log: enable per-thread container name prefix

When using the LXC API multi-thread and users initialize a log:

struct lxc_log log;
log.name = "my-log";
lxc_log_init(&log);

all threads will have the same "my-log" prefix even though thy might call
lxc_container_new() in separate threads. There is currently no easy way to
handle per-thread container name prefixes.
To handle this carry a reference to the name of the container in struct
lxc_conf and if no log.name was set, use it by default. This way each thread
will get the container it is currently working on as a log-prefix.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reported-by: duguhaotian <duguhaotian@gmail.com>

diff --git a/src/lxc/conf.h b/src/lxc/conf.h
index 351059c9432c0a7d71177038c23fc93e2aabc966..d77a484151437623cc7a6dc43be9b5cbb3190000 100644 (file)
--- a/src/lxc/conf.h
+++ b/src/lxc/conf.h
@@ -228,6 +228,8 @@ struct lxc_state_client {
 };
 
 struct lxc_conf {
+       /* Pointer to the name of the container. Do not free! */
+       const char *name;
        int is_execute;
        char *fstab;
        unsigned int tty;

diff --git a/src/lxc/log.c b/src/lxc/log.c
index 94b61d4324c2bc26cad072b43e213c69c5e6fa57..46e54a88ddadf18b247a221b4efcfdd1d8ae28eb 100644 (file)
--- a/src/lxc/log.c
+++ b/src/lxc/log.c
@@ -102,6 +102,12 @@ static int log_append_syslog(const struct lxc_log_appender *appender,
        char *msg;
        int rc, len;
        va_list args;
+       const char *log_container_name = log_vmname;
+
+#ifndef NO_LXC_CONF
+       if (current_config && !log_container_name)
+               log_container_name = current_config->name;
+#endif
 
        if (!syslog_enable)
                return 0;
@@ -109,9 +115,11 @@ static int log_append_syslog(const struct lxc_log_appender *appender,
        va_copy(args, *event->vap);
        len = vsnprintf(NULL, 0, event->fmt, args) + 1;
        va_end(args);
+
        msg = malloc(len * sizeof(char));
        if (msg == NULL)
                return 0;
+
        rc = vsnprintf(msg, len, event->fmt, *event->vap);
        if (rc == -1 || rc >= len) {
                free(msg);
@@ -120,13 +128,14 @@ static int log_append_syslog(const struct lxc_log_appender *appender,
 
        syslog(lxc_log_priority_to_syslog(event->priority),
                "%s%s %s - %s:%s:%d - %s" ,
-               log_vmname ? log_vmname : "",
-               log_vmname ? ":" : "",
+               log_container_name ? log_container_name : "",
+               log_container_name ? ":" : "",
                event->category,
                event->locinfo->file, event->locinfo->func,
                event->locinfo->line,
                msg);
        free(msg);
+
        return 0;
 }
 
@@ -134,13 +143,26 @@ static int log_append_syslog(const struct lxc_log_appender *appender,
 static int log_append_stderr(const struct lxc_log_appender *appender,
                             struct lxc_log_event *event)
 {
+       const char *log_container_name;
+
        if (event->priority < LXC_LOG_LEVEL_ERROR)
                return 0;
 
-       fprintf(stderr, "%s: %s%s", log_prefix, log_vmname ? log_vmname : "", log_vmname ? ": " : "");
-       fprintf(stderr, "%s: %s: %d ", event->locinfo->file, event->locinfo->func, event->locinfo->line);
+       log_container_name = log_vmname;
+
+#ifndef NO_LXC_CONF
+       if (current_config && !log_container_name)
+               log_container_name = current_config->name;
+#endif
+
+       fprintf(stderr, "%s: %s%s", log_prefix,
+               log_container_name ? log_container_name : "",
+               log_container_name ? ": " : "");
+       fprintf(stderr, "%s: %s: %d ", event->locinfo->file,
+               event->locinfo->func, event->locinfo->line);
        vfprintf(stderr, event->fmt, *event->vap);
        fprintf(stderr, "\n");
+
        return 0;
 }
 
@@ -270,10 +292,16 @@ static int log_append_logfile(const struct lxc_log_appender *appender,
        char date_time[LXC_LOG_TIME_SIZE];
        int n, ret;
        int fd_to_use = -1;
+       const char *log_container_name = log_vmname;
 
 #ifndef NO_LXC_CONF
-       if (!lxc_log_use_global_fd && current_config)
-               fd_to_use = current_config->logfd;
+       if (current_config) {
+               if (!lxc_log_use_global_fd)
+                       fd_to_use = current_config->logfd;
+
+               if (!log_container_name)
+                       log_container_name = current_config->name;
+       }
 #endif
 
        if (fd_to_use == -1)
@@ -288,8 +316,8 @@ static int log_append_logfile(const struct lxc_log_appender *appender,
        n = snprintf(buffer, sizeof(buffer),
                        "%s%s%s %s %-8s %s - %s:%s:%d - ",
                        log_prefix,
-                       log_vmname ? " " : "",
-                       log_vmname ? log_vmname : "",
+                       log_container_name ? " " : "",
+                       log_container_name ? log_container_name : "",
                        date_time,
                        lxc_log_priority_to_string(event->priority),
                        event->category,

diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
index a9041c860140ff77b205266f8dada046da41a667..3588d79a1beda53a47d693153decb6b6d2981be4 100644 (file)
--- a/src/lxc/lxccontainer.c
+++ b/src/lxc/lxccontainer.c
@@ -595,6 +595,8 @@ static bool load_config_locked(struct lxc_container *c, const char *fname)
        if (lxc_config_read(fname, c->lxc_conf, false) != 0)
                return false;
 
+       c->lxc_conf->name = c->name;
+
        return true;
 }