, _ := libcontainer.New("")
if err := factory.StartInitialization(); err != nil {
// as the error is sent back to the parent there is no need to log
diff --git a/notify_socket.go b/notify_socket.go
index cd6c0a989..e04e9d660 100644
--- a/notify_socket.go
+++ b/notify_socket.go
@@ -6,10 +6,13 @@ import (
"bytes"
"fmt"
"net"
+ "os"
+ "os/exec"
"path/filepath"
+ "strconv"
+ "time"
"github.com/opencontainers/runtime-spec/specs-go"
-
"github.com/sirupsen/logrus"
"github.com/urfave/cli"
)
@@ -64,24 +67,94 @@ func (s *notifySocket) setupSocket() error {
return nil
}
+func (notifySocket *notifySocket) notifyNewPid(pid int) {
+ notifySocketHostAddr := net.UnixAddr{Name: notifySocket.host, Net: "unixgram"}
+ client, err := net.DialUnix("unixgram", nil, &notifySocketHostAddr)
+ if err != nil {
+ return
+ }
+ newPid := fmt.Sprintf("MAINPID=%d\n", pid)
+ client.Write([]byte(newPid))
+}
+
// pid1 must be set only with -d, as it is used to set the new process as the main process
// for the service in systemd
func (notifySocket *notifySocket) run(pid1 int) {
- buf := make([]byte, 512)
- notifySocketHostAddr := net.UnixAddr{Name: notifySocket.host, Net: "unixgram"}
- client, err := net.DialUnix("unixgram", nil, &notifySocketHostAddr)
+ file, err := notifySocket.socket.File()
if err != nil {
logrus.Error(err)
return
}
- for {
- r, err := notifySocket.socket.Read(buf)
- if err != nil {
- break
+ defer file.Close()
+ defer notifySocket.socket.Close()
+
+ cmd := exec.Command("/proc/self/exe", "init")
+ cmd.ExtraFiles = []*os.File{file}
+ cmd.Env = append(cmd.Env, "_NOTIFY_SOCKET_FD=3",
+ fmt.Sprintf("_NOTIFY_SOCKET_PID=%d", pid1),
+ fmt.Sprintf("_NOTIFY_SOCKET_HOST=%s", notifySocket.host),
+ fmt.Sprintf("_NOTIFY_SOCKET_PATH=%s", notifySocket.socketPath))
+
+ if err := cmd.Start(); err != nil {
+ logrus.Fatal(err)
+ }
+ notifySocket.notifyNewPid(cmd.Process.Pid)
+ cmd.Process.Release()
+}
+
+func notifySocketInit(envFd string, envPid string, notifySocketHost string, notifySocketPath string) {
+ intFd, err := strconv.Atoi(envFd)
+ if err != nil {
+ return
+ }
+ pid1, err := strconv.Atoi(envPid)
+ if err != nil {
+ return
+ }
+
+ file := os.NewFile(uintptr(intFd), "unixgram")
+ defer file.Close()
+
+ fileChan := make(chan []byte)
+ exitChan := make(chan bool)
+
+ go func() {
+ for {
+ buf := make([]byte, 512)
+ r, err := file.Read(buf)
+ if err != nil {
+ return
+ }
+ fileChan <- buf[0:r]
}
- var out bytes.Buffer
- for _, line := range bytes.Split(buf[0:r], []byte{'\n'}) {
- if bytes.HasPrefix(line, []byte("READY=")) {
+ }()
+ go func() {
+ for {
+ if _, err := os.Stat(notifySocketPath); os.IsNotExist(err) {
+ exitChan <- true
+ return
+ }
+ time.Sleep(time.Second)
+ }
+ }()
+
+ notifySocketHostAddr := net.UnixAddr{Name: notifySocketHost, Net: "unixgram"}
+ client, err := net.DialUnix("unixgram", nil, &notifySocketHostAddr)
+ if err != nil {
+ return
+ }
+
+ for {
+ select {
+ case <-exitChan:
+ return
+ case b := <-fileChan:
+ for _, line := range bytes.Split(b, []byte{'\n'}) {
+ if !bytes.HasPrefix(line, []byte("READY=")) {
+ continue
+ }
+
+ var out bytes.Buffer
_, err = out.Write(line)
if err != nil {
return
@@ -98,10 +171,8 @@ func (notifySocket *notifySocket) run(pid1 int) {
}
// now we can inform systemd to use pid1 as the pid to monitor
- if pid1 > 0 {
- newPid := fmt.Sprintf("MAINPID=%d\n", pid1)
- client.Write([]byte(newPid))
- }
+ newPid := fmt.Sprintf("MAINPID=%d\n", pid1)
+ client.Write([]byte(newPid))
return
}
}
diff --git a/signals.go b/signals.go
index 1811de837..d0988cb39 100644
--- a/signals.go
+++ b/signals.go
@@ -70,7 +70,7 @@ func (h *signalHandler) forward(process *libcontainer.Process, tty *tty, detach
h.notifySocket.run(pid1)
return 0, nil
} else {
- go h.notifySocket.run(0)
+ h.notifySocket.run(os.Getpid())
}
}
@@ -98,9 +98,6 @@ func (h *signalHandler) forward(process *libcontainer.Process, tty *tty, detach
// status because we must ensure that any of the go specific process
// fun such as flushing pipes are complete before we return.
process.Wait()
- if h.notifySocket != nil {
- h.notifySocket.Close()
- }
return e.status, nil
}
}