From cd9b959b34c183cf6cd031af678c4ec66b765080 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano 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. Bind mount the parent directory of the notify socket, so that "start" can create the socket and it is still accessible from the container. Signed-off-by: Giuseppe Scrivano --- notify_socket.go | 113 ++++++++++++++++++++++++++++++++++------------- signals.go | 5 +-- start.go | 13 +++++- utils_linux.go | 12 ++++- 4 files changed, 106 insertions(+), 37 deletions(-) diff --git a/notify_socket.go b/notify_socket.go index cd6c0a98..7fbd2e73 100644 --- a/notify_socket.go +++ b/notify_socket.go @@ -6,11 +6,14 @@ import ( "bytes" "fmt" "net" + "os" + "path" "path/filepath" + "strconv" + "time" + "github.com/opencontainers/runc/libcontainer" "github.com/opencontainers/runtime-spec/specs-go" - - "github.com/sirupsen/logrus" "github.com/urfave/cli" ) @@ -26,12 +29,12 @@ func newNotifySocket(context *cli.Context, notifySocketHost string, id string) * } root := filepath.Join(context.GlobalString("root"), id) - path := filepath.Join(root, "notify.sock") + socketPath := filepath.Join(root, "notify", "notify.sock") notifySocket := ¬ifySocket{ socket: nil, host: notifySocketHost, - socketPath: path, + socketPath: socketPath, } return notifySocket @@ -43,13 +46,19 @@ func (ns *notifySocket) Close() error { // If systemd is supporting sd_notify protocol, this function will add support // for sd_notify protocol from within the container. -func (s *notifySocket) setupSpec(context *cli.Context, spec *specs.Spec) { - mount := specs.Mount{Destination: s.host, Source: s.socketPath, Options: []string{"bind"}} +func (s *notifySocket) setupSpec(context *cli.Context, spec *specs.Spec) error { + pathInContainer := filepath.Join("/run/notify", path.Base(s.socketPath)) + mount := specs.Mount{ + Destination: path.Dir(pathInContainer), + Source: path.Dir(s.socketPath), + Options: []string{"bind", "nosuid", "noexec", "nodev", "ro"}, + } spec.Mounts = append(spec.Mounts, mount) - spec.Process.Env = append(spec.Process.Env, fmt.Sprintf("NOTIFY_SOCKET=%s", s.host)) + spec.Process.Env = append(spec.Process.Env, fmt.Sprintf("NOTIFY_SOCKET=%s", pathInContainer)) + return nil } -func (s *notifySocket) setupSocket() error { +func (s *notifySocket) bindSocket() error { addr := net.UnixAddr{ Name: s.socketPath, Net: "unixgram", @@ -64,45 +73,89 @@ func (s *notifySocket) setupSocket() error { return nil } -// 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"} +func (s *notifySocket) setupSocketDirectory() error { + return os.Mkdir(path.Dir(s.socketPath), 0755) +} + +func notifySocketStart(context *cli.Context, notifySocketHost, id string) (*notifySocket, error) { + notifySocket := newNotifySocket(context, notifySocketHost, id) + if notifySocket == nil { + return nil, nil + } + + if err := notifySocket.bindSocket(); err != nil { + return nil, err + } + return notifySocket, nil +} + +func (n *notifySocket) waitForContainer(container libcontainer.Container) error { + s, err := container.State() + if err != nil { + return err + } + return n.run(s.InitProcessPid) +} + +func (n *notifySocket) run(pid1 int) error { + if n.socket == nil { + return nil + } + notifySocketHostAddr := net.UnixAddr{Name: n.host, Net: "unixgram"} client, err := net.DialUnix("unixgram", nil, ¬ifySocketHostAddr) if err != nil { - logrus.Error(err) - return + return err } - for { - r, err := notifySocket.socket.Read(buf) - if err != nil { - break + + ticker := time.NewTicker(time.Millisecond * 100) + defer ticker.Stop() + + fileChan := make(chan []byte) + go func() { + for { + buf := make([]byte, 512) + r, err := n.socket.Read(buf) + if err != nil { + return + } + got := buf[0:r] + if !bytes.HasPrefix(got, []byte("READY=")) { + continue + } + fileChan <- got + return } - var out bytes.Buffer - for _, line := range bytes.Split(buf[0:r], []byte{'\n'}) { - if bytes.HasPrefix(line, []byte("READY=")) { + }() + + for { + select { + case <-ticker.C: + _, err := os.Stat(filepath.Join("/proc", strconv.Itoa(pid1))) + if err != nil { + return nil + } + case b := <-fileChan: + for _, line := range bytes.Split(b, []byte{'\n'}) { + var out bytes.Buffer _, err = out.Write(line) if err != nil { - return + return err } _, err = out.Write([]byte{'\n'}) if err != nil { - return + return err } _, err = client.Write(out.Bytes()) if err != nil { - return + return err } // 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)) - } - return + newPid := fmt.Sprintf("MAINPID=%d\n", pid1) + client.Write([]byte(newPid)) + return nil } } } diff --git a/signals.go b/signals.go index 1811de83..d0988cb3 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 } } diff --git a/start.go b/start.go index 2bb698b2..3a1769a4 100644 --- a/start.go +++ b/start.go @@ -3,6 +3,7 @@ package main import ( "errors" "fmt" + "os" "github.com/opencontainers/runc/libcontainer" "github.com/urfave/cli" @@ -31,7 +32,17 @@ your host.`, } switch status { case libcontainer.Created: - return container.Exec() + notifySocket, err := notifySocketStart(context, os.Getenv("NOTIFY_SOCKET"), container.ID()) + if err != nil { + return err + } + if err := container.Exec(); err != nil { + return err + } + if notifySocket != nil { + return notifySocket.waitForContainer(container) + } + return nil case libcontainer.Stopped: return errors.New("cannot start a container that has stopped") case libcontainer.Running: diff --git a/utils_linux.go b/utils_linux.go index c6a34897..77423f67 100644 --- a/utils_linux.go +++ b/utils_linux.go @@ -420,7 +420,9 @@ func startContainer(context *cli.Context, spec *specs.Spec, action CtAct, criuOp notifySocket := newNotifySocket(context, os.Getenv("NOTIFY_SOCKET"), id) if notifySocket != nil { - notifySocket.setupSpec(context, spec) + if err := notifySocket.setupSpec(context, spec); err != nil { + return -1, err + } } container, err := createContainer(context, id, spec) @@ -429,10 +431,16 @@ func startContainer(context *cli.Context, spec *specs.Spec, action CtAct, criuOp } if notifySocket != nil { - err := notifySocket.setupSocket() + err := notifySocket.setupSocketDirectory() if err != nil { return -1, err } + if action == CT_ACT_RUN { + err := notifySocket.bindSocket() + if err != nil { + return -1, err + } + } } // Support on-demand socket activation by passing file descriptors into the container init process. -- 2.17.1