diff --git a/conmon/conmon.c b/conmon/conmon.c index 126a7dbd..02210b0f 100644 --- a/conmon/conmon.c +++ b/conmon/conmon.c @@ -76,6 +76,9 @@ int main(int argc, char *argv[]) struct termios t; struct epoll_event ev; struct epoll_event evlist[MAX_EVENTS]; + int child_pipe = -1; + char *sync_pipe, *endptr; + int len; while ((opt = getopt(argc, argv, "tc:")) != -1) { switch(opt) { @@ -101,6 +104,14 @@ int main(int argc, char *argv[]) nexit("Container ID not passed"); } + sync_pipe = getenv("_OCI_SYNCPIPE"); + if (sync_pipe) { + errno = 0; + child_pipe = strtol(sync_pipe, &endptr, 10); + if (errno != 0 || *endptr != '\0') + pexit("unable to parse _OCI_SYNCPIPE"); + } + /* * Set self as subreaper so we can wait for container process * and return its exit code. @@ -155,6 +166,14 @@ int main(int argc, char *argv[]) cpid = atoi(contents); printf("container PID: %d\n", cpid); + /* Send the container pid back to parent */ + if (child_pipe > 0) { + len = snprintf(buf, BUF_SIZE, "{\"pid\": %d}\n", cpid); + if (len < 0 || write(child_pipe, buf, len) != len) { + pexit("unable to send container pid to parent"); + } + } + if (terminal) { /* Save exiting termios settings */ if (tcgetattr(STDIN_FILENO, &tty_orig) == -1) diff --git a/oci/oci.go b/oci/oci.go index c4bad957..476a61a6 100644 --- a/oci/oci.go +++ b/oci/oci.go @@ -9,8 +9,10 @@ import ( "path/filepath" "strings" "sync" + "syscall" "time" + "github.com/Sirupsen/logrus" "github.com/kubernetes-incubator/ocid/utils" "github.com/opencontainers/runtime-spec/specs-go" ) @@ -32,6 +34,11 @@ type Runtime struct { containerDir string } +// syncInfo is used to return data from monitor process to daemon +type syncInfo struct { + Pid int `"json:pid"` +} + // Name returns the name of the OCI Runtime func (r *Runtime) Name() string { return r.name @@ -69,7 +76,46 @@ func getOCIVersion(name string, args ...string) (string, error) { // CreateContainer creates a container. func (r *Runtime) CreateContainer(c *Container) error { - return utils.ExecCmdWithStdStreams(os.Stdin, os.Stdout, os.Stderr, r.path, "--systemd-cgroup", "create", "--bundle", c.bundlePath, c.name) + parentPipe, childPipe, err := newPipe() + if err != nil { + return fmt.Errorf("error creating socket pair: %v", err) + } + defer parentPipe.Close() + + args := []string{"-c", c.name} + if c.terminal { + args = append(args, "-t") + } + + cmd := exec.Command("conmon", args...) + cmd.Dir = c.bundlePath + cmd.SysProcAttr = &syscall.SysProcAttr{ + Setpgid: true, + } + cmd.Stdin = os.Stdin + cmd.Stdout = os.Stdout + cmd.Stderr = os.Stderr + cmd.ExtraFiles = append(cmd.ExtraFiles, childPipe) + // 0, 1 and 2 are stdin, stdout and stderr + cmd.Env = append(cmd.Env, fmt.Sprintf("_OCI_SYNCPIPE=%d", 3)) + + err = cmd.Start() + if err != nil { + childPipe.Close() + return err + } + + // We don't need childPipe on the parent side + childPipe.Close() + + // Wait to get container pid from conmon + // TODO(mrunalp): Add a timeout here + var si *syncInfo + if err := json.NewDecoder(parentPipe).Decode(&si); err != nil { + return fmt.Errorf("reading pid from init pipe: %v", err) + } + logrus.Infof("Received container pid: %v", si.Pid) + return nil } // StartContainer starts a container. @@ -178,3 +224,12 @@ func (c *Container) NetNsPath() (string, error) { } return fmt.Sprintf("/proc/%d/ns/net", c.state.Pid), nil } + +// newPipe creates a unix socket pair for communication +func newPipe() (parent *os.File, child *os.File, err error) { + fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM|syscall.SOCK_CLOEXEC, 0) + if err != nil { + return nil, nil, err + } + return os.NewFile(uintptr(fds[1]), "parent"), os.NewFile(uintptr(fds[0]), "child"), nil +}