confile: add lxc.monitor.signal.pdeath

doc/lxc.container.conf.sgml.in

@@ -2380,6 +2380,21 @@ dev/null proc/kcore none bind,relative 0 0
         </varlistentry>
         <varlistentry>
           <term>
+            <option>lxc.monitor.signal.pdeath</option>
+          </term>
+          <listitem>
+            <para>
+              Set the signal to be sent to the container's init when the lxc
+              monitor exits. By default it is set to SIGKILL which will cause
+              all container processes to be killed when the lxc monitor process
+              dies.
+              To ensure that containers stay alive even if lxc monitor dies set
+              this to 0.
+            </para>
+          </listitem>
+        </varlistentry>
+        <varlistentry>
+          <term>
             <option>lxc.group</option>
           </term>
           <listitem>

src/lxc/conf.c

@@ -2673,6 +2673,7 @@ struct lxc_conf *lxc_conf_init(void)
 	new->console.name[0] = '\0';
 	memset(&new->console.ringbuf, 0, sizeof(struct lxc_ringbuf));
 	new->maincmd_fd = -1;
+	new->monitor_signal_pdeath = SIGKILL;
 	new->nbd_idx = -1;
 	new->rootfs.mount = strdup(default_rootfs_mount);
 	if (!new->rootfs.mount) {

src/lxc/conf.h

@@ -303,6 +303,7 @@ struct lxc_conf {
 
 	/* unshare the mount namespace in the monitor */
 	unsigned int monitor_unshare;
+	unsigned int monitor_signal_pdeath;
 
 	/* list of included files */
 	struct lxc_list includes;

src/lxc/confile.c

@@ -111,6 +111,7 @@ lxc_config_define(log_file);
 lxc_config_define(log_level);
 lxc_config_define(log_syslog);
 lxc_config_define(monitor);
+lxc_config_define(monitor_signal_pdeath);
 lxc_config_define(mount);
 lxc_config_define(mount_auto);
 lxc_config_define(mount_fstab);
@@ -194,6 +195,7 @@ static struct lxc_config_t config[] = {
 	{ "lxc.log.level",                 set_config_log_level,                   get_config_log_level,                   clr_config_log_level,                 },
 	{ "lxc.log.syslog",                set_config_log_syslog,                  get_config_log_syslog,                  clr_config_log_syslog,                },
 	{ "lxc.monitor.unshare",           set_config_monitor,                     get_config_monitor,                     clr_config_monitor,                   },
+	{ "lxc.monitor.signal.pdeath",     set_config_monitor_signal_pdeath,       get_config_monitor_signal_pdeath,       clr_config_monitor_signal_pdeath,     },
 	{ "lxc.mount.auto",                set_config_mount_auto,                  get_config_mount_auto,                  clr_config_mount_auto,                },
 	{ "lxc.mount.entry",               set_config_mount,                       get_config_mount,                       clr_config_mount,                     },
 	{ "lxc.mount.fstab",               set_config_mount_fstab,                 get_config_mount_fstab,                 clr_config_mount_fstab,               },
@@ -976,6 +978,28 @@ static int set_config_monitor(const char *key, const char *value,
 	return -1;
 }
 
+static int set_config_monitor_signal_pdeath(const char *key, const char *value,
+					    struct lxc_conf *lxc_conf, void *data)
+{
+	if (lxc_config_value_empty(value)) {
+		lxc_conf->monitor_signal_pdeath = 0;
+		return 0;
+	}
+
+	if (strcmp(key + 12, "signal.pdeath") == 0) {
+		int sig_n;
+
+		sig_n = sig_parse(value);
+		if (sig_n < 0)
+			return -1;
+
+		lxc_conf->monitor_signal_pdeath = sig_n;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
 static int set_config_group(const char *key, const char *value,
 			    struct lxc_conf *lxc_conf, void *data)
 {
@@ -3420,6 +3444,13 @@ static int get_config_monitor(const char *key, char *retv, int inlen,
 	return lxc_get_conf_int(c, retv, inlen, c->monitor_unshare);
 }
 
+static int get_config_monitor_signal_pdeath(const char *key, char *retv,
+					    int inlen, struct lxc_conf *c,
+					    void *data)
+{
+	return lxc_get_conf_int(c, retv, inlen, c->monitor_signal_pdeath);
+}
+
 static int get_config_group(const char *key, char *retv, int inlen,
 			    struct lxc_conf *c, void *data)
 {
@@ -3971,6 +4002,13 @@ static inline int clr_config_monitor(const char *key, struct lxc_conf *c,
 	return 0;
 }
 
+static inline int clr_config_monitor_signal_pdeath(const char *key,
+						   struct lxc_conf *c, void *data)
+{
+	c->monitor_signal_pdeath = 0;
+	return 0;
+}
+
 static inline int clr_config_group(const char *key, struct lxc_conf *c,
 				   void *data)
 {

src/lxc/start.c

@@ -1370,6 +1370,15 @@ static int do_start(void *data)
 		goto out_warn_father;
 	}
 
+	if (handler->conf->monitor_signal_pdeath != SIGKILL) {
+		ret = lxc_set_death_signal(handler->conf->monitor_signal_pdeath);
+		if (ret < 0) {
+			SYSERROR("Failed to set PR_SET_PDEATHSIG to %d",
+				 handler->conf->monitor_signal_pdeath);
+			goto out_warn_father;
+		}
+	}
+
 	/* After this call, we are in error because this ops should not return
 	 * as it execs.
 	 */