[lxc-devel] [RFC PATCH] allow multiple monitor clients
Dwight Engen
dwight.engen at oracle.com
Thu Apr 18 18:47:01 UTC 2013
On Thu, 18 Apr 2013 14:22:08 -0400
S.Çağlar Onur <caglar at 10ur.org> wrote:
> Hey Dwight,
>
> This sounds great, I'll give it a try ASAP. In the meantime ,if you
> want to test it yourself, you can grab go bindings from github via
> "go get github.com/caglar10ur/lxc" but please keep in your mind that
> you need my other two patches to start/stop work reliably [1]/[2].
> https://github.com/caglar10ur/lxc/tree/master/examples directory
> contains concurrent versions of create/start/stop/shutdown to test.
>
> [1]
> https://github.com/caglar10ur/lxc-upstream/commit/db60b9c38083e8ed553f3cbdd96ad410bd5eb7ed.patch
> [2]
> https://github.com/caglar10ur/lxc-upstream/commit/97d4daf4cc5016bcb01c72e5cf9fe3189e9df4f5.patch
>
> Cheers,
Thanks Caglar, I may give them a try as I've just built go the other
day to try out docker.
> On Thu, Apr 18, 2013 at 2:09 PM, Dwight Engen
> <dwight.engen at oracle.com>wrote:
>
> > After the recent discussions on the lxc monitor, I took a closer
> > look at it. It seems like Serge was resigned to having some sort of
> > daemon as having multicast unix domain supported by the kernel is
> > not going to happen any time soon, and doing it over loopback has
> > some complications too.
> >
> > Initially I thought it would be nice to just have lxc-start "be the
> > daemon" as Stéphane had suggested. I tried this out, putting the fds
> > for the consumer clients (lxc-monitors) in lxc_mainloop , but this
> > is problematic for the scenario where lxc-monitor runs first and we
> > miss some startup states.
> >
> > So here is what I'm proposing: when lxc-monitor starts, it attempts
> > to start lxc-monitord. lxc-monitord creates a fifo and a socket on
> > lxcpath.
> >
> > Producers (containers) wishing to send messages open the fifo and
> > write their lxc_msg's on it. The reason I used a fifo is so that we
> > get permission checks on the opening of it. Right now it is created
> > 0600. This fixes the problem we have today where anyone can open
> > the unix socket and send state changes in.
> >
> > Consumers (lxc-monitor) connect to the unix socket and each gets a
> > copy of the messages. lxc-monitord can do a PEERCRED to ensure the
> > client should be able to get these messages, this is one benefit to
> > using unix domain. I don't think it would be difficult to write a
> > lxc-monitor like client that would bridge the messages onto d-bus.
> >
> > When lxc-monitord hasn't had a client for 30 seconds it will exit.
> >
> > Attached is a proof of concept patch for your comments. It works for
> > the common cases that I've tried but I know it needs some cleanup
> > and testing if we like the approach. The monitor.c part is hard to
> > read because that file is mostly rewritten.
> >
> > I need to test S.Çağlar Onur's scenario of parallel startup with his
> > test script. We need to decide if we want to monitor per lxcpath or
> > per container, today it is per path and I think that being able to
> > do lxc-monitor * would be very useful.
> >
> > --
> >
> > Signed-off-by: Dwight Engen <dwight.engen at oracle.com>
> > ---
> > src/lxc/Makefile.am | 2 +
> > src/lxc/af_unix.c | 5 +-
> > src/lxc/lxc_monitor.c | 2 +
> > src/lxc/lxc_monitord.c | 334
> > +++++++++++++++++++++++++++++++++++++++++++++++++
> > src/lxc/mainloop.c | 11 +-
> > src/lxc/mainloop.h | 7 ++
> > src/lxc/monitor.c | 180 ++++++++++++++++----------
> > src/lxc/monitor.h | 11 +-
> > src/lxc/start.c | 7 +-
> > 9 files changed, 484 insertions(+), 75 deletions(-)
> > create mode 100644 src/lxc/lxc_monitord.c
> >
> > diff --git a/src/lxc/Makefile.am b/src/lxc/Makefile.am
> > index ebeca466..1fa0fa8 100644
> > --- a/src/lxc/Makefile.am
> > +++ b/src/lxc/Makefile.am
> > @@ -150,6 +150,7 @@ bin_PROGRAMS = \
> > lxc-start \
> > lxc-execute \
> > lxc-monitor \
> > + lxc-monitord \
> > lxc-wait \
> > lxc-console \
> > lxc-freeze \
> > @@ -181,6 +182,7 @@ lxc_freeze_SOURCES = lxc_freeze.c
> > lxc_info_SOURCES = lxc_info.c
> > lxc_init_SOURCES = lxc_init.c
> > lxc_monitor_SOURCES = lxc_monitor.c
> > +lxc_monitord_SOURCES = lxc_monitord.c
> > lxc_restart_SOURCES = lxc_restart.c
> > lxc_start_SOURCES = lxc_start.c
> > lxc_stop_SOURCES = lxc_stop.c
> > diff --git a/src/lxc/af_unix.c b/src/lxc/af_unix.c
> > index eff13d4..ceef340 100644
> > --- a/src/lxc/af_unix.c
> > +++ b/src/lxc/af_unix.c
> > @@ -52,6 +52,7 @@ int lxc_af_unix_open(const char *path, int type,
> > int flags)
> >
> > addr.sun_family = AF_UNIX;
> > /* copy entire buffer in case of abstract socket */
> > + /* FIXME: this is unsafe if path is too long... */
> > memcpy(addr.sun_path, path,
> > path[0]?strlen(path):sizeof(addr.sun_path));
> >
> > @@ -61,7 +62,7 @@ int lxc_af_unix_open(const char *path, int type,
> > int flags)
> > errno = tmp;
> > return -1;
> > }
> > -
> > +
> > if (type == SOCK_STREAM && listen(fd, 100)) {
> > int tmp = errno;
> > close(fd);
> > @@ -76,7 +77,7 @@ int lxc_af_unix_close(int fd)
> > {
> > struct sockaddr_un addr;
> > socklen_t addrlen = sizeof(addr);
> > -
> > +
> > if (!getsockname(fd, (struct sockaddr *)&addr, &addrlen) &&
> > addr.sun_path[0])
> > unlink(addr.sun_path);
> > diff --git a/src/lxc/lxc_monitor.c b/src/lxc/lxc_monitor.c
> > index 8c15869..0ca829f 100644
> > --- a/src/lxc/lxc_monitor.c
> > +++ b/src/lxc/lxc_monitor.c
> > @@ -87,6 +87,8 @@ int main(int argc, char *argv[])
> > return -1;
> > }
> >
> > + lxc_monitord_spawn(my_args.lxcpath);
> > +
> > fd = lxc_monitor_open(my_args.lxcpath);
> > if (fd < 0)
> > return -1;
> > diff --git a/src/lxc/lxc_monitord.c b/src/lxc/lxc_monitord.c
> > new file mode 100644
> > index 0000000..3e9c708
> > --- /dev/null
> > +++ b/src/lxc/lxc_monitord.c
> > @@ -0,0 +1,334 @@
> > +/*
> > + * lxc: linux Container library
> > + *
> > + * Copyright © 2012 Oracle.
> > + *
> > + * Authors:
> > + * Dwight Engen <dwight.engen at oracle.com>
> > + *
> > + * This library is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU Lesser General Public
> > + * License as published by the Free Software Foundation; either
> > + * version 2.1 of the License, or (at your option) any later
> > version.
> > + *
> > + * This library is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > GNU
> > + * Lesser General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU Lesser General Public
> > + * License along with this library; if not, write to the Free
> > Software
> > + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
> > 02111-1307 USA
> > + */
> > +
> > +#define _GNU_SOURCE
> > +#include <stdio.h>
> > +#include <signal.h>
> > +#include <errno.h>
> > +#include <unistd.h>
> > +#include <string.h>
> > +#include <stdlib.h>
> > +#include <fcntl.h>
> > +#include <sys/types.h>
> > +#include <sys/stat.h>
> > +#include <sys/param.h>
> > +#include <sys/socket.h>
> > +#include <sys/un.h>
> > +#include <netinet/in.h>
> > +#include <net/if.h>
> > +
> > +#include <lxc/af_unix.h>
> > +#include <lxc/log.h>
> > +#include <lxc/mainloop.h>
> > +#include <lxc/monitor.h>
> > +#include <lxc/utils.h>
> > +
> > +lxc_log_define(lxc_monitord, lxc);
> > +
> > +/*
> > + * Defines the structure to store the monitor information
> > + * @fifofd : the file descriptor for publishers (containers)
> > to write state
> > + * @listenfd : the file descriptor for subscribers
> > (lxc-monitors) to connect
> > + * @clientfds : accepted client file descriptors
> > + * @clientfds_cnt: the count of valid fds in clientfds
> > + */
> > +struct lxc_monitor {
> > + int fifofd;
> > + int listenfd;
> > + int clientfds[1024];
> > + int clientfds_cnt;
> > + struct lxc_epoll_descr descr;
> > +};
> > +
> > +static int lxc_monitord_fifo_create(struct lxc_monitor *mon, const
> > char *lxcpath)
> > +{
> > + char fifo_path[PATH_MAX];
> > + int ret;
> > +
> > + ret = snprintf(fifo_path, sizeof(fifo_path), "%s/monitor",
> > lxcpath);
> > + if (ret < 0 || ret >= sizeof(fifo_path)) {
> > + ERROR("lxcpath too long to monitor fifo");
> > + return -1;
> > + }
> > +
> > + ret = mknod(fifo_path, S_IFIFO|S_IRUSR|S_IWUSR, 0);
> > + if (ret < 0) {
> > + INFO("existing monitor fifo at %s, monitor already
> > running?", fifo_path);
> > + return -1;
> > + }
> > + mon->fifofd = open(fifo_path, O_RDWR);
> > + if (mon->fifofd < 0) {
> > + ERROR("failed to open monitor fifo");
> > + return -1;
> > + }
> > + return 0;
> > +}
> > +
> > +static int lxc_monitord_fifo_delete(const char *lxcpath)
> > +{
> > + char fifo_path[PATH_MAX];
> > + int ret;
> > +
> > + ret = snprintf(fifo_path, sizeof(fifo_path), "%s/monitor",
> > lxcpath);
> > + if (ret < 0 || ret >= sizeof(fifo_path)) {
> > + ERROR("lxcpath too long to monitor fifo");
> > + return -1;
> > + }
> > + unlink(fifo_path);
> > + return 0;
> > +}
> > +
> > +static void lxc_monitord_sockfd_remove(struct lxc_monitor *mon,
> > int fd) {
> > + int i;
> > +
> > + lxc_mainloop_del_handler(&mon->descr, fd);
> > + close(fd);
> > +
> > + for (i = 0; i < mon->clientfds_cnt; i++) {
> > + if (mon->clientfds[i] == fd)
> > + break;
> > + }
> > + if (i >= mon->clientfds_cnt) {
> > + CRIT("fd not found");
> > + exit(EXIT_FAILURE);
> > + }
> > + DEBUG("MON: removing client fd:%d memmoving %p %p %lu
> > bytes", fd,
> > + &mon->clientfds[mon->clientfds_cnt],
> > + &mon->clientfds[i],
> > + (&mon->clientfds[mon->clientfds_cnt-1] -
> > &mon->clientfds[i]) * sizeof(int));
> > + memmove(&mon->clientfds[i], &mon->clientfds[i+1],
> > + (&mon->clientfds[mon->clientfds_cnt-1] -
> > &mon->clientfds[i]) * sizeof(int));
> > + mon->clientfds_cnt--;
> > +}
> > +
> > +static int lxc_monitord_sock_handler(int fd, void *data,
> > + struct lxc_epoll_descr *descr)
> > +{
> > + struct lxc_monitor *mon = data;
> > + lxc_monitord_sockfd_remove(mon, fd);
> > + return 0;
> > +}
> > +
> > +static int lxc_monitord_sock_accept(int fd, void *data,
> > + struct lxc_epoll_descr *descr)
> > +{
> > + int ret,clientfd;
> > + struct lxc_monitor *mon = data;
> > +
> > + ret = -1;
> > + clientfd = accept(fd, NULL, 0);
> > + if (clientfd < 0) {
> > + SYSERROR("failed to accept connection");
> > + goto out;
> > + }
> > +
> > + if (fcntl(clientfd, F_SETFD, FD_CLOEXEC)) {
> > + SYSERROR("failed to set close-on-exec on incoming
> > connection");
> > + goto err1;
> > + }
> > +
> > + /* FIXME: check the connected clients credentials here,
> > drop if we don't
> > + * like them.
> > + int on = 1;
> > + if (setsockopt(clientfd, SOL_SOCKET, SO_PASSCRED, &on,
> > sizeof(on))) {
> > + ERROR("failed to enable credential on socket");
> > + goto err1;
> > + }
> > + */
> > +
> > + ret = lxc_mainloop_add_handler(&mon->descr, clientfd,
> > + lxc_monitord_sock_handler,
> > mon);
> > + if (ret) {
> > + ERROR("failed to add socket handler");
> > + goto err1;
> > + }
> > + mon->clientfds[mon->clientfds_cnt++] = clientfd;
> > + INFO("accepted new client fd:%d clientfds_cnt:%d", clientfd,
> > mon->clientfds_cnt);
> > + goto out;
> > +
> > +err1:
> > + close(clientfd);
> > +out:
> > + return ret;
> > +}
> > +
> > +static int lxc_monitord_sock_create(struct lxc_monitor *mon, const
> > char *lxcpath)
> > +{
> > + struct sockaddr_un addr;
> > + int fd;
> > +
> > + if (lxc_monitor_sock_name(lxcpath, &addr) < 0)
> > + return -1;
> > +
> > + fd = lxc_af_unix_open(addr.sun_path, SOCK_STREAM, O_TRUNC);
> > + if (fd < 0) {
> > + ERROR("failed to open unix socket : %s",
> > strerror(errno));
> > + return -1;
> > + }
> > +
> > + mon->listenfd = fd;
> > + return 0;
> > +}
> > +
> > +static int lxc_monitord_sock_delete(const char *lxcpath)
> > +{
> > + struct sockaddr_un addr;
> > +
> > + if (lxc_monitor_sock_name(lxcpath, &addr) < 0)
> > + return -1;
> > + if (addr.sun_path[0])
> > + unlink(addr.sun_path);
> > + return 0;
> > +}
> > +
> > +static int lxc_monitord_create(struct lxc_monitor *mon, const char
> > *lxcpath)
> > +{
> > + int ret;
> > +
> > + ret = lxc_monitord_fifo_create(mon, lxcpath);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = lxc_monitord_sock_create(mon, lxcpath);
> > + return ret;
> > +}
> > +
> > +static void lxc_monitord_delete(struct lxc_monitor *mon, const char
> > *lxcpath)
> > +{
> > + int i;
> > +
> > + lxc_mainloop_del_handler(&mon->descr, mon->listenfd);
> > + close(mon->listenfd);
> > + lxc_monitord_sock_delete(lxcpath);
> > +
> > + lxc_mainloop_del_handler(&mon->descr, mon->fifofd);
> > + close(mon->fifofd);
> > + lxc_monitord_fifo_delete(lxcpath);
> > +
> > + for (i = 0; i < mon->clientfds_cnt; i++) {
> > + lxc_mainloop_del_handler(&mon->descr,
> > mon->clientfds[i]);
> > + close(mon->clientfds[i]);
> > + }
> > + mon->clientfds_cnt = 0;
> > +}
> > +
> > +static int lxc_monitord_fifo_handler(int fd, void *data,
> > + struct lxc_epoll_descr *descr)
> > +{
> > + int ret,i;
> > + struct lxc_msg msglxc;
> > + struct lxc_monitor *mon = data;
> > +
> > + ret = read(fd, &msglxc, sizeof(msglxc));
> > + if (ret != sizeof(msglxc)) {
> > + SYSERROR("read fifo failed : %s", strerror(errno));
> > + return 1;
> > + }
> > +
> > + for (i = 0; i < mon->clientfds_cnt; i++) {
> > + ret = write(mon->clientfds[i], &msglxc,
> > sizeof(msglxc));
> > + if (ret < 0) {
> > + ERROR("write failed to client sock,
> > removing");
> > + lxc_monitord_sockfd_remove(mon, i);
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int lxc_monitord_mainloop_add(struct lxc_monitor *mon)
> > +{
> > + int ret;
> > +
> > + ret = lxc_mainloop_add_handler(&mon->descr, mon->fifofd,
> > + lxc_monitord_fifo_handler,
> > mon);
> > + if (ret < 0) {
> > + ERROR("failed to add to mainloop monitor handler for
> > fifo");
> > + return -1;
> > + }
> > +
> > + ret = lxc_mainloop_add_handler(&mon->descr, mon->listenfd,
> > + lxc_monitord_sock_accept,
> > mon);
> > + if (ret < 0) {
> > + ERROR("failed to add to mainloop monitor handler for
> > listen socket");
> > + return -1;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static void lxc_monitord_sig_handler(int sig)
> > +{
> > + INFO("caught signal %d", sig);
> > +}
> > +
> > +int main(int argc, char *argv[])
> > +{
> > + struct lxc_monitor mon;
> > + int ret,pipefd;
> > + char *lxcpath = argv[1];
> > + char logpath[PATH_MAX];
> > +
> > + signal(SIGTERM, lxc_monitord_sig_handler);
> > + snprintf(logpath, sizeof(logpath), "%s/lxc-monitord.log",
> > lxcpath);
> > + ret = lxc_log_init(NULL, logpath, "INFO", "lxc-monitord",
> > 0);
> > + if (ret)
> > + return ret;
> > +
> > + pipefd = atoi(argv[2]);
> > +
> > + ret = EXIT_FAILURE;
> > + memset(&mon, 0, sizeof(mon));
> > + if (lxc_mainloop_open(&mon.descr)) {
> > + ERROR("failed to create mainloop");
> > + goto out;
> > + }
> > +
> > + if (lxc_monitord_create(&mon, lxcpath)) {
> > + goto out;
> > + }
> > +
> > + /* sync with parent */
> > + write(pipefd, "S", 1);
> > + close(pipefd);
> > +
> > + if (lxc_monitord_mainloop_add(&mon)) {
> > + ERROR("failed to add mainloop handlers");
> > + goto out;
> > + }
> > +
> > + NOTICE("monitoring lxcpath %s", lxcpath);
> > + for(;;) {
> > + ret = lxc_mainloop_timeout(&mon.descr, 1000 * 30);
> > + if (mon.clientfds_cnt <= 0)
> > + {
> > + NOTICE("no clients for 30 seconds,
> > exiting");
> > + break;
> > + }
> > + }
> > +
> > + lxc_monitord_delete(&mon, lxcpath);
> > + lxc_mainloop_close(&mon.descr);
> > +out:
> > + return ret;
> > +}
> > diff --git a/src/lxc/mainloop.c b/src/lxc/mainloop.c
> > index 975215d..4805dcd 100644
> > --- a/src/lxc/mainloop.c
> > +++ b/src/lxc/mainloop.c
> > @@ -38,7 +38,7 @@ struct mainloop_handler {
> >
> > #define MAX_EVENTS 10
> >
> > -int lxc_mainloop(struct lxc_epoll_descr *descr)
> > +int lxc_mainloop_timeout(struct lxc_epoll_descr *descr, int
> > timeout_ms) {
> > int i, nfds;
> > struct mainloop_handler *handler;
> > @@ -46,7 +46,7 @@ int lxc_mainloop(struct lxc_epoll_descr *descr)
> >
> > for (;;) {
> >
> > - nfds = epoll_wait(descr->epfd, events, MAX_EVENTS,
> > -1);
> > + nfds = epoll_wait(descr->epfd, events, MAX_EVENTS,
> > timeout_ms);
> > if (nfds < 0) {
> > if (errno == EINTR)
> > continue;
> > @@ -64,11 +64,18 @@ int lxc_mainloop(struct lxc_epoll_descr *descr)
> > return 0;
> > }
> >
> > + if (nfds == 0 && timeout_ms != 0)
> > + return 0;
> > +
> > if (lxc_list_empty(&descr->handlers))
> > return 0;
> > }
> > }
> >
> > +int lxc_mainloop(struct lxc_epoll_descr *descr) {
> > + return lxc_mainloop_timeout(descr, -1);
> > +}
> > +
> > int lxc_mainloop_add_handler(struct lxc_epoll_descr *descr, int fd,
> > lxc_mainloop_callback_t callback, void
> > *data) {
> > diff --git a/src/lxc/mainloop.h b/src/lxc/mainloop.h
> > index 6b16242..c79c4fd 100644
> > --- a/src/lxc/mainloop.h
> > +++ b/src/lxc/mainloop.h
> > @@ -21,6 +21,9 @@
> > * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
> > 02111-1307 USA */
> >
> > +#ifndef _mainloop_h
> > +#define _mainloop_h
> > +
> > #include "list.h"
> >
> > struct lxc_epoll_descr {
> > @@ -33,6 +36,8 @@ typedef int (*lxc_mainloop_callback_t)(int fd,
> > void *data,
> >
> > extern int lxc_mainloop(struct lxc_epoll_descr *descr);
> >
> > +extern int lxc_mainloop_timeout(struct lxc_epoll_descr *descr, int
> > timeout_ms);
> > +
> > extern int lxc_mainloop_add_handler(struct lxc_epoll_descr *descr,
> > int fd, lxc_mainloop_callback_t callback,
> > void *data);
> > @@ -42,3 +47,5 @@ extern int lxc_mainloop_del_handler(struct
> > lxc_epoll_descr *descr, int fd);
> > extern int lxc_mainloop_open(struct lxc_epoll_descr *descr);
> >
> > extern int lxc_mainloop_close(struct lxc_epoll_descr *descr);
> > +
> > +#endif
> > diff --git a/src/lxc/monitor.c b/src/lxc/monitor.c
> > index afdaf67..0438fbc 100644
> > --- a/src/lxc/monitor.c
> > +++ b/src/lxc/monitor.c
> > @@ -20,6 +20,7 @@
> > * License along with this library; if not, write to the Free
> > Software
> > * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
> > 02111-1307 USA */
> > +
> > #include <stdio.h>
> > #include <errno.h>
> > #include <unistd.h>
> > @@ -30,7 +31,7 @@
> > #include <sys/stat.h>
> > #include <sys/param.h>
> > #include <sys/socket.h>
> > -#include <sys/un.h>
> > +#include <sys/wait.h>
> > #include <netinet/in.h>
> > #include <net/if.h>
> >
> > @@ -43,35 +44,24 @@
> >
> > lxc_log_define(lxc_monitor, lxc);
> >
> > -#ifndef UNIX_PATH_MAX
> > -#define UNIX_PATH_MAX 108
> > -#endif
> > -
> > -static void lxc_monitor_send(struct lxc_msg *msg, const char
> > *lxcpath) +/* routines used by monitor publishers (containers) */
> > +static void lxc_monitor_fifo_send(struct lxc_msg *msg, const char
> > *lxcpath)
> > {
> > - int fd;
> > - struct sockaddr_un addr = { .sun_family = AF_UNIX };
> > - char *offset = &addr.sun_path[1];
> > - size_t ret, len;
> > + int fd,ret;
> > + char fifo_path[PATH_MAX];
> >
> > - /*
> > - * addr.sun_path is only 108 bytes.
> > - * should we take a hash of lxcpath? a subset of it?
> > - */
> > - len = sizeof(addr.sun_path) - 1;
> > - ret = snprintf(offset, len, "%s/lxc-monitor", lxcpath);
> > - if (ret < 0 || ret >= len) {
> > - ERROR("lxcpath too long to open monitor");
> > + //FIXME: BuildAssert(sizeof(*msg) < PIPE_BUF), "write not
> > guaranteed atomic");
> > + ret = snprintf(fifo_path, sizeof(fifo_path), "%s/monitor",
> > lxcpath);
> > + if (ret < 0 || ret >= sizeof(fifo_path)) {
> > + ERROR("lxcpath too long to open monitor fifo");
> > return;
> > }
> > -
> > - fd = socket(PF_UNIX, SOCK_DGRAM, 0);
> > - if (fd < 0)
> > + fd = open(fifo_path, O_WRONLY);
> > + if (fd < 0) {
> > + ERROR("failed to open monitor fifo %s", fifo_path);
> > return;
> > -
> > - sendto(fd, msg, sizeof(*msg), 0,
> > - (const struct sockaddr *)&addr, sizeof(addr));
> > -
> > + }
> > + ret = write(fd, msg, sizeof(*msg));
> > close(fd);
> > }
> >
> > @@ -82,72 +72,74 @@ void lxc_monitor_send_state(const char *name,
> > lxc_state_t state, const char *lxc
> > strncpy(msg.name, name, sizeof(msg.name));
> > msg.name[sizeof(msg.name) - 1] = 0;
> >
> > - lxc_monitor_send(&msg, lxcpath);
> > + lxc_monitor_fifo_send(&msg, lxcpath);
> > }
> >
> > -int lxc_monitor_open(const char *lxcpath)
> > +
> > +/* routines used by monitor subscribers (lxc-monitor) */
> > +int lxc_monitor_close(int fd)
> > {
> > - struct sockaddr_un addr = { .sun_family = AF_UNIX };
> > - char *offset = &addr.sun_path[1];
> > - int fd;
> > - size_t ret, len;
> > + return close(fd);
> > +}
> >
> > - /*
> > - * addr.sun_path is only 108 bytes.
> > - * should we take a hash of lxcpath? a subset of it?
> > +int lxc_monitor_sock_name(const char *lxcpath, struct sockaddr_un
> > *addr) {
> > + size_t len,ret;
> > + char *sockname = &addr->sun_path[0]; // 1 for abstract
> > +
> > + /* addr.sun_path is only 108 bytes.
> > + * should we take a hash of lxcpath? a subset of it?
> > ftok()? none
> > + * are guaranteed.
> > */
> > - len = sizeof(addr.sun_path) - 1;
> > - ret = snprintf(offset, len, "%s/lxc-monitor", lxcpath);
> > + memset(addr, 0, sizeof(*addr));
> > + addr->sun_family = AF_UNIX;
> > + len = sizeof(addr->sun_path) - 1;
> > + ret = snprintf(sockname, len, "%s/monitor-sock", lxcpath);
> > if (ret < 0 || ret >= len) {
> > - ERROR("lxcpath too long to open monitor");
> > + ERROR("lxcpath too long for unix socket");
> > return -1;
> > }
> > + return 0;
> > +}
> > +
> > +int lxc_monitor_open(const char *lxcpath)
> > +{
> > + struct sockaddr_un addr;
> > + size_t ret;
> > + int fd;
> >
> > - fd = socket(PF_UNIX, SOCK_DGRAM, 0);
> > + if (lxc_monitor_sock_name(lxcpath, &addr) < 0)
> > + return -1;
> > +
> > + fd = socket(PF_UNIX, SOCK_STREAM, 0);
> > if (fd < 0) {
> > ERROR("socket : %s", strerror(errno));
> > return -1;
> > }
> >
> > - if (bind(fd, (struct sockaddr *)&addr, sizeof(addr))) {
> > - ERROR("bind : %s", strerror(errno));
> > - close(fd);
> > - return -1;
> > + ret = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
> > + if (ret < 0) {
> > + /* try to spawn a lxc-monitord here instead ? */
> > + ERROR("connect : %s", strerror(errno));
> > + goto err1;
> > }
> > -
> > return fd;
> > +err1:
> > + close(fd);
> > + return ret;
> > }
> >
> > -/* timeout of 0 means return immediately; -1 means wait forever */
> > -int lxc_monitor_read_timeout(int fd, struct lxc_msg *msg, int
> > timeout) +int lxc_monitor_read_timeout(int fd, struct lxc_msg
> > *msglxc, int timeout) {
> > struct sockaddr_un from;
> > socklen_t len = sizeof(from);
> > int ret;
> > - fd_set rfds;
> > - struct timeval tv;
> >
> > - if (timeout != -1) {
> > - FD_ZERO(&rfds);
> > - FD_SET(fd, &rfds);
> > -
> > - tv.tv_sec = timeout;
> > - tv.tv_usec = 0;
> > -
> > - ret = select(fd+1, &rfds, NULL, NULL, &tv);
> > - if (ret == -1)
> > - return -1;
> > - else if (!ret)
> > - return -2; // timed out
> > - }
> > -
> > - ret = recvfrom(fd, msg, sizeof(*msg), 0,
> > + ret = recvfrom(fd, msglxc, sizeof(*msglxc), 0,
> > (struct sockaddr *)&from, &len);
> > - if (ret < 0) {
> > - SYSERROR("failed to receive state");
> > + if (ret <= 0) {
> > + SYSERROR("client failed to receive lxc_msg (monitord
> > died?)");
> > return -1;
> > }
> > -
> > return ret;
> > }
> >
> > @@ -156,7 +148,61 @@ int lxc_monitor_read(int fd, struct lxc_msg
> > *msg) return lxc_monitor_read_timeout(fd, msg, -1);
> > }
> >
> > -int lxc_monitor_close(int fd)
> > +
> > +
> > +/* used to spawn a monitord either on startup of a container, or
> > when
> > + * lxc-monitor starts
> > + */
> > +int lxc_monitord_spawn(const char *lxcpath)
> > {
> > - return close(fd);
> > + pid_t pid1,pid2;
> > + int pipefd[2];
> > + char pipefd_str[10];
> > +
> > + char * const args[] = {
> > + "/usr/bin/lxc-monitord",
> > + (char *)lxcpath,
> > + pipefd_str,
> > + NULL,
> > + };
> > +
> > + /* double fork to avoid zombies when monitord exits */
> > + pid1 = fork();
> > + if (pid1 < 0) {
> > + SYSERROR("failed to fork");
> > + return -1;
> > + }
> > +
> > + if (pid1) {
> > + waitpid(pid1, NULL, 0);
> > + return 0;
> > + }
> > +
> > + if (pipe(pipefd) < 0) {
> > + SYSERROR("failed to create pipe");
> > + exit(EXIT_FAILURE);
> > + }
> > +
> > + pid2 = fork();
> > + if (pid2) {
> > + char c;
> > + /* wait for daemon to create socket */
> > + close(pipefd[1]);
> > + read(pipefd[0], &c, 1);
> > + close(pipefd[0]);
> > + exit(EXIT_SUCCESS);
> > + }
> > +
> > + umask(0);
> > + if (setsid() < 0) {
> > + SYSERROR("failed to setsid");
> > + exit(EXIT_FAILURE);
> > + }
> > + freopen("/dev/null", "r", stdin);
> > + freopen("/dev/null", "w", stdout);
> > + freopen("/dev/null", "w", stderr);
> > + close(pipefd[0]);
> > + sprintf(pipefd_str, "%d", pipefd[1]);
> > + execvp(args[0], args);
> > + exit(EXIT_FAILURE);
> > }
> > diff --git a/src/lxc/monitor.h b/src/lxc/monitor.h
> > index 8bef4c7..faa606c 100644
> > --- a/src/lxc/monitor.h
> > +++ b/src/lxc/monitor.h
> > @@ -24,6 +24,10 @@
> > #define __monitor_h
> >
> > #include <sys/param.h>
> > +#include <sys/un.h>
> > +
> > +#include <lxc/conf.h>
> > +#include <lxc/mainloop.h>
> >
> > typedef enum {
> > lxc_msg_state,
> > @@ -32,11 +36,14 @@ typedef enum {
> >
> > struct lxc_msg {
> > lxc_msg_type_t type;
> > - char name[MAXPATHLEN];
> > + char name[NAME_MAX+1];
> > int value;
> > };
> >
> > -void lxc_monitor_send_state(const char *name, lxc_state_t state,
> > +extern int lxc_monitor_open(const char *lxcpath);
> > +extern int lxc_monitor_sock_name(const char *lxcpath, struct
> > sockaddr_un *addr);
> > +extern void lxc_monitor_send_state(const char *name, lxc_state_t
> > state, const char *lxcpath);
> > +extern int lxc_monitord_spawn(const char *lxcpath);
> >
> > #endif
> > diff --git a/src/lxc/start.c b/src/lxc/start.c
> > index aefccd6..9451fb7 100644
> > --- a/src/lxc/start.c
> > +++ b/src/lxc/start.c
> > @@ -429,6 +429,9 @@ struct lxc_handler *lxc_init(const char *name,
> > struct lxc_conf *conf, const char
> > if (lxc_command_init(name, handler, lxcpath))
> > goto out_free_name;
> >
> > + if (lxc_monitord_spawn(lxcpath))
> > + goto out_close_maincmd_fd;
> > +
> > if (lxc_read_seccomp_config(conf) != 0) {
> > ERROR("failed loading seccomp policy");
> > goto out_close_maincmd_fd;
> > @@ -437,7 +440,7 @@ struct lxc_handler *lxc_init(const char *name,
> > struct lxc_conf *conf, const char
> > /* Begin the set the state to STARTING*/
> > if (lxc_set_state(name, handler, STARTING)) {
> > ERROR("failed to set state '%s'",
> > lxc_state2str(STARTING));
> > - goto out_free_name;
> > + goto out_close_maincmd_fd;
> > }
> >
> > /* Start of environment variable setup for hooks */
> > @@ -808,7 +811,7 @@ int lxc_spawn(struct lxc_handler *handler)
> > /* TODO - pass lxc.cgroup.dir (or user's pam cgroup) in for
> > first argument */
> > if ((handler->cgroup = lxc_cgroup_path_create(NULL, name))
> > == NULL) goto out_delete_net;
> > -
> > +
> > if (lxc_cgroup_enter(handler->cgroup, handler->pid) < 0)
> > goto out_delete_net;
> >
> > --
> > 1.8.1.4
> >
> >
> >
> >
> > ------------------------------------------------------------------------------
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> > analytics on semi-structured data. The platform includes APIs for
> > building apps and a phenomenal toolset for data science. Developers
> > can use our toolset for easy data analysis & visualization. Get a
> > free account!
> > http://www2.precog.com/precogplatform/slashdotnewsletter
> > _______________________________________________ Lxc-devel mailing
> > list Lxc-devel at lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/lxc-devel
> >
>
>
>
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